PPP and SLIP If your connection to the Internet is through a modem, or you wish to provide other people with dialup connections to the Internet using FreeBSD, you have the option of using PPP or SLIP. Furthermore, two varieties of PPP are provided: user (sometimes referred to as iijppp) and kernel. The procedures for configuring both types of PPP, and for setting up SLIP are described in this chapter. Setting up User PPP User PPP was introduced to FreeBSD in release 2.0.5 as an addition to the existing kernel implementation of PPP. So, what is different about this new PPP that warrants its addition? To quote from the manual page:
This is a user process PPP software package. Normally, PPP is implemented as a part of the kernel (e.g. as managed by pppd) and it is thus somewhat hard to debug and/or modify its behavior. However, in this implementation PPP is done as a user process with the help of the tunnel device driver (tun).
In essence, this means that rather than running a PPP daemon, the ppp program can be run as and when desired. No PPP interface needs to be compiled into the kernel, as the program can use the generic tunnel device to get data into and out of the kernel. From here on out, user ppp will be referred to simply as ppp unless a distinction needs to be made between it and any other PPP client/server software such as pppd. Unless otherwise stated, all commands in this section should be executed as root. There are a large number of enhancements in version 2 of ppp. You can discover what version you have by running ppp with no arguments and typing show version at the prompt. It is a simple matter to upgrade to the latest version of ppp (under any version of FreeBSD) by downloading the latest archive via www.Awfulhak.org. Before you start This document assumes you are in roughly this position: You have an account with an Internet Service Provider (ISP) which lets you use PPP. Further, you have a modem (or other device) connected and configured correctly which allows you to connect to your ISP. You are going to need the following information to hand: Your ISPs phone number(s). Your login name and password. This can be either a regular unix style login/password pair, or a PPP PAP or CHAP login/password pair. The IP addresses of one or more nameservers. Normally, you will be given two IP numbers. You must have this information for PPP version 1.x unless you run your own nameserver. From version 2 onwards, PPP supports nameserver address negotiation. If your ISP supports this, then using the command enable dns in your config file will tell PPP to set the nameservers for you. The following information may have been supplied by your ISP, but is not strictly necessary: The IP address of your ISP's gateway. The gateway is the machine to which you will connect and will be set up as your default route. If your ISP hasn't given you this number, we can make one up and your ISP's PPP server will tell us the correct value when we connect. This IP number is referred to as HISADDR by ppp. Your ISP's netmask. If your ISP hasn't given you this information, you can safely use a netmask of 255.255.255.0. If your ISP allocates you a static IP address and hostname then you can enter this information. Otherwise, we simply let the peer assign whatever IP number it sees fit. If you do not have any of the required information, contact your ISP and make sure they provide it to you. Building a ppp ready kernel As the description states, ppp uses the kernel tun device. It is necessary to make sure that your kernel has support for this device compiled in. To check this, go to your kernel compile directory (/sys/i386/conf or /sys/pc98/conf) and examine your kernel configuration file. It needs to have the line pseudo-device tun 1 in it somewhere. The stock GENERIC kernel has this as standard, so if you have not installed a custom kernel or you do not have a /sys directory, you do not have to change anything. If your kernel configuration file does not have this line in it, or you need to configure more than one tun device (for example, if you are setting up a server and could have 16 dialup ppp connections at any one time then you will need to use 16 instead of 1), then you should add the line, re-compile, re-install and boot the new kernel. Please refer to the Configuring the FreeBSD Kernel section for more information on kernel configuration. You can check how many tunnel devices your current kernel has by typing the following: &prompt.root; ifconfig -a tun0: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1500 inet 200.10.100.1 --> 203.10.100.24 netmask 0xffffffff tun1: flags=8050<POINTOPOINT,RUNNING,MULTICAST> mtu 576 tun2: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1500 inet 203.10.100.1 --> 203.10.100.20 netmask 0xffffffff tun3: flags=8010<POINTOPOINT,MULTICAST> mtu 1500 This case shows four tunnel devices, two of which are currently configured and being used. It should be noted that the RUNNING flag above indicates that the interface has been used at some point—it is not an error if your interface does not show up as RUNNING. If you have a kernel without the tun device, and you can not rebuild it for some reason, all is not lost. You should be able to dynamically load the code. Refer to the appropriate &man.modload.8; and &man.lkm.4; pages for further details. You may also wish to take this opportunity to configure a firewall. Details can be found in the Firewalls section. Check the tun device Most users will only require one tun device (/dev/tun0). If you have used more (i.e., a number other than 1 in the pseudo-device line in the kernel configuration file) then alter all references to tun0 below to reflect whichever device number you are using. The easiest way to make sure that the tun0 device is configured correctly is to re-make it. To do this, execute the following commands: &prompt.root; cd /dev &prompt.root; ./MAKEDEV tun0 If you require 16 tunnel devices in your kernel, you will need to create more than just tun0: &prompt.root; cd /dev &prompt.root; ./MAKEDEV tun15 Also, to confirm that the kernel is configured correctly, the following command should give the indicated output: &prompt.root; ifconfig tun0 tun0: flags=8050<POINTOPOINT,RUNNING,MULTICAST> mtu 1500 The RUNNING flag may not yet be set, in which case you will see: &prompt.root; ifconfig tun0 tun0: flags=8010<POINTOPOINT,MULTICAST> mtu 1500 Name Resolution Configuration The resolver is the part of the system that turns IP addresses into hostnames and vice versa. It can be configured to look for maps that describe IP to hostname mappings in one of two places. The first is a file called /etc/hosts (man 5 hosts). The second is the Internet Domain Name Service (DNS), a distributed data base, the discussion of which is beyond the scope of this document. This section describes briefly how to configure your resolver. The resolver is a set of system calls that do the name mappings, but you have to tell them where to find their information. You do this by first editing the file /etc/host.conf. Do not call this file /etc/hosts.conf (note the extra s) as the results can be confusing. Edit the <filename>/etc/host.conf</filename> file This file should contain the following two lines (in this order): hosts bind These instructs the resolver to first look in the file /etc/hosts, and then to consult the DNS if the name