Although not strictly necessary for a firewall, you may need to implement routing on your RHEL7 system. Often, this will be associated with multi-homed systems with more than one network interface card; however, this is not a requirement of network routing, which allows packets to be forwarded to the correct destination network. Network routing is enabled in
procfs in the
/proc/sys/net/ipv4/ip_forward file. If this file contains a value of
0, then routing is disabled; if it has a value of
1, routing is enabled. This can be set using the
echo command as follows:
# echo 1 > /proc/sys/net/ipv4/ip_forward
However, this is then turned on until the next reboot when the routing will revert to the configured setting. To make this setting permanent ...