.\" $Id: ppp.8,v 1.125 1998/09/17 00:45:12 brian Exp $ .Dd 20 September 1995 .Os FreeBSD .Dt PPP 8 .Sh NAME .Nm ppp .Nd Point to Point Protocol (a.k.a. user-ppp) .Sh SYNOPSIS .Nm .Oo .Fl auto | .Fl background | .Fl ddial | .Fl direct | .Fl dedicated .Oc .Op Fl alias .Op Ar system .Sh DESCRIPTION This is a user process .Em PPP software package. Normally, .Em PPP is implemented as a part of the kernel (e.g. as managed by .Xr pppd 8 ) and it's thus somewhat hard to debug and/or modify its behaviour. However, in this implementation .Em PPP is done as a user process with the help of the tunnel device driver (tun). .Sh Major Features .Bl -diag .It Provides interactive user interface. Using its command mode, the user can easily enter commands to establish the connection with the remote end, check the status of connection and close the connection. All functions can also be optionally password protected for security. .It Supports both manual and automatic dialing. Interactive mode has a .Dq term command which enables you to talk to your modem directly. When your modem is connected to the remote peer and it starts to talk .Em PPP , .Nm detects it and switches to packet mode automatically. Once you have determined the proper sequence for connecting with the remote host, you can write a chat script to define the necessary dialing and login procedure for later convenience. .It Supports on-demand dialup capability. By using .Fl auto mode, .Nm will act as a daemon and wait for a packet to be sent over the .Em PPP link. When this happens, the daemon automatically dials and establishes the connection. In almost the same manner .Fl ddial mode (direct-dial mode) also automatically dials and establishes the connection. However, it differs in that it will dial the remote site any time it detects the link is down, even if there are no packets to be sent. This mode is useful for full-time connections where we worry less about line charges and more about being connected full time. A third .Fl dedicated mode is also available. This mode is targeted at a dedicated link between two machines. .Nm Ppp will never voluntarily quit from dedicated mode - you must send it the .Dq quit all command via its diagnostic socket. A .Dv SIGHUP will force an LCP renegotiation, and a .Dv SIGTERM will force it to exit. .It Supports client callback. .Nm Ppp can use either the standard LCP callback protocol or the Microsoft CallBack Control Protocol (ftp://ftp.microsoft.com/developr/rfc/cbcp.txt). .It Supports packet aliasing. Packet aliasing (a.k.a. IP masquerading) allows computers on a private, unregistered network to access the Internet. The .Em PPP host acts as a masquerading gateway. IP addresses as well as TCP and UDP port numbers are aliased for outgoing packets and de-aliased for returning packets. .It Supports background PPP connections. In background mode, if .Nm successfully establishes the connection, it will become a daemon. Otherwise, it will exit with an error. This allows the setup of scripts that wish to execute certain commands only if the connection is successfully established. .It Supports server-side PPP connections. In direct mode, .nm acts as server which accepts incoming .Em PPP connections on stdin/stdout. .It Supports PAP and CHAP authentication. With PAP or CHAP, it is possible to skip the Unix style .Xr login 1 procedure, and use the .Em PPP protocol for authentication instead. If the peer requests Microsoft CHAP authentication and .Nm is compiled with DES support, an appropriate MD4/DES response will be made. .It Supports Proxy Arp. When .Em PPP is set up as server, you can also configure it to do proxy arp for your connection. .It Supports packet filtering. User can define four kinds of filters: the .Em in filter for incoming packets, the .Em out filter for outgoing packets, the .Em dial filter to define a dialing trigger packet and the .Em alive filter for keeping a connection alive with the trigger packet. .It Tunnel driver supports bpf. The user can use .Xr tcpdump 1 to check the packet flow over the .Em PPP link. .It Supports PPP over TCP capability. If a device name is specified as .Em host Ns No : Ns Em port , .Nm will open a TCP connection for transporting data rather than using a conventional serial device. .It Supports IETF draft Predictor-1 and DEFLATE compression. .Nm supports not only VJ-compression but also Predictor-1 and DEFLATE compression. Normally, a modem has built-in compression (e.g. v42.bis) and the system may receive higher data rates from it as a result of such compression. While this is generally a good thing in most other situations, this higher speed data imposes a penalty on the system by increasing the number of serial interrupts the system has to process in talking to the modem and also increases latency. Unlike VJ-compression, Predictor-1 and DEFLATE compression pre-compresses .Em all network traffic flowing through the link, thus reducing overheads to a minimum. .It Supports Microsoft's IPCP extensions. Name Server Addresses and NetBIOS Name Server Addresses can be negotiated with clients using the Microsoft .Em PPP stack (ie. Win95, WinNT) .It Supports Multi-link PPP It is possible to configure .Nm to open more than one physical connection to the peer, combining the bandwidth of all links for better throughput. .El .Sh PERMISSIONS .Nm Ppp is installed as user .Dv root and group .Dv network , with permissions .Dv 4554 . By default, .Nm will not run if the invoking user id is not zero. This may be overridden by using the .Dq allow users command in .Pa /etc/ppp/ppp.conf . When running as a normal user, .Nm switches to user id 0 in order to alter the system routing table, set up system lock files and read the ppp configuration files. All external commands (executed via the "shell" or "!bg" commands) are executed as the user id that invoked .Nm ppp . Refer to the .Sq ID0 logging facility if you're interested in what exactly is done as user id zero. .Sh GETTING STARTED When you first run .Nm you may need to deal with some initial configuration details. .Bl -bullet .It Your kernel must include a tunnel device (the GENERIC kernel includes one by default). If it doesn't, or if you require more than one tun interface, you'll need to rebuild your kernel with the following line in your kernel configuration file: .Pp .Dl pseudo-device tun N .Pp where .Ar N is the maximum number of .Em PPP connections you wish to support. .It Check your .Pa /dev directory for the tunnel device entries .Pa /dev/tunN , where .Sq N represents the number of the tun device, starting at zero. If they don't exist, you can create them by running "sh ./MAKEDEV tunN". This will create tun devices 0 through .Ar N . .It Make sure that your system has a group named .Dq network in the .Pa /etc/group file and that that group contains the names of all users expected to use .Nm ppp . Refer to the .Xr group 5 manual page for details. Each of these uses must also be given access using the .Dq allow users command in .Pa /etc/ppp/ppp.conf . .It Create a log file. .Nm Ppp uses .Xr syslog 3 to log information. A common log file name is .Pa /var/log/ppp.log . To make output go to this file, put the following lines in the .Pa /etc/syslog.conf file: .Bd -literal -offset indent !ppp *.*/var/log/ppp.log .Ed .Pp Make sure you use actual TABs here. If you use spaces, the line will be silently ignored by .Xr syslogd 8 . .Pp It is possible to have more than one .Em PPP log file by creating a link to the .Nm executable: .Pp .Dl # cd /usr/sbin .Dl # ln ppp ppp0 .Pp and using .Bd -literal -offset indent !ppp0 *.*/var/log/ppp0.log .Ed .Pp in .Pa /etc/syslog.conf . Don't forget to send a .Dv HUP signal to .Xr syslogd 8 after altering .Pa /etc/syslog.conf . .It Although not strictly relevant to .Nm ppp Ns No s operation, you should configure your resolver so that it works correctly. This can be done by configuring a local DNS .Pq using Xr named 8 or by adding the correct .Sq name-server lines to the file .Pa /etc/resolv.conf . Refer to the .Xr resolv.conf 5 manual page for details. .Pp Alternatively, if the peer supports it, .Nm can be configured to ask the peer for the nameserver address(es) and to update .Pa /etc/resolv.conf automatically. Refer to the .Dq enable dns command below for details. .El .Sh MANUAL DIALING In the following examples, we assume that your machine name is .Dv awfulhak . when you invoke .Nm (see .Em PERMISSIONS above) with no arguments, you are presented with a prompt: .Bd -literal -offset indent ppp ON awfulhak> .Ed .Pp The .Sq ON part of your prompt should always be in upper case. If it is in lower case, it means that you must supply a password using the .Dq passwd command. This only ever happens if you connect to a running version of .Nm and have not authenticated yourself using the correct password. .Pp You can start by specifying the device name, speed and parity for your modem, and whether CTS/RTS signalling should be used (CTS/RTS is used by default). If your hardware does not provide CTS/RTS lines (as may happen when you are connected directly to certain PPP-capable terminal servers), .Nm will never send any output through the port; it waits for a signal which never comes. Thus, if you have a direct line and can't seem to make a connection, try turning CTS/RTS off: .Bd -literal -offset indent ppp ON awfulhak> set line /dev/cuaa0 ppp ON awfulhak> set speed 38400 ppp ON awfulhak> set parity even ppp ON awfulhak> set ctsrts on ppp ON awfulhak> show modem * Modem related information is shown here * ppp ON awfulhak> .Ed .Pp The term command can now be used to talk directly with your modem: .Bd -literal -offset indent ppp ON awfulhak> term at OK atdt123456 CONNECT login: ppp Password: Protocol: ppp .Ed .Pp When the peer starts to talk in .Em PPP , .Nm detects this automatically and returns to command mode. .Bd -literal -offset indent ppp ON awfulhak> Ppp ON awfulhak> PPp ON awfulhak> PPP ON awfulhak> .Ed .Pp If it does not, it's possible that the peer is waiting for your end to start negotiating. To force .Nm to start sending PPP configuration packets to the peer, use the .Dq ~p command to enter packet mode. .Pp You are now connected! Note that .Sq PPP in the prompt has changed to capital letters to indicate that you have a peer connection. If only some of the three Ps go uppercase, wait 'till either everything is uppercase or lowercase. If they revert to lowercase, it means that .Nm couldn't successfully negotiate with the peer. This is probably because your PAP or CHAP authentication name or key is incorrect. A good first step for troubleshooting at this point would be to .Dq set log local phase . Refer to the .Dq set log command description below for further details. .Pp When the link is established, the show command can be used to see how things are going: .Bd -literal -offset indent PPP ON awfulhak> show modem * Modem related information is shown here * PPP ON awfulhak> show ccp * CCP (compression) related information is shown here * PPP ON awfulhak> show lcp * LCP (line control) related information is shown here * PPP ON awfulhak> show ipcp * IPCP (IP) related information is shown here * PPP ON awfulhak> show link * Link (high level) related information is shown here * PPP ON awfulhak> show bundle * Logical (high level) connection related information is shown here * .Ed .Pp At this point, your machine has a host route to the peer. This means that you can only make a connection with the host on the other side of the link. If you want to add a default route entry (telling your machine to send all packets without another routing entry to the other side of the .Em PPP link), enter the following command: .Bd -literal -offset indent PPP ON awfulhak> add default HISADDR .Ed .Pp The string .Sq HISADDR represents the IP address of the connected peer. It is possible to use the keyword .Sq INTERFACE in place of .Sq HISADDR . This will create a direct route on the tun interface. If it fails due to an existing route, you can overwrite the existing route using .Bd -literal -offset indent PPP ON awfulhak> add! default HISADDR .Ed .Pp You can now use your network applications (ping, telnet, ftp etc.) in other windows on your machine. Refer to the .Em PPP COMMAND LIST section for details on all available commands. .Sh AUTOMATIC DIALING To use automatic dialing, you must prepare some Dial and Login chat scripts. See the example definitions in .Pa /etc/ppp/ppp.conf.sample (the format of .Pa /etc/ppp/ppp.conf is pretty simple). Each line contains one comment, inclusion, label or command: .Bl -bullet .It A line starting with a .Pq Dq # character is treated as a comment line. Leading whitespace are ignored when identifying comment lines. .It An inclusion is a line beginning with the word .Sq !include . It must have one argument - the file to include. You may wish to .Dq !include ~/.ppp.conf for compatibility with older versions of .Nm ppp . .It A label name starts in the first column and is followed by a colon .Pq Dq \&: . .It A command line must contain a space or tab in the first column. .El .Pp The .Pa /etc/ppp/ppp.conf file should consist of at least a .Dq default section. This section is always executed. It should also contain one or more sections, named according to their purpose, for example, .Dq MyISP would represent your ISP, and .Dq ppp-in would represent an incoming .Nm configuration. You can now specify the destination label name when you invoke .Nm ppp . Commands associated with the .Dq default label are executed, followed by those associated with the destination label provided. When .Nm is started with no arguments, the .Dq default section is still executed. The load command can be used to manually load a section from the .Pa /etc/ppp/ppp.conf file: .Bd -literal -offset indent PPP ON awfulhak> load MyISP .Ed .Pp Once the connection is made, the .Sq ppp portion of the prompt will change to .Sq PPP : .Bd -literal -offset indent # ppp MyISP ... ppp ON awfulhak> dial Ppp ON awfulhak> PPp ON awfulhak> PPP ON awfulhak> .Ed .Pp The Ppp prompt indicates that .Nm has entered the authentication phase. The PPp prompt indicates that .Nm has entered the network phase. The PPP prompt indicates that .Nm has successfully negotiated a network layer protocol and is in a usable state. .Pp If the .Pa /etc/ppp/ppp.linkup file is available, its contents are executed when the .Em PPP connection is established. See the provided .Dq pmdemand example in .Pa /etc/ppp/ppp.conf.sample which runs a script in the background after the connection is established. The literal strings .Dv HISADDR , .Dv MYADDR and .Dv INTERFACE may be used, and will be replaced with the relevant IP addresses and interface name. Similarly, when a connection is closed, the contents of the .Pa /etc/ppp/ppp.linkdown file are executed. Both of these files have the same format as .Pa /etc/ppp/ppp.conf . .Pp In previous versions of .Nm ppp , it was necessary to re-add routes such as the default route in the .Pa ppp.linkup file. .Nm Ppp now supports .Sq sticky routes , where all routes that contain the .Dv HISADDR or .Dv MYADDR literals will automatically be updated when the values of .Dv HISADDR and/or .Dv MYADDR change. .Sh BACKGROUND DIALING If you want to establish a connection using .Nm non-interactively (such as from a .Xr crontab 5 entry or an .Xr at 1 job) you should use the .Fl background option. When .Fl background is specified, .Nm attempts to establish the connection immediately. If multiple phone numbers are specified, each phone number will be tried once. If the attempt fails, .Nm exits immediately with a non-zero exit code. If it succeeds, then .Nm becomes a daemon, and returns an exit status of zero to its caller. The daemon exits automatically if the connection is dropped by the remote system, or it receives a .Dv TERM signal. .Sh DIAL ON DEMAND Demand dialing is enabled with the .Fl auto or .Fl ddial options. You must also specify the destination label in .Pa /etc/ppp/ppp.conf to use. It must contain the .Dq set ifaddr command to define the remote peers IP address. (refer to .Pa /etc/ppp/ppp.conf.sample ) .Bd -literal -offset indent # ppp -auto pmdemand .Ed .Pp When .Fl auto or .Fl ddial is specified, .Nm runs as a daemon but you can still configure or examine its configuration by using the .Dq set server command in .Pa /etc/ppp/ppp.conf , .Pq for example, Dq set server +3000 mypasswd and connecting to the diagnostic port as follows: .Bd -literal -offset indent # pppctl 3000 (assuming tun0 - see the ``set server'' description) Password: PPP ON awfulhak> show who tcp (127.0.0.1:1028) * .Ed .Pp The .Dq show who command lists users that are currently connected to .Nm itself. If the diagnostic socket is closed or changed to a different socket, all connections are immediately dropped. .Pp In .Fl auto mode, when an outgoing packet is detected, .Nm will perform the dialing action (chat script) and try to connect with the peer. In .Fl ddial mode, the dialing action is performed any time the line is found to be down. If the connect fails, the default behaviour is to wait 30 seconds and then attempt to connect when another outgoing packet is detected. This behaviour can be changed with .Bd -literal -offset indent set redial seconds|random[.nseconds|random] [dial_attempts] .Ed .Pp .Sq Seconds is the number of seconds to wait before attempting to connect again. If the argument is .Sq random , the delay period is a random value between 0 and 30 seconds. .Sq Nseconds is the number of seconds to wait before attempting to dial the next number in a list of numbers (see the .Dq set phone command). The default is 3 seconds. Again, if the argument is .Sq random , the delay period is a random value between 0 and 30 seconds. .Sq dial_attempts is the number of times to try to connect for each outgoing packet that is received. The previous value is unchanged if this parameter is omitted. If a value of zero is specified for .Sq dial_attempts , .Nm will keep trying until a connection is made. .Bd -literal -offset indent set redial 10.3 4 .Ed .Pp will attempt to connect 4 times for each outgoing packet that is detected with a 3 second delay between each number and a 10 second delay after all numbers have been tried. If multiple phone numbers are specified, the total number of attempts is still 4 (it does not attempt each number 4 times). Modifying the dial delay is very useful when running .Nm in demand dial mode on both ends of the link. If each end has the same timeout, both ends wind up calling each other at the same time if the link drops and both ends have packets queued. At some locations, the serial link may not be reliable, and carrier may be lost at inappropriate times. It is possible to have .Nm redial should carrier be unexpectedly lost during a session. .Bd -literal -offset indent set reconnect timeout ntries .Ed .Pp This command tells .Nm to re-establish the connection .Ar ntries times on loss of carrier with a pause of .Ar timeout seconds before each try. For example, .Bd -literal -offset indent set reconnect 3 5 .Ed .Pp tells .Nm that on an unexpected loss of carrier, it should wait .Ar 3 seconds before attempting to reconnect. This may happen up to .Ar 5 times before .Nm gives up. The default value of ntries is zero (no reconnect). Care should be taken with this option. If the local timeout is slightly longer than the remote timeout, the reconnect feature will always be triggered (up to the given number of times) after the remote side times out and hangs up. NOTE: In this context, losing too many LQRs constitutes a loss of carrier and will trigger a reconnect. If the .Fl background flag is specified, all phone numbers are dialed at most once until a connection is made. The next number redial period specified with the .Dq set redial command is honoured, as is the reconnect tries value. If your redial value is less than the number of phone numbers specified, not all the specified numbers will be tried. To terminate the program, type .Bd -literal -offset indent PPP ON awfulhak> close ppp ON awfulhak> quit all .Ed .Pp A simple .Dq quit command will terminate the .Xr pppctl 8 or .Xr telnet 1 connection but not the .Nm program itself. You must use .Dq quit all to terminate .Nm as well. .Sh RECEIVING INCOMING PPP CONNECTIONS (Method 1) To handle an incoming .Em PPP connection request, follow these steps: .Bl -enum .It Make sure the modem and (optionally) .Pa /etc/rc.serial is configured correctly. .Bl -bullet -compact .It Use Hardware Handshake (CTS/RTS) for flow control. .It Modem should be set to NO echo back (ATE0) and NO results string (ATQ1). .El .Pp .It Edit .Pa /etc/ttys to enable a .Xr getty 8 on the port where the modem is attached. For example: .Pp .Dl ttyd1 "/usr/libexec/getty std.38400" dialup on secure .Pp Don't forget to send a .Dv HUP signal to the .Xr init 8 process to start the .Xr getty 8 : .Pp .Dl # kill -HUP 1 .It Create a .Pa /usr/local/bin/ppplogin file with the following contents: .Bd -literal -offset indent #! /bin/sh exec /usr/sbin/ppp -direct incoming .Ed .Pp Direct mode .Pq Fl direct lets .Nm work with stdin and stdout. You can also use .Xr pppctl 8 to connect to a configured diagnostic port, in the same manner as with client-side .Nm ppp . .Pp Here, the .Ar incoming section must be set up in .Pa /etc/ppp/ppp.conf . .Pp Make sure that the .Ar incoming section contains the .Dq allow users command as appropriate. .It Prepare an account for the incoming user. .Bd -literal ppp:xxxx:66:66:PPP Login User:/home/ppp:/usr/local/bin/ppplogin .Ed .Pp Refer to the manual entries for .Xr adduser 8 and .Xr vipw 8 for details. .It Support for IPCP Domain Name Server and NetBIOS Name Server negotiation can be enabled using the .Dq accept dns and .Dq set nbns commands. Refer to their descriptions below. .El .Pp .Sh RECEIVING INCOMING PPP CONNECTIONS (Method 2) This method differs in that we use .Nm ppp to authenticate the connection rather than .Xr login 1 : .Bl -enum .It Configure your default section in .Pa /etc/gettytab with automatic ppp recognition by specifying the .Dq pp capability: .Bd -literal default:\\ :pp=/usr/local/bin/ppplogin:\\ ..... .Ed .It Configure your serial device(s), enable a .Xr getty 8 and create .Pa /usr/local/bin/ppplogin as in the first three steps for method 1 above. .It Add either .Dq enable chap or .Dq enable pap .Pq or both to .Pa /etc/ppp/ppp.conf under the .Sq incoming label (or whatever label .Pa ppplogin uses). .It Create an entry in .Pa /etc/ppp/ppp.secret for each incoming user: .Bd -literal Pfredxxxx Pgeorgeyyyy .Ed .El .Pp Now, as soon as .Xr getty 8 detects a ppp connection (by recognising the HDLC frame headers), it runs .Dq /usr/local/bin/ppplogin . .Pp It is .Em VITAL that either PAP or CHAP are enabled as above. If they are not, you are allowing anybody to establish ppp session with your machine .Em without a password, opening yourself up to all sorts of potential attacks. .Sh AUTHENTICATING INCOMING CONNECTIONS Normally, the receiver of a connection requires that the peer authenticates itself. This may be done using .Xr login 1 , but alternatively, you can use PAP or CHAP. CHAP is the more secure of the two, but some clients may not support it. Once you decide which you wish to use, add the command .Sq enable chap or .Sq enable pap to the relevant section of .Pa ppp.conf . .Pp You must then configure the .Pa /etc/ppp/ppp.secret file. This file contains one line per possible client, each line containing up to four fields: .Bd -literal -offset indent name key [hisaddr [label]] .Ed .Pp The .Ar name and .Ar key specify the client as expected. If .Ar key is .Dq \&* and PAP is being used, .Nm will look up the password database .Pq Xr passwd 5 when authenticating. If the client does not offer a suitable response based on any .Ar name No / Ar key combination in .Pa ppp.secret , authentication fails. .Pp If authentication is successful, .Ar hisaddr .Pq if specified is used when negotiating IP numbers. See the .Dq set ifaddr command for details. .Pp If authentication is successful and .Ar label is specified, the current system label is changed to match the given .Ar label . This will change the subsequent parsing of the .Pa ppp.linkup and .Pa ppp.linkdown files. .Sh PPP OVER TCP (a.k.a Tunnelling) Instead of running .Nm over a serial link, it is possible to use a TCP connection instead by specifying a host and port as the device: .Pp .Dl set device ui-gate:6669 .Pp Instead of opening a serial device, .Nm will open a TCP connection to the given machine on the given socket. It should be noted however that .Nm doesn't use the telnet protocol and will be unable to negotiate with a telnet server. You should set up a port for receiving this .Em PPP connection on the receiving machine (ui-gate). This is done by first updating .Pa /etc/services to name the service: .Pp .Dl ppp-in 6669/tcp # Incoming PPP connections over TCP .Pp and updating .Pa /etc/inetd.conf to tell .Xr inetd 8 how to deal with incoming connections on that port: .Pp .Dl ppp-in stream tcp nowait root /usr/sbin/ppp ppp -direct ppp-in .Pp Don't forget to send a .Dv HUP signal to .Xr inetd 8 after you've updated .Pa /etc/inetd.conf . Here, we use a label named .Dq ppp-in . The entry in .Pa /etc/ppp/ppp.conf on ui-gate (the receiver) should contain the following: .Bd -literal -offset indent ppp-in: set timeout 0 set ifaddr 10.0.4.1 10.0.4.2 add 10.0.1.0/24 10.0.4.2 .Ed .Pp You may also want to enable PAP or CHAP for security. To enable PAP, add the following line: .Bd -literal -offset indent enable PAP .Ed .Pp You'll also need to create the following entry in .Pa /etc/ppp/ppp.secret : .Bd -literal -offset indent MyAuthName MyAuthPasswd .Ed .Pp If .Ar MyAuthPasswd is a .Pq Dq * , the password is looked up in the .Xr passwd 5 database. .Pp The entry in .Pa /etc/ppp/ppp.conf on awfulhak (the initiator) should contain the following: .Bd -literal -offset indent ui-gate: set escape 0xff set device ui-gate:ppp-in set dial set timeout 30 set log Phase Chat Connect hdlc LCP IPCP CCP tun set ifaddr 10.0.4.2 10.0.4.1 add 10.0.2.0/24 10.0.4.1 .Ed .Pp Again, if you're enabling PAP, you'll also need: .Bd -literal -offset indent set authname MyAuthName set authkey MyAuthKey .Ed .Pp We're assigning the address of 10.0.4.1 to ui-gate, and the address 10.0.4.2 to awfulhak. To open the connection, just type .Pp .Dl awfulhak # ppp -background ui-gate .Pp The result will be an additional "route" on awfulhak to the 10.0.2.0/24 network via the TCP connection, and an additional "route" on ui-gate to the 10.0.1.0/24 network. The networks are effectively bridged - the underlying TCP connection may be across a public network (such as the Internet), and the .Em PPP traffic is conceptually encapsulated (although not packet by packet) inside the TCP stream between the two gateways. The major disadvantage of this mechanism is that there are two "guaranteed delivery" mechanisms in place - the underlying TCP stream and whatever protocol is used over the .Em PPP link - probably TCP again. If packets are lost, both levels will get in each others way trying to negotiate sending of the missing packet. .Sh PACKET ALIASING The .Fl alias command line option enables packet aliasing. This allows the .Nm host to act as a masquerading gateway for other computers over a local area network. Outgoing IP packets are aliased so that they appear to come from the .Nm host, and incoming packets are de-aliased so that they are routed to the correct machine on the local area network. Packet aliasing allows computers on private, unregistered subnets to have Internet access, although they are invisible from the outside world. In general, correct .Nm operation should first be verified with packet aliasing disabled. Then, the .Fl alias option should be switched on, and network applications (web browser, .Xr telnet 1 , .Xr ftp 1 , .Xr ping 8 , .Xr traceroute 8 ) should be checked on the .Nm host. Finally, the same or similar applications should be checked on other computers in the LAN. If network applications work correctly on the .Nm host, but not on other machines in the LAN, then the masquerading software is working properly, but the host is either not forwarding or possibly receiving IP packets. Check that IP forwarding is enabled in .Pa /etc/rc.conf and that other machines have designated the .Nm host as the gateway for the LAN. .Sh PACKET FILTERING This implementation supports packet filtering. There are four kinds of filters; the .Em in filter, the .Em out filter, the .Em dial filter and the .Em alive filter. Here are the basics: .Bl -bullet .It A filter definition has the following syntax: .Pp set filter .Ar name .Ar rule-no .Ar action .Op Ar src_addr Ns Op / Ns Ar width .Op Ar dst_addr Ns Op / Ns Ar width [ .Ar proto .Op src Op Ar cmp No Ar port .Op dst Op Ar cmp No Ar port .Op estab .Op syn .Op finrst ] .Bl -enum .It .Ar Name should be one of .Sq in , .Sq out , .Sq dial or .Sq alive . .It .Ar Rule-no is a numeric value between .Sq 0 and .Sq 19 specifying the rule number. Rules are specified in numeric order according to .Ar rule-no , but only if rule .Sq 0 is defined. .It .Ar Action is either .Sq permit or .Sq deny . If a given packet matches the rule, the associated action is taken immediately. .It .Op Ar src_addr Ns Op / Ns Ar width and .Op Ar dst_addr Ns Op / Ns Ar width are the source and destination IP number specifications. If .Op / Ns Ar width is specified, it gives the number of relevant netmask bits, allowing the specification of an address range. .It .Ar Proto must be one of .Sq icmp , .Sq udp or .Sq tcp . .It .Ar Cmp is one of .Sq \< , .Sq \&eq or .Sq \> , meaning less-than, equal and greater-than respectively. .Ar Port can be specified as a numeric port or by service name from .Pa /etc/services . .It The .Sq estab , .Sq syn , and .Sq finrst flags are only allowed when .Ar proto is set to .Sq tcp , and represent the TH_ACK, TH_SYN and TH_FIN or TH_RST TCP flags respectively. .El .Pp .It Each filter can hold up to 20 rules, starting from rule 0. The entire rule set is not effective until rule 0 is defined, ie. the default is to allow everything through. .It If no rule is matched to a packet, that packet will be discarded (blocked). .It Use .Dq set filter Ar name No -1 to flush all rules. .El .Pp See .Pa /etc/ppp/ppp.conf.example . .Sh SETTING THE IDLE TIMER To check/set the idle timer, use the .Dq show bundle and .Dq set timeout commands: .Bd -literal -offset indent ppp ON awfulhak> set timeout 600 .Ed .Pp The timeout period is measured in seconds, the default value for which is 180 seconds .Pq or 3 min . To disable the idle timer function, use the command .Bd -literal -offset indent ppp ON awfulhak> set timeout 0 .Ed .Pp In .Fl ddial and .Fl direct modes, the idle timeout is ignored. In .Fl auto mode, when the idle timeout causes the .Em PPP session to be closed, the .Nm program itself remains running. Another trigger packet will cause it to attempt to re-establish the link. .Sh PREDICTOR-1 and DEFLATE COMPRESSION .Nm Ppp supports both Predictor type 1 and deflate compression. By default, .Nm will attempt to use (or be willing to accept) both compression protocols when the peer agrees .Pq or requests them . The deflate protocol is preferred by .Nm ppp . Refer to the .Dq disable and .Dq deny commands if you wish to disable this functionality. .Pp It is possible to use a different compression algorithm in each direction by using only one of .Dq disable deflate and .Dq deny deflate .Pq assuming that the peer supports both algorithms . .Pp By default, when negotiating DEFLATE, .Nm will use a window size of 15. Refer to the .Dq set deflate command if you wish to change this behaviour. .Pp A special algorithm called DEFLATE24 is also available, and is disabled and denied by default. This is exactly the same as DEFLATE except that it uses CCP ID 24 to negotiate. This allows .Nm to successfully negotiate DEFLATE with .Nm pppd version 2.3.*. .Sh CONTROLLING IP ADDRESS .Nm uses IPCP to negotiate IP addresses. Each side of the connection specifies the IP address that it's willing to use, and if the requested IP address is acceptable then .Nm returns ACK to the requester. Otherwise, .Nm returns NAK to suggest that the peer use a different IP address. When both sides of the connection agree to accept the received request (and send ACK), IPCP is set to the open state and a network level connection is established. To control this IPCP behaviour, this implementation has the .Dq set ifaddr command for defining the local and remote IP address: .Bd -literal -offset indent set ifaddr [src_addr [dst_addr [netmask [trigger_addr]]]] .Ed .Pp where, .Sq src_addr is the IP address that the local side is willing to use, .Sq dst_addr is the IP address which the remote side should use and .Sq netmask is the netmask that should be used. .Sq Src_addr defaults to the current .Xr hostname 1 , .Sq dst_addr defaults to 0.0.0.0, and .Sq netmask defaults to whatever mask is appropriate for .Sq src_addr . It is only possible to make .Sq netmask smaller than the default. The usual value is 255.255.255.255, as most kernels ignore the netmask of a POINTOPOINT interface. .Pp Some incorrect .Em PPP implementations require that the peer negotiates a specific IP address instead of .Sq src_addr . If this is the case, .Sq trigger_addr may be used to specify this IP number. This will not affect the routing table unless the other side agrees with this proposed number. .Bd -literal -offset indent set ifaddr 192.244.177.38 192.244.177.2 255.255.255.255 0.0.0.0 .Ed .Pp The above specification means: .Pp .Bl -bullet -compact .It I will first suggest that my IP address should be 0.0.0.0, but I will only accept an address of 192.244.177.38. .It I strongly insist that the peer uses 192.244.177.2 as his own address and won't permit the use of any IP address but 192.244.177.2. When the peer requests another IP address, I will always suggest that it uses 192.244.177.2. .It The routing table entry will have a netmask of 0xffffffff. .El .Pp This is all fine when each side has a pre-determined IP address, however it is often the case that one side is acting as a server which controls all IP addresses and the other side should obey the direction from it. In order to allow more flexible behaviour, `ifaddr' variable allows the user to specify IP address more loosely: .Pp .Dl set ifaddr 192.244.177.38/24 192.244.177.2/20 .Pp A number followed by a slash (/) represent the number of bits significant in the IP address. The above example signifies that: .Pp .Bl -bullet -compact .It I'd like to use 192.244.177.38 as my address if it is possible, but I'll also accept any IP address between 192.244.177.0 and 192.244.177.255. .It I'd like to make him use 192.244.177.2 as his own address, but I'll also permit him to use any IP address between 192.244.176.0 and 192.244.191.255. .It As you may have already noticed, 192.244.177.2 is equivalent to saying 192.244.177.2/32. .It As an exception, 0 is equivalent to 0.0.0.0/0, meaning that I have no preferred IP address and will obey the remote peers selection. When using zero, no routing table entries will be made until a connection is established. .It 192.244.177.2/0 means that I'll accept/permit any IP address but I'll try to insist that 192.244.177.2 be used first. .El .Pp .Sh CONNECTING WITH YOUR INTERNET SERVICE PROVIDER The following steps should be taken when connecting to your ISP: .Bl -enum .It Describe your providers phone number(s) in the dial script using the .Dq set phone command. This command allows you to set multiple phone numbers for dialing and redialing separated by either a pipe (|) or a colon (:) .Bd -literal -offset indent set phone "111[|222]...[:333[|444]...]