Assigning multiple IPs in the same network to an interface

[Damien Fleuriot]

On 2/16/12 8:08 AM, M. V. wrote:
> hi everybody,
> 
> i have a problem with setting multiple IPs in the same network in FreeBSD:
> 
> - suppose I assign two new IP addresses in the same network to eth0 with ifconfig:
> #ifconfig eth0 add 192.168.10.1/24
> #ifconfig eth0 add 192.168.10.2/24
> 
> - everything works fine and the output of "netstat -r" is like what it should be:
> #netstat -r
> ....
> 192.168.10.0   eth0
> 192.168.10.1    lo0
> 192.168.10.2    lo0
> ...
> 
> - but now if I delete first IP address, connection to 192.168.10.0 network will be gone. and in output of "netstat -r" the route to 192.168.10.0 (via eth0) is gone:
> #ifconfig eth0 delete 192.168.10.1
> 
> #netstat -r
> ....
> 
> 192.168.10.2    lo0
> .....
> 
> - am i missing something here? shouldn't the route to the network remain in routing table (because we still have 192.168.10.2 assigned to interface)?
> 
> Thanks.
> 

You shouldn't assign your secondary IP with a /24 mask, use /32.

You'll run into problems otherwise.

As a rule of thumb, your aliases = /32