Problems setting up DNS, gateway und subnetmask!

[David Hart]

On Wed, Dec 28, 2005 at 02:07:02AM +0200, Tamer Higazi wrote:
> Hi!
> I have received from my ISP an IP, DNS, Subnetmask and the DNS 
> Serverentries to add to my ubuntu linux machine

Does your ISP not have a DHCP server to save messing about with manual
settings?

If they do then go to System -> Administration -> Networking
and set eth0 to DHCP.
 
[snip]
> auto eth0
> 
> iface eth0 inet static
> address 81.10.53.22
> netmask 255.255.255.252

The netmask above only allows for four addresses one of which is the
network address (81.10.53.20), another for broadcast (81.10.53.23), your
IP (81.10.53.22), which means the gateway must be 81.10.53.21.

> gateway 10.0.0.138

That IP is not routeable on the Internet (it's private address space)
and won't work with your netmask.

Perhaps you should check the addresses you've been given or, as I said
at the top, use the Networking applet and set it to DHCP.

[snip]
> If I enter the command route:
> 
> Kernel IP Routentabelle
> Ziel Router Genmask Flags Metric Ref Use Iface
> 81.10.53.20 * 255.255.255.252 U 0 0 0 eth0
> 
> If I run explicitly this command to add the gateway to my eth0 interface:
> 
> 
> sudo route add default gateway 10.0.0.138 eth0
> 
> I receive this errormessage:
> SIOCADDRT: Das Netzwerk ist nicht erreichbar (Network unreachable)

That's because of your netmask and the private IP address of the
gateway.

-- 
David Hart <ubuntu at tonix.org>