- Setting up a PPP link.
-
-Setting up a PPP link between two machines involves several steps:
-
-1. Prepare both of the machines which are to be connected:
- 1A. Make and install the pppd, pppstats and chat programs.
- 1B. Install the ppp driver in the kernel.
-The README.* files give details on this step.
-
-2. Decide on the IP addresses to be used and the level of
-authentication required by each machine, and set up the /etc/ppp
-directories accordingly.
-
-3. Set up the serial link between the two machines and run pppd on
-each machine. The two pppd's then negotiate and set up the link.
-
-Step 1 is described in the system-specific README.* files. The
-remaining steps are described below. Steps 1 and 2 need only be done
-once; step 3 is done each time the link is to be established.
-
-
-Choosing IP addresses.
-
-If a host is already connected to the Internet via a LAN such as
-Ethernet, then it will already have at least one IP address assigned,
-which will usually be the IP address of the LAN interface. In such
-cases, it is usually most convenient to use that address as the local
-IP address of the PPP interface(s) on that host. This is OK because
-the PPP interface(s) are point-to-point interfaces.
-
-If a host is not connected to the Internet, then an IP address needs
-to be assigned for it. If PPP is to be used to link it to another
-host which is connected to the Internet, is is usually most convenient
-to assign it an address on the same subnet as the remote host. If the
-other host is not connected to the Internet either, then the choice of
-IP addresses is quite arbitrary.
-
-Authentication.
-
-The level of authentication required depends on the situation, but
-generally hosts which are connected to the Internet via a LAN should
-be set up to (a) require the remote host to authenticate itself, and
-(b) restrict the remote host's choice of IP address, based on its
-identity. Otherwise the possibility exists for a remote host to
-impersonate another host on the local subnet. (However, when you are
-first installing PPP, it is probably easier to leave authentication
-disabled until you get to the point where you can successfully
-establish a link.)
-
-Setting up /etc/ppp.
-
-The /etc/ppp directory contains various files used by pppd; it should
-be created by the system administrator when installing PPP. It would
-typically contain the following files:
-
- chap-secrets Secrets used for authenticating with CHAP
- pap-secrets Secrets used for authenticating with PAP
- options Options that the system administrator wants to
- apply whenever pppd is run
-
-Since this directory contains files of secrets used for
-authentication, it should not be in a partition which is accessible
-from other hosts (e.g., exported by NFS).
-
-The `options' file contains any options which the system administrator
-wants pppd to use whenever it is run. If authentication is to be
-required, this should contain the `auth' and `usehostname' options.
-If the /etc/ppp/options file does not exist, or is not readable by
-pppd, it will refuse to run.
-
-Secrets for PAP (Password Authentication Protocol) authentication are
-stored in /etc/ppp/pap-secrets; secrets for CHAP (Cryptographic
-Authentication Protocol) are stored in /etc/ppp/chap-secrets. These
-files have the same format, and store secrets both for authenticating
-other hosts, and for authenticating this host to others. The format
-is that there are 3 or more words per line, which are:
-
- client - name of the machine to be authenticated
- server - name of the machine requiring the authentication
- secret - password or CHAP secret known by both client and server
- IP addresses - zero or more IP addresses which the client may
- use (this field is only used on the server).
-
-For example, if a LAN-connected host called "worksun" is to require
-authentication, and a host "bsdbox" is to connect to it and
-authenticate itself using CHAP, then both machines should have a
-/etc/ppp/chap-secrets file, which should contain a line something
-like:
-
- bsdbox worksun "an unguessable secret" bsdbox.my.domain
-
-Setting up syslog.
-
-pppd issues messages using syslog facility daemon (or local2 if it has
-been compiled with debugging enabled); chat uses facility local2. It
-is useful to see messages of priority notice or higher on the console.
-To see these, find the line in /etc/syslog.conf which has /dev/console
-on the right-hand side, and add `daemon.notice' on the left. This
-line should end up something like this:
+ Configuring a PPP link.
+
+After you have compiled and installed this package, there are some
+configuration files which will generally need to be set up. The
+pppd(8) man page is the best reference for the full details; this file
+outlines the configuration process for the most common case, where
+this package is being used to enable a machine to dial an ISP and
+connect to the internet. The FAQ and README.linux files also provide
+useful information about setting up PPP.
+
+Dialling an ISP.
