Two or more network interfaces

Suppose that we have an additional network interface ethX with a network n.n.n.n/n, an ip address a.a.a.a, and a gateway g.g.g.g.

• Add a routing table to /etc/iproute2/rt_tables:

#
# reserved values
#
255     local
254     main
253     default
0       unspec
#
# local
#
#1      inr.ruhep
1 rt1

• Add

if /sbin/ip -4 route show | grep -wq "n.n.n.n/29 dev ethX"; then
  /sbin/ip -4 route del n.n.n.n/29 dev ethX
fi
if ! /sbin/ip -4 route show table rt1 | grep -wq "n.n.n.n/29 dev ethX"; then
  /sbin/ip -4 route add n.n.n.n/29 dev ethX scope link src a.a.a.a table rt1
fi
if ! /sbin/ip -4 route show table rt1 | grep -wq default; then
  /sbin/ip -4 route add default via g.g.g.g dev ethX table rt1
fi
if ! /sbin/ip -4 rule show | grep -wq "lookup rt1"; then
  /sbin/ip -4 rule add from a.a.a.a/32 table rt2
  /sbin/ip -4 rule add to a.a.a.a/32 table rt2
fi

to the end of IPv4 section of the function gateway_up in /etc/rc.d/rc.inet1

• Add

if /sbin/ip -4 route show table rt1 | grep -wq "n.n.n.n/29 dev ethX"; then
  /sbin/ip -4 route del n.n.n.n/29 dev ethX table rt1
fi
if /sbin/ip -4 route show table rt1 | grep -wq default; then
  /sbin/ip -4 route del default table rt1
fi
if /sbin/ip -4 rule show | grep -wq "lookup rt1"; then
  /sbin/ip -4 rule del from a.a.a.a/32 table rt1
  /sbin/ip -4 rule del to a.a.a.a/32 table rt1
fi

to the end of IPv4 section of the function gateway_down in /etc/rc.d/rc.inet1

• # /etc/rc.d/rc.inet1 restart