... .Ed .Pp Numbers after the first in a pipe-separated list are only used if the previous number was used in a failed dial or login script. Numbers separated by a colon are used sequentially, irrespective of what happened as a result of using the previous number. For example: .Bd -literal -offset indent set phone "1234567|2345678:3456789|4567890" .Ed .Pp Here, the 1234567 number is attempted. If the dial or login script fails, the 2345678 number is used next time, but *only* if the dial or login script fails. On the dial after this, the 3456789 number is used. The 4567890 number is only used if the dial or login script using the 3456789 fails. If the login script of the 2345678 number fails, the next number is still the 3456789 number. As many pipes and colons can be used as are necessary (although a given site would usually prefer to use either the pipe or the colon, but not both). The next number redial timeout is used between all numbers. When the end of the list is reached, the normal redial period is used before starting at the beginning again. The selected phone number is substituted for the \\\\T string in the .Dq set dial command (see below). .It Set up your redial requirements using .Dq set redial . For example, if you have a bad telephone line or your provider is usually engaged (not so common these days), you may want to specify the following: .Bd -literal -offset indent set redial 10 4 .Ed .Pp This says that up to 4 phone calls should be attempted with a pause of 10 seconds before dialing the first number again. .It Describe your login procedure using the .Dq set dial and .Dq set login commands. The .Dq set dial command is used to talk to your modem and establish a link with your ISP, for example: .Bd -literal -offset indent set dial "ABORT BUSY ABORT NO\\\\sCARRIER TIMEOUT 4 \\"\\" \e ATZ OK-ATZ-OK ATDT\\\\T TIMEOUT 60 CONNECT" .Ed .Pp This modem "chat" string means: .Bl -bullet .It Abort if the string "BUSY" or "NO CARRIER" are received. .It Set the timeout to 4 seconds. .It Expect nothing. .It Send ATZ. .It Expect OK. If that's not received within the 4 second timeout, send ATZ and expect OK. .It Send ATDTxxxxxxx where xxxxxxx is the next number in the phone list from above. .It Set the timeout to 60. .It Wait for the CONNECT string. .El .Pp Once the connection is established, the login script is executed. This script is written in the same style as the dial script, but care should be taken to avoid having your password logged: .Bd -literal -offset indent set authkey MySecret set login "TIMEOUT 15 login:-\\\\r-login: awfulhak \e word: \\\\P ocol: PPP HELLO" .Ed .Pp This login "chat" string means: .Bl -bullet .It Set the timeout to 15 seconds. .It Expect "login:". If it's not received, send a carriage return and expect "login:" again. .It Send "awfulhak" .It Expect "word:" (the tail end of a "Password:" prompt). .It Send whatever our current .Ar authkey value is set to. .It Expect "ocol:" (the tail end of a "Protocol:" prompt). .It Send "PPP". .It Expect "HELLO". .El .Pp The .Dq set authkey command is logged specially (when using .Ar command logging) so that the actual password is not compromised (it is logged as .Sq ******** Ns ), and the '\\P' is logged when .Ar chat logging is active rather than the actual password. .Pp Login scripts vary greatly between ISPs. If you're setting one up for the first time, .Em ENABLE CHAT LOGGING so that you can see if your script is behaving as you expect. .It Use .Dq set line and .Dq set speed to specify your serial line and speed, for example: .Bd -literal -offset indent set line /dev/cuaa0 set speed 115200 .Ed .Pp Cuaa0 is the first serial port on FreeBSD. If you're running .Nm on OpenBSD, cua00 is the first. A speed of 115200 should be specified if you have a modem capable of bit rates of 28800 or more. In general, the serial speed should be about four times the modem speed. .It Use the .Dq set ifaddr command to define the IP address. .Bl -bullet .It If you know what IP address your provider uses, then use it as the remote address (dst_addr), otherwise choose something like 10.0.0.2/0 (see below). .It If your provider has assigned a particular IP address to you, then use it as your address (src_addr). .It If your provider assigns your address dynamically, choose a suitably unobtrusive and unspecific IP number as your address. 10.0.0.1/0 would be appropriate. The bit after the / specifies how many bits of the address you consider to be important, so if you wanted to insist on something in the class C network 1.2.3.0, you could specify 1.2.3.1/24. .It If you find that your ISP accepts the first IP number that you suggest, specify third and forth arguments of .Dq 0.0.0.0 . This will force your ISP to assign a number. (The third argument will be ignored as it is less restrictive than the default mask for your .Sq src_addr . .El .Pp An example for a connection where you don't know your IP number or your ISPs IP number would be: .Bd -literal -offset indent set ifaddr 10.0.0.1/0 10.0.0.2/0 0.0.0.0 0.0.0.0 .Ed .Pp .It In most cases, your ISP will also be your default router. If this is the case, add the line .Bd -literal -offset indent add default HISADDR .Ed .Pp to .Pa /etc/ppp/ppp.conf . .Pp This tells .Nm to add a default route to whatever the peer address is .Pq 10.0.0.2 in this example . This route is .Sq sticky , meaning that should the value of .Dv HISADDR change, the route will be updated accordingly. .Pp Previous versions of .Nm required a similar entry in the .Pa /etc/ppp/ppp.linkup file. Since the advent of .Sq sticky routes , his is no longer required. .It If your provider requests that you use PAP/CHAP authentication methods, add the next lines to your .Pa /etc/ppp/ppp.conf file: .Bd -literal -offset indent set authname MyName set authkey MyPassword .Ed .Pp Both are accepted by default, so .Nm will provide whatever your ISP requires. .Pp It should be noted that a login script is rarely (if ever) required when PAP or CHAP are in use. .It Ask your ISP to authenticate your nameserver address(es) with the line .Bd -literal -offset indent enable dns .Ed Do .Em NOT do this if you are running an local DNS, as .Nm will simply circumvent its use by entering some nameserver lines in .Pa /etc/resolv.conf . .El .Pp Please refer to .Pa /etc/ppp/ppp.conf.sample and .Pa /etc/ppp/ppp.linkup.sample for some real examples. The pmdemand label should be appropriate for most ISPs. .Sh LOGGING FACILITY .Nm Ppp is able to generate the following log info either via .Xr syslog 3 or directly to the screen: .Bl -column SMMMMMM -offset indent .It Li Async Dump async level packet in hex .It Li CBCP Generate CBCP (CallBack Control Protocol) logs .It Li CCP Generate a CCP packet trace .It Li Chat Generate Chat script trace log .It Li Command Log commands executed .It Li Connect Generate complete Chat log .It Li Debug Log debug information .It Li HDLC Dump HDLC packet in hex .It Li ID0 Log all function calls specifically made as user id 0. .It Li IPCP Generate an IPCP packet trace .It Li LCP Generate an LCP packet trace .It Li LQM Generate LQR report .It Li Phase Phase transition log output .It Li TCP/IP Dump all TCP/IP packets .It Li Timer Log timer manipulation .It Li TUN Include the tun device on each log line .It Li Warning Output to the terminal device. If there is currently no terminal, output is sent to the log file using LOG_WARNING. .It Li Error Output to both the terminal device and the log file using LOG_ERROR. .It Li Alert Output to the log file using LOG_ALERT .El .Pp The .Dq set log command allows you to set the logging output level. Multiple levels can be specified on a single command line. The default is equivalent to .Dq set log Phase . .Pp It is also possible to log directly to the screen. The syntax is the same except that the word .Dq local should immediately follow .Dq set log . The default is .Dq set log local (ie. only the un-maskable warning, error and alert output). .Pp If The first argument to .Dq set log Op local begins with a '+' or a '-' character, the current log levels are not cleared, for example: .Bd -literal -offset indent PPP ON awfulhak> set log phase PPP ON awfulhak> show log Log: Phase Warning Error Alert Local: Warning Error Alert PPP ON awfulhak> set log +tcp/ip -warning PPP ON awfulhak> set log local +command PPP ON awfulhak> show log Log: Phase TCP/IP Warning Error Alert Local: Command Warning Error Alert .Ed .Pp Log messages of level Warning, Error and Alert are not controllable using .Dq set log Op local . .Pp The .Ar Warning level is special in that it will not be logged if it can be displayed locally. .Sh SIGNAL HANDLING .Nm Ppp deals with the following signals: .Bl -tag -width XX .It INT Receipt of this signal causes the termination of the current connection (if any). This will cause .Nm to exit unless it is in .Fl auto or .Fl ddial mode. .It HUP, TERM & QUIT These signals tell .Nm to exit. .It USR2 This signal, tells .Nm to close any existing server socket, dropping all existing diagnostic connections. .El .Pp .Sh MULTI-LINK PPP If you wish to use more than one physical link to connect to a .Em PPP peer, that peer must also understand the .Em MULTI-LINK PPP protocol. Refer to RFC 1990 for specification details. .Pp The peer is identified using a combination of his .Dq endpoint discriminator and his .Dq authentication id . Either or both of these may be specified. It is recommended that at least one is specified, otherwise there is no way of ensuring that all links are actually connected to the same peer program, and some confusing lock-ups may result. Locally, these identification variables are specified using the .Dq set enddisc and .Dq set authname commands. The .Sq authname .Pq and Sq authkey must be agreed in advance with the peer. .Pp Multi-link capabilities are enabled using the .Dq set mrru command (set maximum reconstructed receive unit). Once multi-link is enabled, .Nm will attempt to negotiate a multi-link connection with the peer. .Pp By default, only one .Sq link is available .Pq called Sq deflink . To create more links, the .Dq clone command is used. This command will clone existing links, where all characteristics are the same except: .Bl -enum .It The new link has its own name as specified on the .Dq clone command line. .It The new link is an .Sq interactive link. It's mode may subsequently be changed using the .Dq set mode command. .It The new link is in a .Sq closed state. .El .Pp A summary of all available links can be seen using the .Dq show links command. .Pp Once a new link has been created, command usage varies. All link specific commands must be prefixed with the .Dq link Ar name command, specifying on which link the command is to be applied. When only a single link is available, .Nm is smart enough not to require the .Dq link Ar name prefix. .Pp Some commands can still be used without specifying a link - resulting in an operation at the .Sq bundle level. For example, once two or more links are available, the command .Dq show ccp will show CCP configuration and statistics at the multi-link level, and .Dq link deflink show ccp will show the same information at the .Dq deflink link level. .Pp Armed with this information, the following configuration might be used: .Pp .Bd -literal -offset indent mp: set timeout 0 set log phase chat set device /dev/cuaa0 /dev/cuaa1 /dev/cuaa2 set phone "123456789" set dial "ABORT BUSY ABORT NO\\sCARRIER TIMEOUT 5 \\"\\" ATZ \e OK-AT-OK \\\\dATDT\\\\T TIMEOUT 45 CONNECT" set login set ifaddr 10.0.0.1/0 10.0.0.2/0 set authname ppp set authkey ppppassword set mrru 1500 clone 1,2,3 link deflink remove .Ed .Pp Note how all cloning is done at the end of the configuration. Usually, the link will be configured first, then cloned. If you wish all links to be up all the time, you can add the following line to the end of your configuration. .Pp .Bd -literal -offset indent link 1,2,3 set mode ddial .Ed .Pp If you want the links to dial on demand, this command could be used: .Pp .Bd -literal -offset indent link * set mode auto .Ed .Pp Links may be tied to specific names by removing the .Dq set device line above, and specifying the following after the .Dq clone command: .Pp .Bd -literal -offset indent link 1 set device /dev/cuaa0 link 2 set device /dev/cuaa1 link 3 set device /dev/cuaa2 .Ed .Pp Use the .Dq help command to see which commands require context (using the .Dq link command), which have optional context and which should not have any context. .Pp When .Nm has negotiated .Em MULTI-LINK mode with the peer, it creates a local domain socket in the .Pa /var/run directory. This socket is used to pass link information (including the actual link file descriptor) between different .Nm invocations. This facilitates .Nm ppp Ns No s ability to be run from a .Xr getty 8 or directly from .Pa /etc/gettydefs (using the .Sq pp= capability), without needing to have initial control of the serial line. Once .Nm negotiates multi-link mode, it will pass its open link to any already running process. If there is no already running process, .Nm will act as the master, creating the socket and listening for new