was not found. Edit the <filename>/etc/hosts</filename>(5) file This file should contain the IP addresses and names of machines on your network. At a bare minimum it should contain entries for the machine which will be running ppp. Assuming that your machine is called foo.bar.com with the IP address 10.0.0.1, /etc/hosts should contain: 127.0.0.1 localhost 10.0.0.1 foo.bar.com foo The first line defines the alias localhost as a synonym for the current machine. Regardless of your own IP address, the IP address for this line should always be 127.0.0.1. The second line maps the name foo.bar.com (and the shorthand foo) to the IP address 10.0.0.1. If your provider allocates you a static IP address and name, then use these in place of the 10.0.0.1 entry. Edit the <filename>/etc/resolv.conf</filename> file /etc/resolv.conf tells the resolver how to behave. If you are running your own DNS, you may leave this file empty. Normally, you will need to enter the following line(s): nameserver x.x.x.x nameserver y.y.y.y domain bar.com The x.x.x.x and y.y.y.y addresses are those given to you by your ISP. Add as many nameserver lines as your ISP provides. The domain line defaults to your hostname's domain, and is probably unnecessary. Refer to the resolv.conf manual page for details of other possible entries in this file. If you are running PPP version 2 or greater, the enable dns command will tell PPP to request that your ISP confirms the nameserver values. If your ISP supplies different addresses (or if there are no nameserver lines in /etc/resolv.conf), PPP will rewrite the file with the ISP-supplied values. <command>ppp</command> Configuration Both user ppp and pppd (the kernel level implementation of PPP) use configuration files located in the /etc/ppp directory. The sample configuration files provided are a good reference for user ppp, so don't delete them. Configuring ppp requires that you edit a number of files, depending on your requirements. What you put in them depends to some extent on whether your ISP allocates IP addresses statically (i.e., you get given one IP address, and always use that one) or dynamically (i.e., your IP address can be different for each PPP session). PPP and Static IP addresses You will need to create a configuration file called /etc/ppp/ppp.conf. It should look similar to the example below. Lines that end in a : start in the first column, all other lines should be indented as shown using spaces or tabs. 1 default: 2 set device /dev/cuaa0 3 set speed 115200 4 set dial "ABORT BUSY ABORT NO\\sCARRIER TIMEOUT 5 \"\" ATE1Q0 OK-AT-OK \\dATDT\\TTIMEOUT 40 CONNECT" 5 provider: 6 set phone "(0123) 456 7890" 7 set login "TIMEOUT 10 \"\" \"\" gin:--gin: foo word: bar col: ppp" 8 set timeout 300 9 set ifaddr x.x.x.x y.y.y.y 255.255.255.0 0.0.0.0 10 add default HISADDR 11 enable dns Do not include the line numbers, they are just for reference in this discussion. Line 1: Identifies the default entry. Commands in this entry are executed automatically when ppp is run. Line 2: Identifies the device to which the modem is connected. COM1: is /dev/cuaa0 and COM2: is /dev/cuaa1. Line 3: Sets the speed you want to connect at. If 115200 doesn't work (it should with any reasonably new modem), try 38400 instead. Line 4: The dial string. User PPP uses an expect-send syntax similar to the &man.chat.8; program. Refer to the manual page for information on the features of this language. Line 5: Identifies an entry for a provider called “provider”. Line 6: Sets the phone number for this provider. Multiple phone numbers may be specified using the : or | character as a separator. The difference between these separators is described in &man.ppp.8;. To summarize, if you want to rotate through the numbers, use the :. If you want to always attempt to dial the first number first and only use the other numbers if the first number fails, use the |. Always quote the entire set of phone numbers as shown. Line 7: The login string is of the same chat-like syntax as the dial string. In this example, the string works for a service whose login session looks like this: J. Random Provider login: foo password: bar protocol: ppp You will need to alter this script to suit your own needs. When you write this script for the first time, you should enable “chat” logging to ensure that the conversation is going as expected. If you're using PAP or CHAP, there will be no login at this point, so your login string can be left blank. See PAP and CHAP authentication for further details. Line 8: Sets the default timeout (in seconds) for the connection. Here, the connection will be closed automatically after 300 seconds of inactivity. If you never want to timeout, set this value to zero. Line 9: Sets the interface addresses. The string x.x.x.x should be replaced by the IP address that your provider has allocated to you. The string y.y.y.y should be replaced by the IP address that your ISP indicated for their gateway (the machine to which you connect). If your ISP hasn't given you a gateway address, use 10.0.0.2/0. If you need to use a “guessed” address, make sure that you create an entry in /etc/ppp/ppp.linkup as per the instructions for PPP and Dynamic IP addresses. If this line is omitted, ppp cannot run in or mode. Line 10: Adds a default route to your ISPs gateway. The special word HISADDR is replaced with the gateway address specified on line 9. It is important that this line appears after line 9, otherwise HISADDR will not yet be initialized. Line 11: This line tells PPP to ask your ISP to confirm that your nameserver addresses are correct. If your ISP supports this facility, PPP can then update /etc/resolv.conf with the correct nameserver entries. It is not necessary to add an entry to ppp.linkup when you have a static IP address as your routing table entries are already correct before you connect. You may however wish to create an entry to invoke programs after connection. This is explained later with the sendmail example. Example configuration files can be found in the /etc/ppp directory. PPP and Dynamic IP addresses If your service provider does not assign static IP numbers, ppp can be configured to negotiate the local and remote addresses. This is done by “guessing” an IP number and allowing ppp to set it up correctly using the IP Configuration Protocol (IPCP) after connecting. The ppp.conf configuration is the same as PPP and Static IP addresses, with the following change: 9 set ifaddr 10.0.0.1/0 10.0.0.2/0 255.255.255.0 Again, do not include the line numbers, they are just for reference in this discussion. Indentation of at least one space is required. Line 9: The number after the / character is the number of bits of the address that ppp will insist on. You may wish to use IP numbers more appropriate to your circumstances, but the above example will always work. The last argument (0.0.0.0) tells PPP to negotiate using address 0.0.0.0 rather than 10.0.0.1. Do not use 0.0.0.0 as the first argument to set ifaddr as it prevents PPP from setting up an intial route in mode. If you are running version 1.x of PPP, uou will also need to create an entry in /etc/ppp/ppp.linkup. ppp.linkup is used after a connection has been established. At this point, ppp will know what IP addresses should really be used. The following entry will delete the existing bogus routes, and create correct ones: 1 provider: 2 delete ALL 3 