I have several static IP addresses and have one assigned to my Debian 4 machine. This machine has 2 NICs. eth0 is the local network (192.168.0.1/24) and eth1 is the public IP (we'll say 204.87.256.58/29 - yes, I know this is an invalid IP address....). Currently .58 is assigned to eth1 and works. I wanted to add a second IP and edited my /etc/network/interfaces file to reflect this:

auto eth1
iface eth1 inet static
address 204.87.256.58
netmask 255.255.255.248
network 204.87.256.56
broadcast 204.87.256.63
gateway 204.87.256.57
# dns-* options are implemented by the resolvconf package, if installed
dns-nameservers 256.55.140.11 70.260.207.137
dns-search mydomain.com

auto eth1:0
iface eth1:0 inet static
address 204.87.256.59
netmask 255.255.255.248
gateway 204.87.256.57


Now when I restart the service (/etc/init.d/networking restart) the new IP shows, but I cannot ping it from outside - maybe my firewall, but we'll get to that next. I run 'ifconfig eth1:0 down', and then try to brin it back up with 'ifconfig eth1:0 up' but get this error:

mc1:/etc/network# ifconfig -v eth1:0 up
SIOCSIFFLAGS: Cannot assign requested address
WARNING: at least one error occured. (-1)

This IP USED to be assigned to a Redhat box, but I've since given it a new IP so this one was open. Can anyone see where I went wrong or fat-fingered something?
Thanks.

I am not sure you can assign a gateway on Alias IPs. I think the Alias IP scheme handles that for you. Just never done this on a Debian system. Only Redhat machines.

Brian

I just tried this in a Ubuntu virtual machine inside Parallels. Though I was able to turn the virtual alias interface down. Trying to start it using ifconfig eth0:0 up yields,

Same problem I'm getting.
Works fine on my RH machine tho.

Maybe this quick google hit might help.
http://www.cyberciti.biz/faq/bind-al...ress-in-linux/

Brian

Tried that. That's what my interfaces file looks like (with different IP addresses of course). Bringing interface down then back up gives the error about not being able to assign the address.

You can try by skipping the alias and using:
ip addr add 204.87.256.59/29 dev eth1

This will assign multiple IP's to the outside interface. Definitely make sure to include this in the firewall rules.

The command returned no erros, but the extra IP did not show in ipconfig, nor can I ping it (I'm accepting ICMP traffic on the other IP assigned to eth1, so I assume that the new IP would be blanketed as well).
Thanks though!

Maybe it's my NIC? Maybe it doesn't support alias addresses? (I'm shooting in the dark here)

Try using ip addr to see if you can see the IP. You should also check your firewall logs to see if it is blocking your attempts to connect.

The IP shows there, but not under ifconfig.
I'll work on the firewall later this week and get back to you.
Thanks!