Adding an additional IP Address to an Ethernet interface

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Tomas
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Joined: 15 Sep 2008, 15:57
Location: Clavister HQ - Örnsköldsvik

Adding an additional IP Address to an Ethernet interface

Post by Tomas » 03 Feb 2014, 13:36

This FAQ applies to:
  • Clavister CorePlus and cOS Core, any version.
Question:

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

Answer:
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

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