connections. .Sh PPP COMMAND LIST This section lists the available commands and their effect. They are usable either from an interactive .Nm session, from a configuration file or from a .Xr pppctl 8 or .Xr telnet 1 session. .Bl -tag -width XX .It accept|deny|enable|disable Ar option.... These directives tell .Nm how to negotiate the initial connection with the peer. Each .Dq option has a default of either accept or deny and enable or disable. .Dq Accept means that the option will be ACK'd if the peer asks for it. .Dq Deny means that the option will be NAK'd if the peer asks for it. .Dq Enable means that the option will be requested by us. .Dq Disable means that the option will not be requested by us. .Pp .Dq Option may be one of the following: .Bl -tag -width XX .It acfcomp Default: Enabled and Accepted. ACFComp stands for Address and Control Field Compression. Non LCP packets usually have very similar address and control fields - making them easily compressible. .It chap Default: Disabled and Accepted. CHAP stands for Challenge Handshake Authentication Protocol. Only one of CHAP and PAP (below) may be negotiated. With CHAP, the authenticator sends a "challenge" message to its peer. The peer uses a one-way hash function to encrypt the challenge and sends the result back. The authenticator does the same, and compares the results. The advantage of this mechanism is that no passwords are sent across the connection. A challenge is made when the connection is first made. Subsequent challenges may occur. If you want to have your peer authenticate itself, you must .Dq enable chap . in .Pa /etc/ppp/ppp.conf , and have an entry in .Pa /etc/ppp/ppp.secret for the peer. .Pp When using CHAP as the client, you need only specify .Dq AuthName and .Dq AuthKey in .Pa /etc/ppp/ppp.conf . CHAP is accepted by default. Some .Em PPP implementations use "MS-CHAP" rather than MD5 when encrypting the challenge. MS-CHAP is a combination of MD4 and DES. If .Nm was built on a machine with DES libraries available, it will respond to MS-CHAP authentication requests, but will never request them. .It deflate Default: Enabled and Accepted. This option decides if deflate compression will be used by the Compression Control Protocol (CCP). This is the same algorithm as used by the .Xr gzip 1 program. Note: There is a problem negotiating .Ar deflate capabilities with .Xr pppd 8 - a .Em PPP implementation available under many operating systems. .Nm Pppd (version 2.3.1) incorrectly attempts to negotiate .Ar deflate compression using type .Em 24 as the CCP configuration type rather than type .Em 26 as specified in .Pa rfc1979 . Type .Ar 24 is actually specified as .Dq PPP Magna-link Variable Resource Compression in .Pa rfc1975 Ns No ! .Nm Ppp is capable of negotiating with .Nm pppd , but only if .Dq deflate24 is .Ar enable Ns No d and .Ar accept Ns No ed . .It deflate24 Default: Disabled and Denied. This is a variance of the .Ar deflate option, allowing negotiation with the .Xr pppd 8 program. Refer to the .Ar deflate section above for details. It is disabled by default as it violates .Pa rfc1975 . .It dns Default: Disabled and Denied. This option allows DNS negotiation. .Pp If .Dq enable Ns No d, .Nm will request that the peer confirms the entries in .Pa /etc/resolv.conf . If the peer NAKs our request (suggesting new IP numbers), .Pa /etc/resolv.conf is updated and another request is sent to confirm the new entries. .Pp If .Dq accept Ns No ed, .Nm will answer any DNS queries requested by the peer rather than rejecting them. The answer is taken from .Pa /etc/resolv.conf unless the .Dq set dns command is used as an override. .It lqr Default: Disabled and Accepted. This option decides if Link Quality Requests will be sent or accepted. LQR is a protocol that allows .Nm to determine that the link is down without relying on the modems carrier detect. When LQR is enabled, .Nm sends the .Em QUALPROTO option (see .Dq set lqrperiod below) as part of the LCP request. If the peer agrees, both sides will exchange LQR packets at the agreed frequency, allowing detailed link quality monitoring by enabling LQM logging. If the peer doesn't agree, ppp will send ECHO LQR requests instead. These packets pass no information of interest, but they .Em MUST be replied to by the peer. .Pp Whether using LQR or ECHO LQR, .Nm will abruptly drop the connection if 5 unacknowledged packets have been sent rather than sending a 6th. A message is logged at the .Em PHASE level, and any appropriate .Dq reconnect values are honoured as if the peer were responsible for dropping the connection. .It pap Default: Disabled and Accepted. PAP stands for Password Authentication Protocol. Only one of PAP and CHAP (above) may be negotiated. With PAP, the ID and Password are sent repeatedly to the peer until authentication is acknowledged or the connection is terminated. This is a rather poor security mechanism. It is only performed when the connection is first established. If you want to have your peer authenticate itself, you must .Dq enable pap . in .Pa /etc/ppp/ppp.conf , and have an entry in .Pa /etc/ppp/ppp.secret for the peer (although see the .Dq passwdauth option below). .Pp When using PAP as the client, you need only specify .Dq AuthName and .Dq AuthKey in .Pa /etc/ppp/ppp.conf . PAP is accepted by default. .It pred1 Default: Enabled and Accepted. This option decides if Predictor 1 compression will be used by the Compression Control Protocol (CCP). .It protocomp Default: Enabled and Accepted. This option is used to negotiate PFC (Protocol Field Compression), a mechanism where the protocol field number is reduced to one octet rather than two. .It shortseq Default: Enabled and Accepted. This option determines if .Nm will request and accept requests for short .Pq 12 bit sequence numbers when negotiating multi-link mode. This is only applicable if our MRRU is set (thus enabling multi-link). .It vjcomp Default: Enabled and Accepted. This option determines if Van Jacobson header compression will be used. .El .Pp The following options are not actually negotiated with the peer. Therefore, accepting or denying them makes no sense. .Bl -tag -width XX .It idcheck Default: Enabled. When .Nm exchanges low-level LCP, CCP and IPCP configuration traffic, the .Em Identifier field of any replies is expected to be the same as that of the request. By default, .Nm drops any reply packets that do not contain the expected identifier field, reporting the fact at the respective log level. If .Ar idcheck is disabled, .Nm will ignore the identifier field. .It loopback Default: Enabled. When .Ar loopback is enabled, .Nm will automatically loop back packets being sent out with a destination address equal to that of the .Em PPP interface. If disabled, .Nm will send the packet, probably resulting in an ICMP redirect from the other end. It is convenient to have this option enabled when the interface is also the default route as it avoids the necessity of a loopback route. .It passwdauth Default: Disabled. Enabling this option will tell the PAP authentication code to use the password database (see .Xr passwd 5 ) to authenticate the caller if they cannot be found in the .Pa /etc/ppp/ppp.secret file. .Pa /etc/ppp/ppp.secret is always checked first. If you wish to use passwords from .Xr passwd 5 , but also to specify an IP number or label for a given client, use .Dq \&* as the client password in .Pa /etc/ppp/ppp.secret . .It proxy Default: Disabled. Enabling this option will tell .Nm to proxy ARP for the peer. .It sroutes Default: Enabled. When the .Dq add command is used with the .Dv HISADDR or .Dv MYADDR values, entries are stored in the .Sq stick route list. Each time .Dv HISADDR or .Dv MYADDR change, this list is re-applied to the routing table. .Pp Disabling this option will prevent the re-application of sticky routes, although the .Sq stick route list will still be maintained. .It throughput Default: Enabled. This option tells .Nm to gather throughput statistics. Input and output is sampled over a rolling 5 second window, and current, best and total figures are retained. This data is output when the relevant .Em PPP layer shuts down, and is also available using the .Dq show command. Throughput statistics are available at the .Dq IPCP and .Dq modem levels. .It utmp Default: Enabled. Normally, when a user is authenticated using PAP or CHAP, and when .Nm is running in .Fl direct mode, an entry is made in the utmp and wtmp files for that user. Disabling this option will tell .Nm not to make any utmp or wtmp entries. This is usually only necessary if you require the user to both login and authenticate themselves. .El .Pp .It add[!] Ar dest[/nn] [mask] gateway .Ar Dest is the destination IP address. The netmask is specified either as a number of bits with .Ar /nn or as an IP number using .Ar mask . .Ar 0 0 or simply .Ar 0 with no mask refers to the default route. It is also possible to use the literal name .Sq default instead of .Ar 0 . .Ar Gateway is the next hop gateway to get to the given .Ar dest machine/network. Refer to the .Xr route 8 command for further details. .Pp It is possible to use the symbolic names .Sq MYADDR or .Sq HISADDR as the destination, and either .Sq HISADDR or .Sq INTERFACE as the .Ar gateway . .Sq MYADDR is replaced with the interface address, .Sq HISADDR is replaced with the interface destination address and .Sq INTERFACE is replaced with the current interface name. If the interfaces destination address has not yet been assigned .Pq via Dq set ifaddr , the current .Sq INTERFACE is used instead of .Sq HISADDR . .Pp If the .Ar add! command is used .Pq note the trailing Dq \&! , then if the route already exists, it will be updated as with the .Sq route change command (see .Xr route 8 for further details). .Pp Routes that contain the .Dq HISADDR or .Dq MYADDR constants are considered .Sq sticky . They are stored in a list (use .Dq show ipcp to see the list), and each time the value of .Dv HISADDR or .Dv MYADDR changes, the appropriate routing table entries are updated. This facility may be disabled using .Dq disable sroutes . .It allow Ar command Op Ar args This command controls access to .Nm and its configuration files. It is possible to allow user-level access, depending on the configuration file label and on the mode that .Nm is being run in. For example, you may wish to configure .Nm so that only user .Sq fred may access label .Sq fredlabel in .Fl background mode. .Pp User id 0 is immune to these commands. .Bl -tag -width XX .It allow user[s] Ar logname... By default, only user id 0 is allowed access to .Nm ppp . If this command is used, all of the listed users are allowed access to the section in which the .Dq allow users command is found. The .Sq default section is always checked first (even though it is only ever automatically loaded at startup). Each successive .Dq allow users command overrides the previous one, so it's possible to allow users access to everything except a given label by specifying default users in the .Sq default section, and then specifying a new user list for that label. .Pp If user .Sq * is specified, access is allowed to all users. .It allow mode[s] Ar modelist... By default, access using any .Nm mode is possible. If this command is used, it restricts the access mode allowed to load the label under which this command is specified. Again, as with the .Dq allow users command, each .Dq allow modes command overrides the previous, and the .Sq default section is always checked first. .Pp Possible modes are: .Sq interactive , .Sq auto , .Sq direct , .Sq dedicated , .Sq ddial , .Sq background and .Sq * . .Pp When running in multi-link mode, a section can be loaded if it allows .Em any of the currently existing line modes. .El .Pp .It alias Ar command Op Ar args This command allows the control of the aliasing (or masquerading) facilities that are built into .Nm ppp . If aliasing is enabled on your system (it may be omitted at compile time), the following commands are possible: .Bl -tag -width XX .It alias enable [yes|no] This command either switches aliasing on or turns it off. The .Fl alias command line flag is synonymous with .Dq alias enable yes . .It alias port Op Ar proto