11.4.5. 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.

11.4.5.1. Static Routes

Adding static routes to your nearest default routers can be troublesome (or impossible, if you don't 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.

11.4.5.2. Running gated

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. gated is available via anonymous ftp from ftp.gated.cornell.edu in the directory /pub/gated; 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 http://www.gated.cornell.edu/. Compile and install it, and then write a /etc/gated.conf file to configure your gated; here's a sample, similar to what the author used on a FreeBSD SLIP server:

----- begin sample /etc/gated.conf for gated version 3.5Alpha5 -----
#
# 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 ;
} ;

----- end sample /etc/gated.conf -----

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'll 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'll 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'll 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.