[gentoo-user] Where to put advanced routing configuration?

[Grant Edwards <grant.b.edwards@gmail.com>]

Let's say you wanted to configure routing of TCP packets based on destination 
port like in this example:

  http://www.tldp.org/HOWTO/Adv-Routing-HOWTO/lartc.netfilter.html

[which contains a series of 'ip' and 'iptables' commands to get packets
destined for port 25 to use a specific gateway.]

How do do this the "right" way on a Gentoo system?

Based on reading http://www.gentoo.org/doc/en/home-router-howto.xml, I think 
I've figured out how to do the iptables part: you enter the 'iptables' 
commands by hand to get the iptables set up the way you want, then you do 
this:

  # /etc/init.d/iptables save
  # rc-update add iptables default

What about the 'ip' commands required to set up the tables, routes, and 
rules?  Do those go in a startup script somewhere? Does one just edit 
/etc/iproute2/rt_tables by hand? One would assume route configuration belongs 
in /etc/conf.d/net -- I've read through the advanced networking stuff in the 
handbook, but it's not apparent to me where those 'ip' command belong.

-- 
Grant