targetIP:targetPORT [aliasIP:]aliasPORT This command allows us to redirect connections arriving at .Ar aliasPORT for machine .Ar aliasIP to .Ar targetPORT on .Ar targetIP . .Ar Proto may be either .Sq tcp or .Sq udp , and only connections of the given protocol are matched. This option is useful if you wish to run things like Internet phone on the machines behind your gateway. .It alias addr Op Ar addr_local addr_alias This command allows data for .Ar addr_alias to be redirected to .Ar addr_local . It is useful if you own a small number of real IP numbers that you wish to map to specific machines behind your gateway. .It alias deny_incoming [yes|no] If set to yes, this command will refuse all incoming connections by dropping the packets in much the same way as a firewall would. .It alias help|? This command gives a summary of available alias commands. .It alias log [yes|no] This option causes various aliasing statistics and information to be logged to the file .Pa /var/log/alias.log . .It alias same_ports [yes|no] When enabled, this command will tell the alias library attempt to avoid changing the port number on outgoing packets. This is useful if you want to support protocols such as RPC and LPD which require connections to come from a well known port. .It alias use_sockets [yes|no] When enabled, this option tells the alias library to create a socket so that it can guarantee a correct incoming ftp data or IRC connection. .It alias unregistered_only [yes|no] Only alter outgoing packets with an unregistered source ad- dress. According to RFC 1918, unregistered source addresses are 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16. .El .Pp These commands are also discussed in the file .Pa README.alias which comes with the source distribution. .Pp .It [!]bg Ar command The given .Ar command is executed in the background with the following words replaced: .Bl -tag -width PEER_ENDDISC .It Li AUTHNAME This is replaced with the local .Ar authname value. See the .Dq set authname command below. .It Li ENDDISC This is replaced with the local endpoint discriminator value. See the .Dq set enddisc command below. .It Li HISADDR This is replaced with the peers IP number. .It Li INTERFACE This is replaced with the name of the interface that's in use. .It Li LABEL This is replaced with the last label name used. A label may be specified on the .Nm command line, via the .Dq load or .Dq dial commands and in the .Pa ppp.secret file. .It Li MYADDR This is replaced with the IP number assigned to the local interface. .It Li PEER_ENDDISC This is replaced with the value of the peers endpoint discriminator. .It Li USER This is replaced with the username that has been authenticated with PAP or CHAP. Normally, this variable is assigned only in -direct mode. This value is available irrespective of whether utmp logging is enabled. .El .Pp If you wish to pause .Nm while the command executes, use the .Dq shell command instead. .It clear modem|ipcp Op current|overall|peak... Clear the specified throughput values at either the .Dq modem or .Dq ipcp level. If .Dq modem is specified, context must be given (see the .Dq link command below). If no second argument is given, all values are cleared. .It clone Ar name[,name]... Clone the specified link, creating one or more new links according to the .Ar name argument(s). This command must be used from the .Dq link command below unless you've only got a single link (in which case that link becomes the default). Links may be removed using the .Dq remove command below. .Pp The default link name is .Dq deflink . .It close Op lcp|ccp[!] If no arguments are given, the relevant protocol layers will be brought down and the link will be closed. If .Dq lcp is specified, the LCP layer is brought down, but .Nm will not bring the link offline. It is subsequently possible to use .Dq term .Pq see below to talk to the peer machine if, for example, something like .Dq slirp is being used. If .Dq ccp is specified, only the relevant compression layer is closed. If the .Dq \&! is used, the compression layer will remain in the closed state, otherwise it will re-enter the STOPPED state, waiting for the peer to initiate further CCP negotiation. In any event, this command does not disconnect the user from .Nm or exit .Nm ppp . See the .Dq quit command below. .It delete[!] Ar dest This command deletes the route with the given .Ar dest IP address. If .Ar dest is specified as .Sq ALL , all non-direct entries in the routing table for the current interface, and all .Sq sticky route entries are deleted. If .Ar dest is specified as .Sq default , the default route is deleted. .Pp If the .Ar delete! command is used .Pq note the trailing Dq \&! , .Nm will not complain if the route does not already exist. .It dial|call Op Ar label When used with no argument, this command is the same as the .Dq open command. When .Ar label is specified, a .Dq load will be done first. .It down Op Ar lcp|ccp Bring the relevant layer down ungracefully, as if the underlying layer had become unavailable. It's not considered polite to use this command on a Finite State Machine that's in the OPEN state. If no arguments are supplied, the entire link is closed (or if no context is given, all links are terminated). If .Sq lcp is specified, the .Em LCP layer is terminated but the modem is not brought offline and the link is not closed. If .Sq ccp is specified, only the relevant compression layer(s) are terminated. .It help|? Op Ar command Show a list of available commands. If .Ar command is specified, show the usage string for that command. .It [data]link Ar name[,name...] command Op Ar args This command may prefix any other command if the user wishes to specify which link the command should affect. This is only applicable after multiple links have been created in Multi-link mode using the .Dq clone command. .Pp .Ar Name specifies the name of an existing link. If .Ar name is a comma separated list, .Ar command is executed on each link. If .Ar name is .Dq * , .Ar command is executed on all links. .It load Op Ar label Load the given .Ar label from the .Pa ppp.conf file. If .Ar label is not given, the .Ar default label is used. .It open Op lcp|ccp|ipcp This is the opposite of the .Dq close command. Using .Dq open with no arguments is the same as using .Dq dial with no arguments, where all closed links are brought up (some auto links may not come up based on the .Dq set autoload command) using the current configuration. .Pp If the .Dq lcp while the LCP layer is already open, LCP will be renegotiated. This allows various LCP options to be changed, after which .Dq open lcp can be used to put them into effect. After renegotiating LCP, any agreed authentication will also take place. .Pp If the .Dq ccp argument is used, the relevant compression layer is opened. Again, if it is already open, it will be renegotiated. .Pp If the .Dq ipcp argument is used, the link will be brought up as normal, but if IPCP is already open, it will be renegotiated and the network interface will be reconfigured. .Pp It is probably not good practice to re-open the PPP state machines like this as it's possible that the peer will not behave correctly. It .Em is however useful as a way of forcing the CCP or VJ dictionaries to be reset. .It passwd Ar pass Specify the password required for access to the full .Nm command set. This password is required when connecting to the diagnostic port (see the .Dq set server command). .Ar Pass is specified on the .Dq set server command line. The value of .Ar pass is not logged when .Ar command logging is active, instead, the literal string .Sq ******** is logged. .It quit|bye [all] If .Dq quit is executed from the controlling connection or from a command file, ppp will exit after closing all connections. Otherwise, if the user is connected to a diagnostic socket, the connection is simply dropped. .Pp If the .Ar all argument is given, .Nm will exit despite the source of the command after closing all existing connections. .It remove|rm This command removes the given link. It is only really useful in multi-link mode. A link must be in the .Dv CLOSED state before it is removed. .It rename|mv Ar name This command renames the given link to .Ar name . It will fail if .Ar name is already used by another link. .Pp The default link name is .Sq deflink . Renaming it to .Sq modem , .Sq cuaa0 or .Sq USR may make the log file more readable. .It save This option is not (yet) implemented. .It set[up] Ar var value This option allows the setting of any of the following variables: .Bl -tag -width XX .It set accmap Ar hex-value ACCMap stands for Asynchronous Control Character Map. This is always negotiated with the peer, and defaults to a value of 00000000 in hex. This protocol is required to defeat hardware that depends on passing certain characters from end to end (such as XON/XOFF etc). .Pp For the XON/XOFF scenario, use .Dq set accmap 000a0000 . .It set authkey|key Ar value This sets the authentication key (or password) used in client mode PAP or CHAP negotiation to the given value. It can also be used to specify the password to be used in the dial or login scripts in place of the '\\P' sequence, preventing the actual password from being logged. If .Ar command logging is in effect, .Ar value is logged as .Sq ******** for security reasons. .It set authname Ar id This sets the authentication id used in client mode PAP or CHAP negotiation. .Pp If used in .Fl direct mode with PAP or CHAP enabled, .Ar id is used in the initial authentication request and is normally set to the local machine name. .It set autoload Ar max-duration max-load [min-duration min-load] These settings apply only in multi-link mode and all default to zero. When more than one .Ar demand-dial .Pq also known as Fl auto mode link is available, only the first link is made active when .Nm first reads data from the tun device. The next .Ar demand-dial link will be opened only when at least .Ar max-load packets have been in the send queue for .Ar max-duration seconds. Because both values default to zero, .Ar demand-dial links will simply come up one at a time by default. .Pp If two or more links are open, at least one of which is a .Ar demand-dial link, a .Ar demand-dial link will be closed when there is less than .Ar min-packets in the queue for more than .Ar min-duration . If .Ar min-duration is zero, this timer is disabled. Because both values default to zero, .Ar demand-dial links will stay active until the bundle idle timer expires. .It set callback [none|auth|cbcp|E.164 *|number[,number]...]