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Adding an additional IP Address to an Ethernet interface

Posted: 03 Feb 2014, 13:36
by Tomas
This FAQ applies to:
  • Clavister CorePlus and cOS Core, any version.

How do I add an additional IP Address to an Ethernet interface?

There are at least three different methods to do this. The "best" one is number one (1), as it supports ranges and since the IPs are core routed, a gratuitous ARP will be generated upon bootup, which informs surrounding equipment of the current MAC address for this IP. Valuable when replacing a firewall (RMA etc).

1. IPv4Route interface=core, network=new_ip, proxyARP=wan (or whichever Interface it should be added to). New_ip can be a range of IPs.
2. ARP Publish = new_ip
3. ARP Publish = new_ip plus an IPv4Route with interface=core network=new_ip (but NO ProxyARP, as the ARP Publish handles that).

Methods 1 and 3 will respond to ping if you add a simple Allow rule with destination interface = core. Method 2 requires a SAT rule etc to respond to ping.

To configure multiple networks behind the same interface, see: viewtopic.php?f=18&t=4546