add 0 0 HISADDR Line 1: On establishing a connection, ppp will look for an entry in ppp.linkup according to the following rules: First, try to match the same label as we used in ppp.conf. If that fails, look for an entry for the IP number of our gateway. This entry is a four-octet IP style label. If we still haven't found an entry, look for the MYADDR entry. Line 2: This line tells ppp to delete all existing routes for the acquired tun interface (except the direct route entry). Line 3: This line tells ppp to add a default route that points to HISADDR. HISADDR will be replaced with the IP number of the gateway as negotiated in the IPCP. See the pmdemand entry in the files /etc/ppp/ppp.conf.sample and /etc/ppp/ppp.linkup.sample for a detailed example. Version 2 of PPP introduces “sticky routes”. Any add or delete lines that contain MYADDR or HISADDR will be remembered, and any time the actual values of MYADDR or HISADDR change, the routes will be re-applied. This removes the necessity of repeating these lines in ppp.linkup. Receiving incoming calls with <command>ppp</command> This section describes setting up ppp in a server role. When you configure ppp to receive incoming calls on a machine connected to a LAN, you must decide if you wish to forward packets to the LAN. If you do, you should allocate the peer an IP number from your LAN's subet, and use the command enable proxy in your ppp.conf file. You should also confirm that the /etc/rc.conf file (this file used to be called /etc/sysconfig) contains the following: gateway=YES Which getty? Configuring FreeBSD for Dialup Services provides a good description on enabling dialup services using getty. An alternative to getty is mgetty, a smarter version of getty designed with dialup lines in mind. The advantages of using mgetty is that it actively talks to modems, meaning if port is turned off in /etc/ttys then your modem won't answer the phone. Later versions of mgetty (from 0.99beta onwards) also support the automatic detection of PPP streams, allowing your clients script-less access to your server. Refer to Mgetty and AutoPPP for more information on mgetty. PPP permissions ppp must normally be run as user id 0. If however you wish to allow ppp to run in server mode as a normal user by executing ppp as described below, that user must be given permission to run ppp by adding them to the network group in /etc/group. You will also need to give them access to one or more sections of the configuration file using the allow command: allow users fred mary If this command is used in the default section, it gives the specified users access to everything. Setting up a PPP shell for dynamic-IP users Create a file called /etc/ppp/ppp-shell containing the following: #!/bin/sh IDENT=`echo $0 | sed -e 's/^.*-\(.*\)$/\1/'` CALLEDAS="$IDENT" TTY=`tty` if [ x$IDENT = xdialup ]; then IDENT=`basename $TTY` fi echo "PPP for $CALLEDAS on $TTY" echo "Starting PPP for $IDENT" exec /usr/sbin/ppp -direct $IDENT This script should be executable. Now make a symbolic link called ppp-dialup to this script using the following commands: &prompt.root; ln -s ppp-shell /etc/ppp/ppp-dialup You should use this script as the shell for all your dialup ppp users. This is an example from /etc/password for a dialup PPP user with username pchilds. (remember don't directly edit the password file, use vipw) pchilds:*:1011:300:Peter Childs PPP:/home/ppp:/etc/ppp/ppp-dialup Create a /home/ppp directory that is world readable containing the following 0 byte files -r--r--r-- 1 root wheel 0 May 27 02:23 .hushlogin -r--r--r-- 1 root wheel 0 May 27 02:22 .rhosts which prevents /etc/motd from being displayed. Setting up a PPP shell for static-IP users Create the ppp-shell file as above and for each account with statically assigned IPs create a symbolic link to ppp-shell. For example, if you have three dialup customers fred, sam, and mary, that you route class C networks for, you would type the following: &prompt.root; ln -s /etc/ppp/ppp-shell /etc/ppp/ppp-fred &prompt.root; ln -s /etc/ppp/ppp-shell /etc/ppp/ppp-sam &prompt.root; ln -s /etc/ppp/ppp-shell /etc/ppp/ppp-mary Each of these users dialup accounts should have their shell set to the symbolic link created above. (ie. mary's shell should be /etc/ppp/ppp-mary). Setting up ppp.conf for dynamic-IP users The /etc/ppp/ppp.conf file should contain something along the lines of default: set debug phase lcp chat set timeout 0 ttyd0: set ifaddr 203.14.100.1 203.14.100.20 255.255.255.255 enable proxy ttyd1: set ifaddr 203.14.100.1 203.14.100.21 255.255.255.255 enable proxy The indenting is important. The default: section is loaded for each session. For each dialup line enabled in /etc/ttys create an entry similar to the one for ttyd0: above. Each line should get a unique IP address from your pool of IP addresses for dynamic users. Setting up <filename>ppp.conf</filename> for static-IP users Along with the contents of the sample /etc/ppp/ppp.conf above you should add a section for each of the statically assigned dialup users. We will continue with our fred, sam, and mary example. fred: set ifaddr 203.14.100.1 203.14.101.1 255.255.255.255 sam: set ifaddr 203.14.100.1 203.14.102.1 255.255.255.255 mary: set ifaddr 203.14.100.1 203.14.103.1 255.255.255.255 The file /etc/ppp/ppp.linkup should also contain routing information for each static IP user if required. The line below would add a route for the 203.14.101.0 class C via the client's ppp link. fred: add 203.14.101.0 netmask 255.255.255.0 HISADDR sam: add 203.14.102.0 netmask 255.255.255.0 HISADDR mary: add 203.14.103.0 netmask 255.255.255.0 HISADDR More on <command>mgetty</command>, AutoPPP, and MS extensions <command>mgetty</command> and AutoPPP Configuring and compiling mgetty with the AUTO_PPP option enabled allows mgetty to detect the LCP phase of PPP connections and automatically spawn off a ppp shell. However, since the default login/password sequence does not occur it is necessary to authenticate users using either PAP or CHAP. This section assumes the user has successfully configured, compiled, and installed a version of mgetty with the AUTO_PPP option (v0.99beta or later) Make sure your /usr/local/etc/mgetty+sendfax/login.config file has the following in it: /AutoPPP/ - - /etc/ppp/ppp-pap-dialup This will tell mgetty to run the ppp-pap-dialup script for detected PPP connections. Create a file called /etc/ppp/ppp-pap-dialup containing the following (the file should be executable): #!