5.26. Routing Protocols

Routing and routing protocols can create several problems. The IP source routing, where an IP packet contains details of the path to its intended destination, is dangerous because according to RFC 1122 the destination host must respond along the same path. If an attacker was able to send a source routed packet into your network, then he would be able to intercept the replies and fool your host into thinking it is communicating with a trusted host. I strongly recommend that you disable IP source routing to protect your server from this hole.

To disable IP source routing on your server, type the following command in your terminal:

              [root@deep] /# for f in /proc/sys/net/ipv4/conf/*/accept_source_route; do
              > echo 0 > $f
              > done
              

              [root@deep] /#
              

              # Disables IP source routing
              net.ipv4.conf.all.accept_source_route = 0
              

              [root@deep] /# /etc/rc.d/init.d/network restart
              

Setting network parameters [ OK ] Bringing up interface lo [ OK ] Bringing up interface eth0 [ OK ] Bringing up interface eth1 [ OK ]