Hey,

Im having problems with the loopback interface.

I cant get a ping reply from it.

My ifconfig returns:


lo Link encap:Local Loopback
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)


Seems not to be configured correctly?

Any help fixing?

Many thanks.

What does your /etc/hosts file look like?

im doing ping 127.0.0.1

But my file:

127.0.0.1 localhost.localdomain localhost

can you copy paste the exact command ran and the output? can you ping other IP address?

I can ping external addresses and the internet address assigned in ifconfig.

The exact command im using is:

ping 127.0.0.1
PING 127.0.0.1 (127.0.0.1) 56(84) bytes of data.

--- 127.0.0.1 ping statistics ---
3 packets transmitted, 0 received, 100% packet loss, time 1999ms


It just hangs after this, so i control + c.

whast the output of 'iptables -L'

Chain FORWARD (policy ACCEPT)
target prot opt source destination

Chain INPUT (policy ACCEPT)
target prot opt source destination

Chain OUTPUT (policy ACCEPT)
target prot opt source destination

Check the host.allow, host.deny files. Maybe the problem is there.

Both are empty.

Very interesting. Have you tried looking at your configuration scripts for the NIC card? Try looking into the script for the "localloopback" in the network scripts folder of your OS, if there is one. Since you didn't list your distribution this may not help you much but if you are using Red Hat/Fedora, try this folder:

"/etc/sysconfig/network-scripts/"

Edit the file that resembles the loopback interface accordingly. If you don't have this folder or file, manually enter the information for the lo interface as root and see if that works. If it does, you can make a script of that command and have it run on startup.

"ipconfig lo 127.0.0.1 netmask 255.0.0.0"

Hi, thanks for the reply.

Im using Fedora Core 3.

In the directory you said i have:

ifcfg-lo ifdown-ipv6 ifup-aliases ifup-isdn ifup-sl
ifdown ifdown-isdn ifup-bnep ifup-plip ifup-wireless
ifdown-aliases ifdown-post ifup-eth ifup-plusb init.ipv6-global
ifdown-bnep ifdown-ppp ifup-ippp ifup-post network-functions
ifdown-eth ifdown-sit ifup-ipsec ifup-ppp network-functions-ipv6
ifdown-ippp ifdown-sl ifup-ipv6 ifup-routes
ifdown-ipsec ifup ifup-ipx ifup-sit


I cant see any called "loopback" (i have tried ls -al).

I have just ran:

""ifconfig lo 127.0.0.1 netmask 255.0.0.0"

And i can now ping 127.0.0.1.

I think my origional post does not show a subnet mask for the lo interface...

Could you just go over how i can fix this permenantly.

Many thanks for the help.

*EDIT

i have just looked in ifcfg-lo, it seems correct:

DEVICE=lo
IPADDR=127.0.0.1
NETMASK=255.0.0.0
NETWORK=127.0.0.0
# If you're having problems with gated making 127.0.0.0/8 a martian,
# you can change this to something else (255.255.255.255, for example)
BROADCAST=127.255.255.255
ONBOOT=yes
NAME=loopback

Ok this is where my true newbie colors show. I haven't played with startup scripts in a while so it may help id you back this up with a little more research.

It would be best to isolate this problem but a patch can work until you have time .

Here is what I have for the script:

Make this file in the /etc/rc.d/init.d/ folder under the name of lo.

If it doesn't work, post saying so. I'm not at home at the moment and can't try it out but I can later on when I get off.

I do hope that this works though.

Good luck!

Yea thanks, least i know what the problem was now.

Cheers!

This was driving me mad and stopping things from working.