Re: IP aliasing/Virtual IP's in 2.2.19 or 2.4.10

J Sloan (
Wed, 26 Sep 2001 12:09:59 -0700

Steve Pirk wrote:

> This much I have found so far...
> In /usr/src/linux-2.2.16/.config :
> In /usr/src/linux-2.2.19/.config
> no CONFIG_IP_MASQUERADE lines at all....
> Would it be save to add them to a 2.2.19 or 2.4.10 .config file?

bad idea -

> Is aliasing/masquerading enabled by default in kernel versions
> above 2.2.19?

I think it's a default feature in 2.4.x since I don't
see a config file option for it and it works fine on
all my boxen -

Let's check the docs:

Ah, here it is - and it matches my experience -


IP-aliases are additional IP-adresses/masks hooked up to a base
interface by adding a colon and a string when running ifconfig.
This string is usually numeric, but this is not a must.

IP-Aliases are avail if CONFIG_INET (`standard' IPv4 networking)
is configured in the kernel.

o Alias creation.
Alias creation is done by 'magic' interface naming: eg. to create a alias for eth0 ...

# ifconfig eth0:0 etc,etc....
~~ -> request alias #0 creation (if not yet exists) for eth0

The corresponding route is also set up by this command.
Please note: The route always points to the base interface.

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