/bin/sh exec /usr/sbin/ppp -direct pap$IDENT For each dialup line enabled in /etc/ttys create a corresponding entry in /etc/ppp/ppp.conf. This will happily co-exist with the definitions we created above. pap: enable pap set ifaddr 203.14.100.1 203.14.100.20-203.14.100.40 enable proxy Each user logging in with this method will need to have a username/password in /etc/ppp/ppp.secret file, or alternatively add the enable passwdauth option to authenticate users via pap from the /etc/password file. If you wish to assign some users a static IP number, you can specify the number as the third argument in /etc/ppp/ppp.secret. See /etc/ppp/ppp.secret.sample for examples. MS extentions It is possible to configure PPP to supply DNS and NetBIOS nameserver addresses on demand. To enable these extensions with PPP version 1.x, the following lines might be added to the relevant section of /etc/ppp/ppp.conf. enable msext set ns 203.14.100.1 203.14.100.2 set nbns 203.14.100.5 And for PPP version 2 and above: accept dns set dns 203.14.100.1 203.14.100.2 set nbns 203.14.100.5 This will tell the clients the primary and secondary name server addresses, and a netbios nameserver host. In version 2 and above, if the set dns line is ommitted, PPP will use the values found in /etc/resolv.conf. PAP and CHAP authentication Some ISPs set their system up so that the authentication part of your connection is done using either of the PAP or CHAP authentication mechanisms. If this is the case, your ISP will not give a login: prompt when you connect, but will start talking PPP immediately. PAP is less secure than CHAP, but security is not normally an issue here as passwords, although being sent as plain text with PAP, are being transmitted down a serial line only. There's not much room for crackers to “eavesdrop”. Referring back to the PPP and Static IP addresses or PPP and Dynamic IP addresses sections, the following alterations must be made: 7 set login … 12 set authname MyUserName 13 set authkey MyPassword As always, do not include the line numbers, they are just for reference in this discussion. Indentation of at least one space is required. Line 7: Your ISP will not normally require that you log into the server if you're using PAP or CHAP. You must therefore disable your "set login" string. Line 12: This line specifies your PAP/CHAP user name. You will need to insert the correct value for MyUserName. Line 13: This line specifies your PAP/CHAP password. You will need to insert the correct value for MyPassword. You may want to add an additional line 15 accept PAP or 15 accept CHAP to make it obvious that this is the intention, but PAP and CHAP are both accepted by default. Changing your <command>ppp</command> configuration on the fly It is possible to talk to the ppp program while it is running in the background, but only if a suitable diagnostic port has been set up. To do this, add the following line to your configuration: set server /var/run/ppp-tun%d DiagnosticPassword 0177 This will tell PPP to listen to the specified unix-domain socket, asking clients for the specified password before allowing access. The %d in the name is replaced with the tun device number that is in use. Once a socket has been set up, the &man.pppctl.8; program may be used in scripts that wish to manipulate the running program. Final system configuration You now have ppp configured, but there are a few more things to do before it is ready to work. They all involve editing the /etc/rc.conf file (was /etc/sysconfig). Working from the top down in this file, make sure the hostname= line is set, e.g.: hostname=foo.bar.com If your ISP has supplied you with a static IP address and name, it's probably best that you use this name as your host name. Look for the network_interfaces variable. If you want to configure your system to dial your ISP on demand, make sure the tun0 device is added to the list, otherwise remove it. network_interfaces="lo0 tun0" ifconfig_tun0= The ifconfig_tun0 variable should be empty, and a file called /etc/start_if.tun0 should be created. This file should contain the line ppp -auto mysystem This script is executed at network configuration time, starting your ppp daemon in automatic mode. If you have a LAN for which this machine is a gateway, you may also wish to use the switch. Refer to the manual page for further details. Set the router program to NO with the line router_enable=NO (/etc/rc.conf) router=NO (/etc/sysconfig) It is important that the routed daemon is not started (it's started by default) as routed tends to delete the default routing table entries created by ppp. It is probably worth your while ensuring that the sendmail_flags line does not include the option, otherwise sendmail will attempt to do a network lookup every now and then, possibly causing your machine to dial out. You may try: sendmail_flags="-bd" The upshot of this is that you must force sendmail to re-examine the mail queue whenever the ppp link is up by typing: &prompt.root; /usr/sbin/sendmail -q You may wish to use the !bg command in ppp.linkup to do this automatically: 1 provider: 2 delete ALL 3 add 0 0 HISADDR 4 !bg sendmail -bd -q30m If you don't like this, it is possible to set up a “dfilter” to block SMTP traffic. Refer to the sample files for further details. All that is left is to reboot the machine. After rebooting, you can now either type &prompt.root; ppp and then dial provider to start the PPP session, or, if you want ppp to establish sessions automatically when there is outbound traffic (and you haven't created the start_if.tun0 script), type &prompt.root; ppp -auto provider Summary To recap, the following steps are necessary when setting up ppp for the first time: Client side: Ensure that the tun device is built into your kernel. Ensure that the tunX device file is available in the /dev directory. Create an entry in /etc/ppp/ppp.conf. The pmdemand example should suffice for most ISPs. If you have a dynamic IP address, create an entry in /etc/ppp/ppp.linkup. Update your /etc/rc.conf (or sysconfig) file. Create a start_if.tun0 script if you require demand dialing. Server side: Ensure that the tun device is built into your kernel. Ensure that the tunX device file is available in the /dev directory. Create an entry in /etc/passwd (using the &man.vipw.8; program). Create a profile in this users home directory that runs ppp -direct direct-server or similar. Create an entry in /etc/ppp/ppp.conf. The direct-server example should suffice. Create an entry in /etc/ppp/ppp.linkup. Update your /etc/rc.conf (or sysconfig) file. Acknowledgments This section of the handbook was last updated on Monday Aug 10, 1998 by &a.brian; Thanks to the following for their input, comments & suggestions: &a.nik; &a.dirkvangulik; &a.pjc; Setting up Kernel PPP Contributed by &a.gena;. Before you start setting up PPP on your machine make sure that pppd is located in /usr/sbin and directory /etc/ppp exists. pppd can work in two modes: as a “client”, i.e. you want to connect your machine to outside world via PPP serial connection or modem line. as a “server”, i.e. your machine is located on the network and used to connect other computers using PPP. In both cases you will need to set up an options file (/etc/ppp/options or ~/.ppprc if you have more then one user on your machine that uses PPP). You also will need some modem/serial software (preferably kermit) so you can dial and establish connection with remote host. Working as a PPP client I used the following /etc/ppp/options to connect to CISCO terminal server PPP line. crtscts # enable hardware flow control modem # modem control line noipdefault # remote PPP server must supply your IP address. # if the remote host doesn't send your IP during IPCP # negotiation , remove this option passive # wait for LCP packets domain ppp.foo.com # put your domain name here :<remote_ip> # put the IP of remote PPP host here # it will be used to route packets via PPP link # if you didn't specified the noipdefault option # change this line to <local_ip>:<remote_ip> defaultroute # put this if you want that PPP server will be your # default router To connect: Dial to the remote host using kermit (or other modem program) enter your user name and password (or whatever is needed to enable PPP on the remote host) Exit kermit (without hanging up the line). enter: &prompt.root; /usr/src/usr.sbin/pppd.new/pppd /dev/tty01 19200 Use the appropriate speed and device name. Now your computer is connected with PPP. If the connection fails for some reasons you can add the option to the /etc/ppp/options file and check messages on the console to track the problem Following /etc/ppp/pppup script will make all 3 stages automatically: #!