... If no arguments are given, callback is disabled, otherwise, .Nm will request (or in .Ar direct mode, will accept) one of the given protocols. If a request is NAK'd .Nm will request another, until no options remain at which point .Nm will terminate negotiations. The options are as follows (in this order of preference): .Pp .Bl -tag .It auth The callee is expected to decide the callback number based on authentication. If .Nm is the callee, the number should be specified as the fifth field of the peers entry in .Pa /etc/ppp/ppp.secret . .It cbcp Microsofts callback control protocol is used. See .Dq set cbcp below. .It E.164 *|number[,number]... The caller specifies the .Ar number . If .Nm is the callee, .Ar number should be either a comma seperated list of allowable numbers or a .Dq \&* , meaning any number is permitted. If .Nm is the caller, only a single number should be specified. .Pp Note, this option is very unsafe when used with a .Dq \&* as a malicious caller can tell .Nm to call any (possibly international) number without first authenticating themselves. .It none If the peer does not wish to do callback at all, .Nm will accept the fact and continue without callback rather than terminating the connection. .El .Pp .It set cbcp Op *|number[,number]... Op delay Op retry If no arguments are given, CBCP (Microsofts CallBack Control Protocol) is disabled - ie, configuring CBCP in the .Dq set callback command will result in .Nm requesting no callback in the CBCP phase. Otherwise, .Nm attempts to use the given phone .Ar number Ns No (s). .Pp In server mode .Pq Fl direct , .Nm will insist that the client uses one of these numbers, unless .Dq \&* is used in which case the client is expected to specify the number. .Pp In client mode, .Nm will attempt to use one of the given numbers (whichever it finds to be agreeable with the peer), or if .Dq \&* is specified, .Nm will expect the peer to specify the number. .It set choked Op Ar timeout This sets the number of seconds that .Nm will keep a choked output queue before dropping all pending output packets. If .Ar timeout is less than or equal to zero or if .Ar timeout isn't specified, it is set to the default value of .Em 120 seconds . .Pp A choked output queue occurs when .Nm has read a certain number of packets from the local network for transmission, but cannot send the data due to link failure (the peer is busy etc.). .Nm Ppp will not read packets indefinitely. Instead, it reads up to .Em 20 packets (or .Em 20 No + .Em nlinks No * .Em 2 packets in multi-link mode), then stops reading the network interface until either .Ar timeout seconds have passed or at least one packet has been sent. .Pp If .Ar timeout seconds pass, all pending output packets are dropped. .It set ctsrts|crtscts on|off This sets hardware flow control. Hardware flow control is .Ar on by default. .It set deflate Ar out-winsize Op Ar in-winsize This sets the DEFLATE algorithms default outgoing and incoming window sizes. Both .Ar out-winsize and .Ar in-winsize must be values between .Em 8 and .Em 15 . If .Ar in-winsize is specified, .Nm will insist that this window size is used and will not accept any other values from the peer. .It set dns Op Ar primary Op Ar secondary This command specifies DNS overrides for the .Dq accept dns command. Refer to the .Dq accept command description above for details. This command does not affect the IP numbers requested using .Dq enable dns . .It set device|line Ar value[,value...] This sets the device(s) to which .Nm will talk to the given .Dq value . All serial device names are expected to begin with .Pa /dev/ . If .Dq value does not begin with .Pa /dev/ , it must either begin with an exclamation mark .Pq Dq \&! or be of the format .Dq host:port . .Pp If it begins with an exclamation mark, the rest of the device name is treated as a program name, and that program is executed when the device is opened. Standard input, output and error are fed back to .Nm and are read and written as if they were a regular device. .Pp If a .Dq host:port pair is given, .Nm will attempt to connect to the given .Dq host on the given .Dq port . Refer to the section on .Em PPP OVER TCP above for further details. .Pp If multiple .Dq values are specified, .Nm will attempt to open each one in turn until it succeeds or runs out of devices. .It set dial Ar chat-script This specifies the chat script that will be used to dial the other side. See also the .Dq set login command below. Refer to .Xr chat 8 and to the example configuration files for details of the chat script format. It is possible to specify some special .Sq values in your chat script as follows: .Bd -unfilled -offset indent .It Li \\\\\\\\\\\\\\\\c When used as the last character in a .Sq send string, this indicates that a newline should not be appended. .It Li \\\\\\\\\\\\\\\\d When the chat script encounters this sequence, it delays two seconds. .It Li \\\\\\\\\\\\\\\\p When the chat script encounters this sequence, it delays for one quarter of a second. .It Li \\\\\\\\\\\\\\\\n This is replaced with a newline character. .It Li \\\\\\\\\\\\\\\\r This is replaced with a carriage return character. .It Li \\\\\\\\\\\\\\\\s This is replaced with a space character. .It Li \\\\\\\\\\\\\\\\t This is replaced with a tab character. .It Li \\\\\\\\\\\\\\\\T This is replaced by the current phone number (see .Dq set phone below). .It Li \\\\\\\\\\\\\\\\P This is replaced by the current .Ar authkey value (see .Dq set authkey above). .It Li \\\\\\\\\\\\\\\\U This is replaced by the current .Ar authname value (see .Dq set authname above). .Ed .Pp Note that two parsers will examine these escape sequences, so in order to have the .Sq chat parser see the escape character, it is necessary to escape it from the .Sq command parser . This means that in practice you should use two escapes, for example: .Bd -literal -offset indent set dial "... ATDT\\\\T CONNECT" .Ed .Pp It is also possible to execute external commands from the chat script. To do this, the first character of the expect or send string is an exclamation mark .Pq Dq \&! . When the command is executed, standard input and standard output are directed to the modem device (see the .Dq set device command), and standard error is read by .Nm and substituted as the expect or send string. If .Nm is running in interactive mode, file descriptor 3 is attached to .Pa /dev/tty . .Pp For example (wrapped for readability); .Bd -literal -offset indent set login "TIMEOUT 5 \\"\\" \\"\\" login:--login: ppp \e word: ppp \\"!sh \\\\\\\\-c \\\\\\"echo \\\\\\\\-n label: >&2\\\\\\"\\" \e \\"!/bin/echo in\\" HELLO" .Ed .Pp would result in the following chat sequence (output using the .Sq set log local chat command before dialing): .Bd -literal -offset indent Dial attempt 1 of 1 dial OK! Chat: Expecting: Chat: Sending: Chat: Expecting: login:--login: Chat: Wait for (5): login: Chat: Sending: ppp Chat: Expecting: word: Chat: Wait for (5): word: Chat: Sending: ppp Chat: Expecting: !sh \\-c "echo \\-n label: >&2" Chat: Exec: sh -c "echo -n label: >&2" Chat: Wait for (5): !sh \\-c "echo \\-n label: >&2" --> label: Chat: Exec: /bin/echo in Chat: Sending: Chat: Expecting: HELLO Chat: Wait for (5): HELLO login OK! .Ed .Pp Note (again) the use of the escape character, allowing many levels of nesting. Here, there are four parsers at work. The first parses the original line, reading it as three arguments. The second parses the third argument, reading it as 11 arguments. At this point, it is important that the .Dq \&- signs are escaped, otherwise this parser will see them as constituting an expect-send-expect sequence. When the .Dq \&! character is seen, the execution parser reads the first command as three arguments, and then .Xr sh 1 itself expands the argument after the .Fl c . As we wish to send the output back to the modem, in the first example we redirect our output to file descriptor 2 (stderr) so that .Nm itself sends and logs it, and in the second example, we just output to stdout, which is attached directly to the modem. .Pp This, of course means that it is possible to execute an entirely external .Dq chat command rather than using the internal one. See .Xr chat 8 for a good alternative. .It set enddisc Op label|IP|MAC|magic|psn value This command sets our local endpoint discriminator. If set prior to LCP negotiation, .Nm will send the information to the peer using the LCP endpoint discriminator option. The following discriminators may be set: .Bd -unfilled -offset indent .It Li label The current label is used. .It Li IP Our local IP number is used. As LCP is negotiated prior to IPCP, it is possible that the IPCP layer will subsequently change this value. If it does, the endpoint discriminator stays at the old value unless manually reset. .It Li MAC This is similar to the .Ar IP option above, except that the MAC address associated with the local IP number is used. If the local IP number is not resident on any Ethernet interface, the command will fail. .Pp As the local IP number defaults to whatever the machine host name is, .Dq set enddisc mac is usually done prior to any .Dq set ifaddr commands. .It Li magic A 20 digit random number is used. .It Li psn Ar value The given .Ar value is used. .Ar Value should be set to an absolute public switched network number with the country code first. .Ed .Pp If no arguments are given, the endpoint discriminator is reset. .It set escape Ar value... This option is similar to the .Dq set accmap option above. It allows the user to specify a set of characters that will be `escaped' as they travel across the link. .It set filter dial|alive|in|out rule-no permit|deny Ar "[src_addr/width] [dst_addr/width] [proto [src [lt|eq|gt port]] [dst [lt|eq|gt port]] [estab] [syn] [finrst]]" .Nm Ppp supports four filter sets. The .Em alive filter specifies packets that keep the connection alive - reseting the idle timer. The .Em dial filter specifies packets that cause .Nm to dial when in .Fl auto mode. The .Em in filter specifies packets that are allowed to travel into the machine and the .Em out filter specifies packets that are allowed out of the machine. .Pp Filtering is done prior to any IP alterations that might be done by the alias engine. By default all filter sets allow all packets to pass. Rules are processed in order according to .Ar rule-no . Up to 20 rules may be given for each set. If a packet doesn't match any of the rules in a given set, it is discarded. In the case of .Em in and .Em out filters, this means that the packet is dropped. In the case of .Em alive filters it means that the packet will not reset the idle timer and in the case of .Em dial filters it means that the packet will not trigger a dial. A packet failing to trigger a dial will be dropped rather than queued. Refer to the section on PACKET FILTERING above for further details. .It set hangup Ar chat-script This specifies the chat script that will be used to reset the modem before it is closed. It should not normally be necessary, but can be used for devices that fail to reset themselves properly on close. .It set help|? Op Ar command This command gives a summary of available set commands, or if .Ar command is specified, the command usage is shown. .It set ifaddr Ar [myaddr [hisaddr [netmask [triggeraddr]]]] This command specifies the IP addresses that will be used during IPCP negotiation. Addresses are specified using the format .Pp .Dl a.b.c.d/n .Pp Where .Ar a.b.c.d is the preferred IP, but .Ar n specifies how many bits of the address we will insist on. If .Ar /n is omitted, it defaults to .Ar /32 unless the IP address is 0.0.0.0 in which case it defaults to .Ar /0 . .Pp .Ar Hisaddr may also be specified as a range of IP numbers in the format .Pp .Dl a.b.c.d[-d.e.f.g][,h.i.j.k[-l,m,n,o]]... .Pp for example: .Pp .Dl set ifaddr 10.0.0.1 10.0.1.2-10.0.1.10,10.0.1.20 .Pp will only negotiate .Ar 10.0.0.1 as the local IP number, but may assign any of the given 10 IP numbers to the peer. If the peer requests one of these numbers, and that number is not already in use, .Nm will grant the peers request. This is useful if the peer wants to re-establish a link using the same IP number as was previously allocated (thus maintaining any existing tcp connections). .Pp If the peer requests an IP number that's either outside of this range or is already in use, .Nm will suggest a random unused IP number from the range. .Pp If .Ar triggeraddr is specified, it is used in place of .Ar myaddr in the initial IPCP negotiation. However, only an address in the .Ar myaddr range will be accepted. This is useful when negotiating with some .Dv PPP implementations that will not assign an IP number unless their peer requests .Ar 0.0.0.0 . .Pp It should be noted that in .Fl auto mode, .Nm will configure the interface immediately upon reading the .Dq set ifaddr line in the config file. In any other mode, these values are just used for IPCP negotiations, and the interface isn't configured until the IPCP layer is up. .Pp Note that the .Ar HISADDR argument may be overridden by the third field in the .Pa ppp.secret file once the client has authenticated itself .Pq if PAP or CHAP are Dq enabled . Refer to the .Em AUTHENTICATING INCOMING CONNECTIONS section for details. .Pp In all cases, if the interface is already configured, .Nm will try to maintain the interface IP numbers so that any existing bound sockets will remain valid. .It set ccpretry Ar period .It set chapretry Ar period .It set ipcpretry Ar period .It set lcpretry Ar period .It set papretry Ar period These commands set the number of seconds that .Nm will wait before resending Finite State Machine (FSM) Request packets. The default .Ar period for all FSMs is 3 seconds (which should suffice in most cases). .It set log [local] [+|-] Ns Ar value... This command allows the adjustment of the current log level. Refer to the