+****************
+
+Usually, an ISP will assign an IP address to your machine, and will
+refuse to authenticate itself to you. Some ISPs require a username
+and password to be entered before PPP service commences, while others
+use PPP authentication (using either the PAP or CHAP protocols).
+
+The recommended way to set up to dial an ISP is for the system
+administrator to create a file under /etc/ppp/peers, named for the ISP
+that you will be dialling. For example, suppose the file is called
+/etc/ppp/peers/isp. This file would contain something like this:
+
+ttyS0 # modem is connected to /dev/ttyS0
+38400 # run the serial port at 38400 baud
+crtscts # use hardware flow control
+noauth # don't require the ISP to authenticate itself
+defaultroute # use the ISP as our default route
+connect '/usr/sbin/chat -v -f /etc/ppp/chat-isp'
+
+If there are any other pppd options that should apply when calling
+this ISP, they can also be placed in this file.
+
+The /etc/ppp/chat-isp file named in the last line contains the script
+for chat(8) to use to dial the ISP and go through any username/
+password authentication required before PPP service starts. Here is
+an example (for dialling an Annex terminal server):
+
+ABORT "NO CARRIER"
+ABORT "NO DIALTONE"
+ABORT "ERROR"
+ABORT "NO ANSWER"
+ABORT "BUSY"
+ABORT "Username/Password Incorrect"
+"" "at"
+OK "at&d2&c1"
+OK "atdt2479381"
+"name:" "^Uusername"
+"word:" "\qpassword"
+"annex" "ppp"
+"Switching to PPP-ppp-Switching to PPP"
+
+See the chat(8) man page for details of the script. If you are not
+sure how the initial dialog with your ISP will go, you could use
+a terminal emulator such as kermit or minicom to go through the
+process manually.
+
+If your ISP requires PAP or CHAP authentication, you will have to
+create a line in /etc/ppp/pap-secrets or /etc/ppp/chap-secrets like
+this:
+
+myhostname * "password"
+
+(Replace myhostname with the hostname of your machine.)
+
+At this point, you can initiate the link with the command:
+
+/usr/sbin/pppd call isp
+
+(N.B.: pppd might be installed in a different directory on some
+systems).
+
+This will return to the shell prompt immediately, as pppd will detach
+itself from its controlling terminal. (If you don't want it to do
+this, use the "nodetach" option.)
+
+Pppd will log messages describing the progress of the connection and
+any errors using the syslog facility (see the syslogd(8) and
+syslog.conf(5) man pages). Pppd issues messages using syslog facility
+daemon (or local2 if it has been compiled with debugging enabled);
+chat uses facility local2. It is often useful to see messages of
+priority notice or higher on the console. To see these, find the line
+in /etc/syslog.conf which has /dev/console on the right-hand side, and
+add `daemon.notice' on the left. This line should end up something
+like this:
*.err;kern.debug;daemon,local2,auth.notice;mail.crit /dev/console
After modifying syslog.conf, you will then need to send a HUP signal
to syslogd (or reboot).
-
-Setting up a PPP link.
-
-Establishing a PPP connection between two machines basically involves
-setting up a serial link and running pppd on both ends of the link.
-How this is done depends on the nature of the serial link, which may
-be as simple as a null modem cable between two machines, or it may
-involve modems, terminal servers, telnet sessions, etc. The `chat'
-program is very useful in setting up the serial link because it
-enables you to automate any dialog which may be required, e.g.,
-logging in to the remote machine with a username and password, issuing
-a command to start ppp on the remote machine, etc. As an example,
-the link could be started by issuing a command like
-
- pppd /dev/ttya 38400 connect 'chat -f /etc/ppp/chat-script'
-
-where the file /etc/ppp/chat-script contains
-
- "" atdt2135476
- login: myname
- Password: "\qmypassword"
- "$ " "\qpppd"
-
-The words in this script are alternately strings to look for and
-strings to send. In this example, we start by sending a dial command
-to the modem; then we look for "login:", send "myname", look for
-"Password:", send "mypassword" (the "\q" prevents chat from logging it
-when you use the -v option), look for "$ " (the end of the shell
-prompt) and send "pppd" to start up ppp on the remote machine (the
-"\q" cancels the effect of the previous "\q").