/bin/sh ps ax |grep pppd |grep -v grep pid=`ps ax |grep pppd |grep -v grep|awk '{print $1;}'` if [ "X${pid}" != "X" ] ; then echo 'killing pppd, PID=' ${pid} kill ${pid} fi ps ax |grep kermit |grep -v grep pid=`ps ax |grep kermit |grep -v grep|awk '{print $1;}'` if [ "X${pid}" != "X" ] ; then echo 'killing kermit, PID=' ${pid} kill -9 ${pid} fi ifconfig ppp0 down ifconfig ppp0 delete kermit -y /etc/ppp/kermit.dial pppd /dev/tty01 19200 /etc/ppp/kermit.dial is kermit script that dials and makes all necessary authorization on the remote host. (Example of such script is attached to the end of this document) Use the following /etc/ppp/pppdown script to disconnect the PPP line: #!/bin/sh pid=`ps ax |grep pppd |grep -v grep|awk '{print $1;}'` if [ X${pid} != "X" ] ; then echo 'killing pppd, PID=' ${pid} kill -TERM ${pid} fi ps ax |grep kermit |grep -v grep pid=`ps ax |grep kermit |grep -v grep|awk '{print $1;}'` if [ "X${pid}" != "X" ] ; then echo 'killing kermit, PID=' ${pid} kill -9 ${pid} fi /sbin/ifconfig ppp0 down /sbin/ifconfig ppp0 delete kermit -y /etc/ppp/kermit.hup /etc/ppp/ppptest Check if PPP is still running (/usr/etc/ppp/ppptest): #!/bin/sh pid=`ps ax| grep pppd |grep -v grep|awk '{print $1;}'` if [ X${pid} != "X" ] ; then echo 'pppd running: PID=' ${pid-NONE} else echo 'No pppd running.' fi set -x netstat -n -I ppp0 ifconfig ppp0 Hangs up modem line (/etc/ppp/kermit.hup): set line /dev/tty01 ; put your modem device here set speed 19200 set file type binary set file names literal set win 8 set rec pack 1024 set send pack 1024 set block 3 set term bytesize 8 set command bytesize 8 set flow none pau 1 out +++ inp 5 OK out ATH0\13 echo \13 exit Here is an alternate method using chat instead of kermit. Contributed by &a.rhuff;. The following two files are sufficient to accomplish a pppd connection. /etc/ppp/options: /dev/cuaa1 115200 crtscts # enable hardware flow control modem # modem control line connect "/usr/bin/chat -f /etc/ppp/login.chat.script" noipdefault # remote PPP serve must supply your IP address. # if the remote host doesn't send your IP during # IPCP negotiation, remove this option passive # wait for LCP packets domain <your.domain> # put your domain name here : # put the IP of remote PPP host here # it will be used to route packets via PPP link # if you didn't specified the noipdefault option # change this line to <local_ip>:<remote_ip> defaultroute # put this if you want that PPP server will be # your default router /etc/ppp/login.chat.script: (This should actually go into a single line.) ABORT BUSY ABORT 'NO CARRIER' "" AT OK ATDT<phone.number> CONNECT "" TIMEOUT 10 ogin:-\\r-ogin: <login-id> TIMEOUT 5 sword: <password> Once these are installed and modified correctly, all you need to do is &prompt.root; pppd This sample based primarily on information provided by: Trev Roydhouse <Trev.Roydhouse@f401.n711.z3.fidonet.org> and used by permission. Working as a PPP server /etc/ppp/options: crtscts # Hardware flow control netmask 255.255.255.0 # netmask ( not required ) 192.114.208.20:192.114.208.165 # ip's of local and remote hosts # local ip must be different from one # you assigned to the ethernet ( or other ) # interface on your machine. # remote IP is ip address that will be # assigned to the remote machine domain ppp.foo.com # your domain passive # wait for LCP modem # modem line Following /etc/ppp/pppserv script will enable ppp server on your machine: #!/bin/sh ps ax |grep pppd |grep -v grep pid=`ps ax |grep pppd |grep -v grep|awk '{print $1;}'` if [ "X${pid}" != "X" ] ; then echo 'killing pppd, PID=' ${pid} kill ${pid} fi ps ax |grep kermit |grep -v grep pid=`ps ax |grep kermit |grep -v grep|awk '{print $1;}'` if [ "X${pid}" != "X" ] ; then echo 'killing kermit, PID=' ${pid} kill -9 ${pid} fi # reset ppp interface ifconfig ppp0 down ifconfig ppp0 delete # enable autoanswer mode kermit -y /etc/ppp/kermit.ans # run ppp pppd /dev/tty01 19200 Use this /etc/ppp/pppservdown script to stop ppp server: #!/bin/sh ps ax |grep pppd |grep -v grep pid=`ps ax |grep pppd |grep -v grep|awk '{print $1;}'` if [ "X${pid}" != "X" ] ; then echo 'killing pppd, PID=' ${pid} kill ${pid} fi ps ax |grep kermit |grep -v grep pid=`ps ax |grep kermit |grep -v grep|awk '{print $1;}'` if [ "X${pid}" != "X" ] ; then echo 'killing kermit, PID=' ${pid} kill -9 ${pid} fi ifconfig ppp0 down ifconfig ppp0 delete kermit -y /etc/ppp/kermit.noans Following kermit script will enable/disable autoanswer mode on your modem (/etc/ppp/kermit.ans): set line /dev/tty01 set speed 19200 set file type binary set file names literal set win 8 set rec pack 1024 set send pack 1024 set block 3 set term bytesize 8 set command bytesize 8 set flow none pau 1 out +++ inp 5 OK out ATH0\13 inp 5 OK echo \13 out ATS0=1\13 ; change this to out ATS0=0\13 if you want to disable ; autoanswer mod inp 5 OK echo \13 exit This /etc/ppp/kermit.dial script is used for dialing and authorizing on remote host. You will need to customize it for your needs. Put your login and password in this script, also you will need to change input statement depending on responses from your modem and remote host. ; ; put the com line attached to the modem here: ; set line /dev/tty01 ; ; put the modem speed here: ; set speed 19200 set file type binary ; full 8 bit file xfer set file names literal set win 8 set rec pack 1024 set send pack 1024 set block 3 set term bytesize 8 set command bytesize 8 set flow none set modem hayes set dial hangup off set carrier auto ; Then SET CARRIER if necessary, set dial display on ; Then SET DIAL if necessary, set input echo on set input timeout proceed set input case ignore def \%x 0 ; login prompt counter goto slhup :slcmd ; put the modem in command mode echo Put the modem in command mode. clear ; Clear unread characters from input buffer pause 1 output +++ ; hayes escape sequence input 1 OK\13\10 ; wait for OK if success goto slhup output \13 pause 1 output at\13 input 1 OK\13\10 if fail goto slcmd ; if modem doesn't answer OK, try again :slhup ; hang up the phone clear ; Clear unread characters from input buffer pause 1 echo Hanging up the phone. output ath0\13 ; hayes command for on hook input 2 OK\13\10 if fail goto slcmd ; if no OK answer, put modem in command mode :sldial ; dial the number pause 1 echo Dialing. output atdt9,550311\13\10 ; put phone number here assign \%x 0 ; zero the time counter :look clear ; Clear unread characters from input buffer increment \%x ; Count the seconds input 1 {CONNECT } if success goto sllogin reinput 1 {NO CARRIER\13\10} if success goto sldial reinput 1 {NO DIALTONE\13\10} if success goto slnodial reinput 1 {\255} if success goto slhup reinput 1 {\127} if success goto slhup if < \%x 60 goto look else goto slhup :sllogin ; login assign \%x 0 ; zero the time counter pause 1 echo Looking for login prompt. :slloop increment \%x ; Count the seconds clear ; Clear unread characters from input buffer output \13 ; ; put your expected login prompt here: ; input 1 {Username: } if success goto sluid reinput 1 {\255} if success goto slhup reinput 1 {\127} if success goto slhup if < \%x 10 goto slloop ; try 10 times to get a login prompt else goto slhup ; hang up and start again if 10 failures :sluid ; ; put your userid here: ; output ppp-login\13 input 1 {Password: } ; ; put your password here: ; output ppp-password\13 input 1 {Entering SLIP mode.