Logging Facility section for further details. .It set login Ar chat-script This .Ar chat-script compliments the dial-script. If both are specified, the login script will be executed after the dial script. Escape sequences available in the dial script are also available here. .It set lqrperiod Ar frequency This command sets the .Ar frequency in seconds at which .Em LQR or .Em ECHO LQR packets are sent. The default is 30 seconds. You must also use the .Dq enable lqr command if you wish to send LQR requests to the peer. .It set mode Ar interactive|auto|ddial|background This command allows you to change the .Sq mode of the specified link. This is normally only useful in multi-link mode, but may also be used in uni-link mode. .Pp It is not possible to change a link that is .Sq direct or .Sq dedicated . .It set mrru Op Ar value Setting this option enables Multi-link PPP negotiations, also known as Multi-link Protocol or MP. There is no default MRRU (Maximum Reconstructed Receive Unit) value. If no argument is given, multi-link mode is disabled. .It set mru Op Ar value The default MRU (Maximum Receive Unit) is 1500. If it is increased, the other side *may* increase its mtu. There is no point in decreasing the MRU to below the default as the .Em PPP protocol *must* be able to accept packets of at least 1500 octets. If no argument is given, 1500 is assumed. .It set mtu Op Ar value The default MTU is 1500. At negotiation time, .Nm will accept whatever MRU or MRRU that the peer wants (assuming it's not less than 296 bytes). If the MTU is set, .Nm will not accept MRU/MRRU values less than .Ar value . When negotiations are complete, the MTU is assigned to the interface, even if the peer requested a higher value MRU/MRRU. This can be useful for limiting your packet size (giving better bandwidth sharing at the expense of more header data). .Pp If no .Ar value is given, 1500, or whatever the peer asks for is used. .It set nbns Op Ar x.x.x.x Op Ar y.y.y.y This option allows the setting of the Microsoft NetBIOS name server values to be returned at the peers request. If no values are given, .Nm will reject any such requests. .It set openmode active|passive Op Ar delay By default, .Ar openmode is always .Ar active with a one second .Ar delay . That is, .Nm will always initiate LCP/IPCP/CCP negotiation one second after the line comes up. If you want to wait for the peer to initiate negotiations, you can use the value .Ar passive . If you want to initiate negotiations immediately or after more than one second, the appropriate .Ar delay may be specified here in seconds. .It set parity odd|even|none|mark This allows the line parity to be set. The default value is .Ar none . .It set phone Ar telno[|telno]...[:telno[|telno]...]... This allows the specification of the phone number to be used in place of the \\\\T string in the dial and login chat scripts. Multiple phone numbers may be given separated by a pipe (|) or a colon (:). Numbers after the pipe are only dialed if the dial or login script for the previous number failed. Numbers separated by a colon are tried sequentially, irrespective of the reason the line was dropped. If multiple numbers are given, .Nm will dial them according to these rules until a connection is made, retrying the maximum number of times specified by .Dq set redial below. In .Fl background mode, each number is attempted at most once. .It set reconnect Ar timeout ntries Should the line drop unexpectedly (due to loss of CD or LQR failure), a connection will be re-established after the given .Ar timeout . The line will be re-connected at most .Ar ntries times. .Ar Ntries defaults to zero. A value of .Ar random for .Ar timeout will result in a variable pause, somewhere between 0 and 30 seconds. .It set redial Ar seconds[.nseconds] [attempts] .Nm Ppp can be instructed to attempt to redial .Ar attempts times. If more than one phone number is specified (see .Dq set phone above), a pause of .Ar nseconds is taken before dialing each number. A pause of .Ar seconds is taken before starting at the first number again. A value of .Ar random may be used here in place of .Ar seconds and .Ar nseconds , causing a random delay of between 0 and 30 seconds. .Pp Note, this delay will be effective, even after .Ar attempts has been exceeded, so an immediate manual dial may appear to have done nothing. If an immediate dial is required, a .Dq \&! should immediately follow the .Dq open keyword. See the .Dq open description above for further details. .It set server|socket Ar TcpPort|LocalName|none password Op Ar mask This command tells .Nm to listen on the given socket or .Sq diagnostic port for incoming command connections. .Pp The word .Ar none instructs .Nm to close any existing socket. .Pp If you wish to specify a local domain socket, .Ar LocalName must be specified as an absolute file name, otherwise it is assumed to be the name or number of a TCP port. You may specify the octal umask that should be used with local domain sockets as a four character octal number beginning with .Sq 0 . Refer to .Xr umask 2 for umask details. Refer to .Xr services 5 for details of how to translate TCP port names. .Pp You must also specify the password that must be entered by the client (using the .Dq passwd command above) when connecting to this socket. If the password is specified as an empty string, no password is required for connecting clients. .Pp When specifying a local domain socket, the first .Dq %d sequence found in the socket name will be replaced with the current interface unit number. This is useful when you wish to use the same profile for more than one connection. .Pp In a similar manner TCP sockets may be prefixed with the .Dq + character, in which case the current interface unit number is added to the port number. .Pp When using .Nm with a server socket, the .Xr pppctl 8 command is the preferred mechanism of communications. Currently, .Xr telnet 1 can also be used, but link encryption may be implemented in the future, so .Xr telnet 1 should not be relied upon. .It set speed Ar value This sets the speed of the serial device. .It set stopped Ar [LCPseconds [CCPseconds]] If this option is set, .Nm will time out after the given FSM (Finite State Machine) has been in the stopped state for the given number of .Dq seconds . This option may be useful if the peer sends a terminate request, but never actually closes the connection despite our sending a terminate acknowledgement. This is also useful if you wish to .Dq set openmode passive and time out if the peer doesn't send a Configure Request within the given time. Use .Dq set log +lcp +ccp to make .Nm log the appropriate state transitions. .Pp The default value is zero, where .Nm doesn't time out in the stopped state. .Pp This value should not be set to less than the openmode delay (see .Dq set openmode above). .It set timeout Ar idleseconds This command allows the setting of the idle timer. Refer to the section titled .Dq SETTING THE IDLE TIMER for further details. .It set vj slotcomp on|off This command tells .Nm whether it should attempt to negotiate VJ slot compression. By default, slot compression is turned .Ar on . .It set vj slots Ar nslots This command sets the initial number of slots that .Nm will try to negotiate with the peer when VJ compression is enabled (see the .Sq enable command above). It defaults to a value of 16. .Ar Nslots must be between .Ar 4 and .Ar 16 inclusive. .El .Pp .It shell|! Op Ar command If .Ar command is not specified a shell is invoked according to the .Dv SHELL environment variable. Otherwise, the given .Ar command is executed. Word replacement is done in the same way as for the .Dq !bg commanad as described above. .Pp Use of the ! character requires a following space as with any of the other commands. You should note that this command is executed in the foreground - .Nm will not continue running until this process has exited. Use the .Dv bg command if you wish processing to happen in the background. .It show Ar var This command allows the user to examine the following: .Bl -tag -width XX .It show bundle Show the current bundle settings. .It show ccp Show the current CCP compression statistics. .It show compress Show the current VJ compression statistics. .It show escape Show the current escape characters. .It show filter Op Ar name List the current rules for the given filter. If .Ar name is not specified, all filters are shown. .It show hdlc Show the current HDLC statistics. .It show help|? Give a summary of available show commands. .It show ipcp Show the current IPCP statistics. .It show lcp Show the current LCP statistics. .It show [data]link Show high level link information. .It show links Show a list of available logical links. .It show log Show the current log values. .It show mem Show current memory statistics. .It show modem Show low level link information. .It show proto Show current protocol totals. .It show route Show the current routing tables. .It show stopped Show the current stopped timeouts. .It show timer Show the active alarm timers. .It show version Show the current version number of .Nm ppp . .El .Pp .It term Go into terminal mode. Characters typed at the keyboard are sent to the modem. Characters read from the modem are displayed on the screen. When a .Nm peer is detected on the other side of the modem, .Nm automatically enables Packet Mode and goes back into command mode. .El .Pp .Sh MORE DETAILS .Bl -bullet .It Read the example configuration files. They are a good source of information. .It Use .Dq help , .Dq show ? , .Dq alias ? , .Dq set ? and .Dq set ? to get online information about what's available. .It The following urls contain useful information: .Bl -bullet -compact .It http://www.FreeBSD.org/FAQ/userppp.html .It http://www.FreeBSD.org/handbook/userppp.html .El .Pp .El .Pp .Sh FILES .Nm Ppp refers to four files: .Pa ppp.conf , .Pa ppp.linkup , .Pa ppp.linkdown and .Pa ppp.secret . These files are placed in the .Pa /etc/ppp directory. .Bl -tag -width XX .It Pa /etc/ppp/ppp.conf System default configuration file. .It Pa /etc/ppp/ppp.secret An authorisation file for each system. .It Pa /etc/ppp/ppp.linkup A file to check when .Nm establishes a network level connection. .It Pa /etc/ppp/ppp.linkdown A file to check when .Nm closes a network level connection. .It Pa /var/log/ppp.log Logging and debugging information file. Note, this name is specified in .Pa /etc/syslogd.conf . See .Xr syslog.conf 5 for further details. .It Pa /var/spool/lock/LCK..* tty port locking file. Refer to .Xr uucplock 3 for further details. .It Pa /var/run/tunN.pid The process id (pid) of the .Nm program connected to the tunN device, where .Sq N is the number of the device. .It Pa /var/run/ttyXX.if The tun interface used by this port. Again, this file is only created in .Fl background , .Fl auto and .Fl ddial modes. .It Pa /etc/services Get port number if port number is using service name. .It Pa /var/run/ppp-authname-class-value In multi-link mode, local domain sockets are created using the peer authentication name .Pq Sq authname , the peer endpoint discriminator class .Pq Sq class and the peer endpoint discriminator value .Pq Sq value . As the endpoint discriminator value may be a binary value, it is turned to HEX to determine the actual file name. .Pp This socket is used to pass links between different instances of .Nm ppp . .El .Pp .Sh SEE ALSO .Xr at 1 , .Xr ftp 1 , .Xr gzip 1 , .Xr hostname 1 , .Xr login 1 , .Xr tcpdump 1 , .Xr telnet 1 , .Xr syslog 3 , .Xr uucplock 3 , .Xr crontab 5 , .Xr group 5 , .Xr passwd 5 , .Xr resolv.conf 5 , .Xr syslog.conf 5 , .Xr adduser 8 , .Xr chat 8 , .Xr getty 8 , .Xr inetd 8 , .Xr init 8 , .Xr named 8 , .Xr ping 8 , .Xr pppctl 8 , .Xr pppd 8 , .Xr route 8 , .Xr syslogd 8 , .Xr traceroute 8 , .Xr vipw 8 .Sh HISTORY This program was originally written by Toshiharu OHNO (tony-o@iij.ad.jp), and was submitted to FreeBSD-2.0.5 by Atsushi Murai (amurai@spec.co.jp). .Pp It was substantially modified during 1997 by Brian Somers (brian@Awfulhak.org), and was ported to OpenBSD in November that year (just after the 2.2 release). .Pp Most of the code was rewritten by Brian Somers in early 1998 when multi-link ppp support was added.