-
-In another scenario, you could establish the serial link manually,
-e.g. using Kermit to dial out, log into the remote machine, and issue
-the commands to start ppp there. Then you have to exit Kermit without
-having the modem hang up, and then start pppd locally, using a command
-like this:
-
- pppd /dev/ttya 38400
-
-When a device is given, as in this command line, pppd will put itself
-in the background. The two pppd's should then negotiate and bring up
-the link. If you have edited /etc/syslog.conf as described above, you
-will see messages from pppd giving the local and remote IP addresses
-of the link when it is successfully established.
-
-If the local machine has no other connection to the Internet, you can
-ask pppd to add a default route via the remote host by adding the
-`defaultroute' option to the pppd command.
-
-N.B. When you run pppd on the remote machine, you usually want it to
-use the tty device where you logged in. In this case, do not give a
-device name to pppd; it uses the controlling tty by default. This may
-be a pty, e.g., if the serial link contains a telnet session, except
-under Ultrix (pppd will not run on a pty under Ultrix, due to the pty
-driver not passing ioctls to the ppp line discipline code).
-
-If the remote machine is connected to the Internet via a LAN, it is
-often useful to add the `proxyarp' option. The `asyncmap' option is
-also useful if the serial line is not completely transparent;
-`asyncmap 200a0000' is appropriate if the serial link includes a
-telnet.
-
-Some people find it convenient to set up a `ppp' username on the
-remote machine, with no password, and a shell script which runs pppd
-as its login shell.
-
-Other random points about running pppd:
- - If you want the local address of the PPP link to be
- different from the (first) IP address of the host, you need
- to put the desired address on the pppd command line with a
- colon appended.
- - The performance will probably be better if you reduce the
- MRU (maximum receive unit) on both ends; 296 is a good
- value. To do this, use the option `mru 296'.
- - You DO NOT need to use ifconfig to configure the addresses
- of the ppp interface. Pppd does all the necessary work
- (assigning addresses, marking the interface up, etc.).
-
-
-Terminating the PPP link.
-
When you wish terminate the PPP link, you should send a TERM or INTR
-signal to one of the pppd's, e.g., with a command like:
-
- kill `cat /etc/ppp/ppp0.pid`
-
-on SunOS or Ultrix, or
+signal to pppd. Pppd writes its process ID to a file called
+ppp<n>.pid in /var/run (or /etc/ppp on older systems such as SunOS or
+Ultrix). Here <n> is the PPP interface unit number, which will be 0
+unless you have more than one PPP link running simultaneously. Thus
+you can terminate the link with a command like
kill `cat /var/run/ppp0.pid`
-
-on {386,Net,Free}BSD.
-
-That pppd will inform the other pppd to terminate, and they will both
-clean up and exit.
-
-If pppd is attached to a hardware serial port connected to a modem,
-then it should get a HUP signal when the modem hangs up, which will
-cause it to clean up and exit. Whether it does or not depends on the
-driver, and on Suns, on the setting of the `tty soft carrier' flag,
-which is manipulated by the /usr/etc/ttysoftcar program (see
-ttysoftcar(8)).
-
-
-Debugging.
-
-If the link comes up successfully, you should see messages logged to
-the console like "Local IP address: xx.xx.xx.xx" and "Remote IP
-address: yy.yy.yy.yy" (assuming you've edited /etc/syslog.conf as
-described above). If the link doesn't come up, it could be due to any
-of several factors:
-
-- Perhaps the serial connection is not being set up successfully, or
-you haven't succeeded in getting ppp running on the remote machine.
-You can use the -v flag to chat; it will then log the characters it
-sends and receives (using syslog with facility `local2' and level
-`debug').
-
-- Perhaps the PPP negotiation with the peer is failing. You can use
-the `debug' option to pppd; it will then log the contents of all
-control packets sent and received (using syslog with facility `daemon'
-and level `debug').
-
-In some cases, the link will come up successfully, but you may then be
-unable to use network-based applications over the link. This usually
-indicates an IP-address assignment problem or a routing problem. Or
-you may be able to communicate with the peer machine but not any
-machine beyond that. Typically this is a routing problem. For the
-common case where the local machine is only connected to the Internet
-via the peer, this problem can usually be solved if you:
- - assign the local machine an IP address on the same subnet
- as the remote machine
- - use the `defaultroute' option on the local pppd
- - use the `proxyarp' option on the remote pppd.
-
-For solving routing and network problems, the ifconfig, netstat -i,
-netstat -r, ping and traceroute commands are useful.
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