} echo quit :slnodial echo \7No dialtone. Check the telephone line!\7 exit 1 ; local variables: ; mode: csh ; comment-start: "; " ; comment-start-skip: "; " ; end: Setting up a SLIP Client Contributed by &a.asami; 8 Aug 1995. The following is one way to set up a FreeBSD machine for SLIP on a static host network. For dynamic hostname assignments (i.e., your address changes each time you dial up), you probably need to do something much fancier. First, determine which serial port your modem is connected to. I have a symbolic link to /dev/modem from /dev/cuaa1, and only use the modem name in my configuration files. It can become quite cumbersome when you need to fix a bunch of files in /etc and .kermrc's all over the system! /dev/cuaa0 is COM1, cuaa1 is COM2, etc. Make sure you have pseudo-device sl 1 in your kernel's config file. It is included in the GENERIC kernel, so this will not be a problem unless you deleted it. Things you have to do only once Add your home machine, the gateway and nameservers to your /etc/hosts file. Mine looks like this: 127.0.0.1 localhost loghost 136.152.64.181 silvia.HIP.Berkeley.EDU silvia.HIP silvia 136.152.64.1 inr-3.Berkeley.EDU inr-3 slip-gateway 128.32.136.9 ns1.Berkeley.edu ns1 128.32.136.12 ns2.Berkeley.edu ns2 By the way, silvia is the name of the car that I had when I was back in Japan (it is called 2?0SX here in U.S.). Make sure you have before in your /etc/host.conf. Otherwise, funny things may happen. Edit the file /etc/rc.conf. Note that you should edit the file /etc/sysconfig instead if you are running FreeBSD previous to version 2.2.2. Set your hostname by editing the line that says: hostname=myname.my.domain You should give it your full Internet hostname. Add sl0 to the list of network interfaces by changing the line that says: network_interfaces="lo0" to: network_interfaces="lo0 sl0" Set the startup flags of sl0 by adding a line: ifconfig_sl0="inet ${hostname} slip-gateway netmask 0xffffff00 up" Designate the default router by changing the line: defaultrouter=NO to: defaultrouter=slip-gateway Make a file /etc/resolv.conf which contains: domain HIP.Berkeley.EDU nameserver 128.32.136.9 nameserver 128.32.136.12 As you can see, these set up the nameserver hosts. Of course, the actual domain names and addresses depend on your environment. Set the password for root and toor (and any other accounts that does not have a password). Use passwd, do not edit the /etc/passwd or /etc/master.passwd files! Reboot your machine and make sure it comes up with the correct hostname. Making a SLIP connection Dial up, type slip at the prompt, enter your machine name and password. The things you need to enter depends on your environment. I use kermit, with a script like this: # kermit setup set modem hayes set line /dev/modem set speed 115200 set parity none set flow rts/cts set terminal bytesize 8 set file type binary # The next macro will dial up and login define slip dial 643-9600, input 10 =>, if failure stop, - output slip\x0d, input 10 Username:, if failure stop, - output silvia\x0d, input 10 Password:, if failure stop, - output ***\x0d, echo \x0aCONNECTED\x0a (of course, you have to change the hostname and password to fit yours). Then you can just type slip from the kermit prompt to get connected. Leaving your password in plain text anywhere in the filesystem is generally a BAD idea. Do it at your own risk. I am just too lazy. Leave the kermit there (you can suspend it by z) and as root, type: &prompt.root; slattach -h -c -s 115200 /dev/modem If you are able to ping hosts on the other side of the router, you are connected! If it does not work, you might want to try instead of as an argument to slattach. How to shutdown the connection Type &prompt.root; kill -INT `cat /var/run/slattach.modem.pid` (as root) to kill slattach. Then go back to kermit (fg if you suspended it) and exit from it (q). The slattach man page says you have to use ifconfig sl0 down to mark the interface down, but this does not seem to make any difference for me. (ifconfig sl0 reports the same thing.) Some times, your modem might refuse to drop the carrier (mine often does). In that case, simply start kermit and quit it again. It usually goes out on the second try. Troubleshooting If it does not work, feel free to ask me. The things that people tripped over so far: Not using or in slattach (I have no idea why this can be fatal, but adding this flag solved the problem for at least one person) Using instead of (might be hard to see the difference on some fonts). Try ifconfig sl0 to see your interface status. I get: &prompt.root; ifconfig sl0 sl0: flags=10<POINTOPOINT> inet 136.152.64.181 --> 136.152.64.1 netmask ffffff00 Also, netstat -r will give the routing table, in case you get the "no route to host" messages from ping. Mine looks like: &prompt.root; netstat -r Routing tables Destination Gateway Flags Refs Use IfaceMTU Rtt Netmasks: (root node) (root node) Route Tree for Protocol Family inet: (root node) => default inr-3.Berkeley.EDU UG 8 224515 sl0 - - localhost.Berkel localhost.Berkeley UH 5 42127 lo0 - 0.438 inr-3.Berkeley.E silvia.HIP.Berkele UH 1 0 sl0 - - silvia.HIP.Berke localhost.Berkeley UGH 34 47641234 lo0 - 0.438 (root node) (this is after transferring a bunch of files, your numbers should be smaller). Setting up a SLIP Server Contributed by &a.ghelmer;. v1.0, 15 May 1995. This document provides suggestions for setting up SLIP Server services on a FreeBSD system, which typically means configuring your system to automatically startup connections upon login for remote SLIP clients. The author has written this document based on his experience; however, as your system and needs may be different, this document may not answer all of your questions, and the author cannot be responsible if you damage your system or lose data due to attempting to follow the suggestions here. This guide was originally written for SLIP Server services on a FreeBSD 1.x system. It has been modified to reflect changes in the pathnames and the removal of the SLIP interface compression flags in early versions of FreeBSD 2.X, which appear to be the only major changes between FreeBSD versions. If you do encounter mistakes in this document, please email the author with enough information to help correct the problem. Prerequisites This document is very technical in nature, so background knowledge is required. It is assumed that you are familiar with the TCP/IP network protocol, and in particular, network and node addressing, network address masks, subnetting, routing, and routing protocols, such as RIP. Configuring SLIP services on a dial-up server requires a knowledge of these concepts, and if you are not familiar with them, please read a copy of either Craig Hunt's TCP/IP Network Administration published by O'Reilly & Associates, Inc. (ISBN Number 0-937175-82-X), or Douglas Comer's books on the TCP/IP protocol. It is further assumed that you have already setup your modem(s) and configured the appropriate system files