why is that?eth0
 

Do u know what the following error means? After this command the interface is up and works perfectly
ifconfig eth0 192.168.64.11 255.255.255.0
SIOCSIFADDR: Invalid argument

Syntax of the command is not correct, although ifconfig 'guesses' the correct syntax.
Correct syntax:

ifconfig eth0 up 192.168.64.11 netmask 255.255.255.0

See man ifconfig.

SIOCSIFADDR: Invalid argument

this error message is harmless. I can't remember which program was causing it I think either DNS or DHCP. But it is perfectly fine. Just Ignore it

The same error appears

eth 0 problem
 

hello


solution is simple u were writiing incorrect command


try this

[root@localhost root] ifconfig eth0:0 192.168.0.12 netmask 255.255.255.0 up



it would work now after that restart network

[root @localhost root] service network restart


regards

Thx for your reply but waht eth0:0 means?

what eth0:0 means
 

hello

well eth0 is the secondary ethernet card by writing eth0:0 means that we are binding new setting on eth0 of 0 means updating our eth0 configurations

regards

Canu expmlain this? "......well eth0 is the secondary ethernet "

eth0 confusion
 

hello

well yes eth0 is the secondart ethernet card

regards

I was thinking that the second ethernet inteface was the eth1... I have 2 ethernet cards in my pc and the first one is the eth0 and the second one the eth1... What;s the wrong with that?

Nothing, it's might even be considered as 'better'.

You have 2 hardware devices (network cards), both devices have an IP number attached to it.

eth0 = 1.2.3.4
eth1 = 4.3.2.1

The eth0 notation is a short notation for eth0:0.

It is possible to attach different IP's to 1 hardware device.
eth0:0 = 1.2.3.4 (eth0 for short)
eth0:1 = 1.2.3.5
.
.
eth0:N = 1.2.3.N

In 'normal' situations you do not need to attach more then 1 IP to a network device.

For now just attach 1 IP number to a physical device and keep in mind that ethX:0 is short for ethX.

Hope this clears things up a bit.

"It is possible to attach different IP's to 1 hardware device.
eth0:0 = 1.2.3.4 (eth0 for short)
eth0:1 = 1.2.3.5
.
.
eth0:N = 1.2.3.N"



It sounds great but do u know some reasons for doing that? If an interface has more than one ip then it responds to all requests from all rthe networks?

In general you will not do this, but here are a few reasons:

- Simulate a second (third, fourth) network. Reason: No real network device can be placed (lack of money, slots), testing etc.
- Build (more) redundancy into your network. Reason: Network must have a high 'up-time'.
- Just for fun :)

If the rest of the network is setup correctly it will rrespond to all the IP numbers it has.

It has a few downsides:
- If network device fails, most (all) network connections going thru that device are gone,
- The capacity of the line might become a problem now that is has to pass the data of multiple networks instaid of one.

Thx again for your reply...but how u connect such an interface to multiple networks? A hub or a switch can connect interfaces in the same network....

You gave the naswer to that one: Routers, switches and hubs can be used.

Is it possible for doing something like that in a router?
A router's interface with more than one ip addresses???

I'm 'just' a unix admin, not a network specialist. So I don't know what can be done with routers/switches (hubs are just 'dumb' pass thru boxes).

But it should not be that hard to do, a packet send over the network has a source and destination, as long as the network hardware (routers etc) knows where the destination can be found it can send the packet that way. I.e. normal behaviour for correctly configured network hardware.