Multiple Subnets on the Same NIC

[BarryStiefel]

Multiple Subnets on the Same NIC



Most OSes will allow you to have multiple IP addresses associated with the same NIC. The IPs can be on the same logical network or on a different logical subnet. The instructions for this vary by OS. On Solaris (and possibly others), you should be able to create a secondary IP by doing something like an "ifconfig le0:1 a.b.c.d up". On Windows, you can click on the "Advanced" tab in the TCP/IP config to configure more than one IP address. IPSO will allow for multiple IPs for the same interface by simply adding them in Voyager, though each IP must be on different subnets.

FireWall-1 will handle more than one IP address assigned to the same NIC. Only the physical interface should be listed in your interfaces tab. Also, your anti-spoofing will need to be configured so that the extra subnets are considered "valid" for that physical NIC.

One issue that comes up with this is that any rule that involves your firewall workstation object will not include the virtual IPs unless they are explicitly added as interfaces to the object. You can use any interface name for these interfaces.

-- PhoneBoy - 10 Jan 2004

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