to allow logins through your modems. If you have not prepared your system for this yet, please see the tutorial for configuring dialup services; if you have a World-Wide Web browser available, browse the list of tutorials at http://www.FreeBSD.org/; otherwise, check the place where you found this document for a document named dialup.txt or something similar. You may also want to check the manual pages for &man.sio.4; for information on the serial port device driver and &man.ttys.5;, &man.gettytab.5;, &man.getty.8;, & &man.init.8; for information relevant to configuring the system to accept logins on modems, and perhaps &man.stty.1; for information on setting serial port parameters (such as clocal for directly-connected serial interfaces). Quick Overview In its typical configuration, using FreeBSD as a SLIP server works as follows: a SLIP user dials up your FreeBSD SLIP Server system and logs in with a special SLIP login ID that uses /usr/sbin/sliplogin as the special user's shell. The sliplogin program browses the file /etc/sliphome/slip.hosts to find a matching line for the special user, and if it finds a match, connects the serial line to an available SLIP interface and then runs the shell script /etc/sliphome/slip.login to configure the SLIP interface. An Example of a SLIP Server Login For example, if a SLIP user ID were Shelmerg, Shelmerg's entry in /etc/master.passwd would look something like this (except it would be all on one line): Shelmerg:password:1964:89::0:0:Guy Helmer - SLIP:/usr/users/Shelmerg:/usr/sbin/sliplogin When Shelmerg logs in, sliplogin will search /etc/sliphome/slip.hosts for a line that had a matching user ID; for example, there may be a line in /etc/sliphome/slip.hosts that reads: Shelmerg dc-slip sl-helmer 0xfffffc00 autocomp sliplogin will find that matching line, hook the serial line into the next available SLIP interface, and then execute /etc/sliphome/slip.login like this: /etc/sliphome/slip.login 0 19200 Shelmerg dc-slip sl-helmer 0xfffffc00 autocomp If all goes well, /etc/sliphome/slip.login will issue an ifconfig for the SLIP interface to which sliplogin attached itself (slip interface 0, in the above example, which was the first parameter in the list given to slip.login) to set the local IP address (dc-slip), remote IP address (sl-helmer), network mask for the SLIP interface (0xfffffc00), and any additional flags (autocomp). If something goes wrong, sliplogin usually logs good informational messages via the daemon syslog facility, which usually goes into /var/log/messages (see the manual pages for &man.syslogd.8; and &man.syslog.conf.5, and perhaps check /etc/syslog.conf to see to which files syslogd is logging). OK, enough of the examples — let us dive into setting up the system. Kernel Configuration FreeBSD's default kernels usually come with two SLIP interfaces defined (sl0 and sl1); you can use netstat -i to see whether these interfaces are defined in your kernel. Sample output from netstat -i: Name Mtu Network Address Ipkts Ierrs Opkts Oerrs Coll ed0 1500 <Link>0.0.c0.2c.5f.4a 291311 0 174209 0 133 ed0 1500 138.247.224 ivory 291311 0 174209 0 133 lo0 65535 <Link> 79 0 79 0 0 lo0 65535 loop localhost 79 0 79 0 0 sl0* 296 <Link> 0 0 0 0 0 sl1* 296 <Link> 0 0 0 0 0 The sl0 and sl1 interfaces shown in netstat -i's output indicate that there are two SLIP interfaces built into the kernel. (The asterisks after the sl0 and sl1 indicate that the interfaces are “down”.) However, FreeBSD's default kernels do not come configured to forward packets (ie, your FreeBSD machine will not act as a router) due to Internet RFC requirements for Internet hosts (see RFC's 1009 [Requirements for Internet Gateways], 1122 [Requirements for Internet Hosts — Communication Layers], and perhaps 1127 [A Perspective on the Host Requirements RFCs]), so if you want your FreeBSD SLIP Server to act as a router, you will have to edit the /etc/rc.conf file (called /etc/sysconfig in FreeBSD releases prior to 2.2.2) and change the setting of the gateway variable to . If you have an older system which predates even the /etc/sysconfig file, then add the following command: sysctl -w net.inet.ip.forwarding = 1 to your /etc/rc.local file. You will then need to reboot for the new settings to take effect. You will notice that near the end of the default kernel configuration file (/sys/i386/conf/GENERIC) is a line that reads: pseudo-device sl 2 This is the line that defines the number of SLIP devices available in the kernel; the number at the end of the line is the maximum number of SLIP connections that may be operating simultaneously. Please refer to Configuring the FreeBSD Kernel for help in reconfiguring your kernel. Sliplogin Configuration As mentioned earlier, there are three files in the /etc/sliphome directory that are part of the configuration for /usr/sbin/sliplogin (see &man.sliplogin.8; for the actual manual page for sliplogin): slip.hosts, which defines the SLIP users & their associated IP addresses; slip.login, which usually just configures the SLIP interface; and (optionally) slip.logout, which undoes slip.login's effects when the serial connection is terminated. <filename>slip.hosts</filename> Configuration /etc/sliphome/slip.hosts contains lines which have at least four items, separated by whitespace: SLIP user's login ID Local address (local to the SLIP server) of the SLIP link Remote address of the SLIP link Network mask The local and remote addresses may be host names (resolved to IP addresses by /etc/hosts or by the domain name service, depending on your specifications in /etc/host.conf), and I believe the network mask may be a name that can be resolved by a lookup into /etc/networks. On a sample system, /etc/sliphome/slip.hosts looks like this: # # login local-addr remote-addr mask opt1 opt2 # (normal,compress,noicmp) # Shelmerg dc-slip sl-helmerg 0xfffffc00 autocomp At the end of the line is one or more of the options. — no header compression — compress headers — compress headers if the remote end allows it — disable ICMP packets (so any “ping” packets will be dropped instead of using up your bandwidth) Note that sliplogin under early releases of FreeBSD 2 ignored the options that FreeBSD 1.x recognized, so the options , , , and had no effect until support was added in FreeBSD 2.2 (unless your slip.login script included code to make use of the flags). Your choice of local and remote addresses for your SLIP links depends on whether you are going to dedicate a TCP/IP subnet or if you are going to use “proxy ARP” on your SLIP server (it is not “true” proxy ARP, but that is the terminology used in this document to describe it). If you are not sure which method to select or how to assign IP addresses, please refer to the TCP/IP books referenced in the slips-prereqs section and/or consult your IP network manager. If you are going to use a separate subnet for your SLIP clients, you will need to allocate the subnet number out of your assigned IP network number and assign each of your SLIP client's IP numbers out of that subnet. Then, you will probably either need to configure a static route to the SLIP subnet via your SLIP server on your nearest IP router, or install gated on your FreeBSD SLIP server and configure it to talk the appropriate routing protocols to your other routers to inform them about your SLIP server's route to the SLIP subnet. Otherwise, if you will use the “proxy ARP” method, you will need to assign your SLIP client's IP addresses out of your SLIP server's Ethernet subnet, and you will also need to adjust your /etc/sliphome/slip.login and /etc/sliphome/slip.logout scripts to use &man.arp.8; to manage the proxy-ARP entries in the SLIP server's ARP table. <filename>slip.login</filename> Configuration The typical /etc/sliphome/slip.login file looks like this: #!/bin/sh - # # @(#)slip.login 5.1 (Berkeley) 7/1/90 # # generic login file for a slip line. sliplogin invokes this with # the parameters: # 1 2 3 4 5 6 7-n # slipunit ttyspeed loginname local-addr remote-addr mask opt-args # /sbin/ifconfig sl$1 inet $4 $5 netmask $6 This slip.login file merely ifconfig's the appropriate SLIP interface with the local and remote addresses and network mask of the SLIP interface. If you have decided to use the “proxy ARP” method (instead of using a separate subnet for your SLIP clients), your /etc/sliphome/slip.login file will need to look something like this: #!/bin/sh - # # @(#)slip.login 5.1 (Berkeley) 7/1/90 # # generic login file for a slip line. sliplogin invokes this with # the parameters: # 1 2 3 4 5 6 7-n # slipunit ttyspeed loginname local-addr remote-addr mask opt-args # /sbin/ifconfig sl$1 inet $4 $5 netmask $6 # Answer ARP requests for the SLIP client with our Ethernet addr /usr/sbin/arp -s $5 00:11:22:33:44:55 pub The additional line in this slip.login, arp -s $5 00:11:22:33:44:55 pub, creates an ARP entry in the SLIP server's ARP table. This ARP entry causes the SLIP server to respond with the SLIP server's Ethernet MAC address whenever a another IP node on the Ethernet asks to speak to the SLIP client's IP address. When using the example above, be sure to replace the Ethernet MAC address (00:11:22:33:44:55) with the MAC address of your system's Ethernet card, or your “proxy ARP” will definitely not work! You can discover your SLIP server's Ethernet MAC address by looking at the results of running netstat -i; the second line of the output should look something like: ed0 1500 <Link>0.2.c1.28.5f.4a 191923 0 129457 0 116 This indicates that this particular system's Ethernet MAC address is 00:02:c1:28:5f:4a — the periods in the Ethernet MAC address given by netstat -i must be changed to colons and leading zeros should be added to each single-digit hexadecimal number to convert the address into the form that &man.arp.8; desires; see the manual page on &man.arp.8; for complete information on usage. When you create /etc/sliphome/slip.login and /etc/sliphome/slip.logout, the “execute” bit (ie, chmod 755 /etc/sliphome/slip.login /etc/sliphome/slip.logout) must be set, or sliplogin will be unable to execute it. <filename>slip.logout</filename> Configuration /etc/sliphome/slip.logout is not strictly needed (unless you are implementing “proxy ARP”), but if you decide to create it, this is an example of a basic slip.logout script: #!/bin/sh - # # slip.logout # # logout file for a slip line. sliplogin invokes this with # the parameters: # 1 2 3 4 5 6 7-n # slipunit ttyspeed loginname local-addr remote-addr mask opt-args # /sbin/ifconfig sl$1 down If you are using “proxy ARP”, you will want to have /etc/sliphome/slip.logout remove the ARP entry for the SLIP client: #!/bin/sh - # # @(#)slip.logout # # logout file for a slip line. sliplogin invokes this with # the parameters: # 1 2 3 4 5 6 7-n # slipunit ttyspeed loginname local-addr remote-addr mask opt-args # /sbin/ifconfig sl$1 down # Quit answering ARP requests for the SLIP client /usr/sbin/arp -d $5 The arp -d $5 removes the ARP entry that the “proxy ARP” slip.login added when the SLIP client logged in. It bears repeating: make sure /etc/sliphome/slip.logout has the execute bit set for after you create it (ie, chmod 755 /etc/sliphome/slip.logout). Routing Considerations If you are not using the “proxy ARP” method for routing packets between your SLIP clients and the rest of your network (and perhaps the Internet), you will probably either have to add static routes to your closest default router(s) to route your SLIP client subnet via your SLIP server, or you will probably need to install and configure gated on your FreeBSD SLIP server so that it will tell your routers via appropriate routing protocols about your SLIP subnet. Static Routes Adding static routes to your nearest default routers can be troublesome (or impossible, if you do not have authority to do so...). If you have a multiple-router network in your organization, some routers, such as Cisco and Proteon, may not only need to be configured with the static route to the SLIP subnet, but also need to be told which static routes to tell other routers about, so some expertise and troubleshooting/tweaking may be necessary to get static-route-based routing to work. Running <command>gated</command> An alternative to the headaches of static routes is to install gated on your FreeBSD SLIP server and configure it to use the appropriate routing protocols (RIP/OSPF/BGP/EGP) to tell other routers about your SLIP subnet. You can use gated from the ports collection or retrieve and build it yourself from the GateD anonymous ftp site; I believe the current version as of this writing is gated-R3_5Alpha_8.tar.Z, which includes support for FreeBSD “out-of-the-box”. Complete information and documentation on gated is available on the Web starting at the Merit GateD Consortium. Compile and install it, and then write a /etc/gated.conf file to configure your gated; here is a sample, similar to what the author used on a FreeBSD SLIP server: # # gated configuration file for dc.dsu.edu; for gated version 3.5alpha5 # Only broadcast RIP information for xxx.xxx.yy out the ed Ethernet interface # # # tracing options # traceoptions "/var/tmp/gated.output" replace size 100k files 2 general ; rip yes { interface sl noripout noripin ; interface ed ripin ripout version 1 ; traceoptions route ; } ; # # Turn on a bunch of tracing info for the interface to the kernel: kernel { traceoptions remnants request routes info interface ; } ; # # Propagate the route to xxx.xxx.yy out the Ethernet interface via RIP # export proto rip interface ed { proto direct { xxx.xxx.yy mask 255.255.252.0 metric 1; # SLIP connections } ; } ; # # Accept routes from RIP via ed Ethernet interfaces import proto rip interface ed { all ; } ; The above sample gated.conf file broadcasts routing information regarding the SLIP subnet xxx.xxx.yy via RIP onto the Ethernet; if you are using a different Ethernet driver than the ed driver, you will need to change the references to the ed interface appropriately. This sample file also sets up tracing to /var/tmp/gated.output for debugging gated's activity; you can certainly turn off the tracing options if gated works OK for you. You will need to change the xxx.xxx.yy's into the network address of your own SLIP subnet (be sure to change the net mask in the proto direct clause as well). When you get gated built and installed and create a configuration file for it, you will need to run gated in place of routed on your FreeBSD system; change the routed/gated startup parameters in /etc/netstart as appropriate for your system. Please see the manual page for gated for information on gated's command-line parameters. Acknowledgments Thanks to these people for comments and advice regarding this tutorial: &a.wilko; Piero Serini Piero@Strider.Inet.IT