topic Re: network will not work in Operating System - Linux

network will not work

Rick Garland — Thu, 21 Sep 2006 15:52:53 GMT

Hi all:

RHEL4 U4 on ProLiant DL360 G5

The OS loaded fine without troubles, the startup says "bring up eth0 - success" but still unable to connect to the system.

Unable to ping the gateway but can ping the localhost

Checked the /etc/sysconfig/network-scripts and looks OK.

Where else could I look?

Thanks

Re: network will not work

Ivan Ferreira — Thu, 21 Sep 2006 16:22:51 GMT

Ensure that iptables is stopped:

service iptables stop

Check that the network link is detected:

ethtool eth0

Ensure that you receive packets, check RX OK from the output of:

ifconfig
netstat -ni

Re: network will not work

Steven E. Protter — Fri, 22 Sep 2006 01:23:03 GMT

Shalom Rick,

iptables is a good start, but if things were set right the system should still be on the network.

1) More basic, check the link light. If its not on, check the switch if its on move down this list.

2) On another machien check the arp table with the arp command. See if somone is on the network with the same ip address.

3) ping -b broadcast address see whats out there.

4) Try setting up eth1, maybe eth0 is bad.

I'll post back when I'm awake and something normal comes to mind.

SEP

Re: network will not work

Alexander Chuzhoy — Fri, 22 Sep 2006 01:54:56 GMT

Hi Rick,
if the network card wasn't configured as DHCP client, then "bring up eth0" doesn't necessarily means that it's IP resides in apropriate LAN. Unless you've found the solution already you can post the /etc/sysconfig/network and /etc/sysconfig/network-scripts/ifcfg-eth{0,1} and the output of ethtool eth0 and ethtool eth1.
One more thing to try-replace the network cable.

Re: network will not work

Al Licause — Fri, 22 Sep 2006 08:16:44 GMT

If this system has more than one network card, make sure that your network cable is plugged into what you think is eth0.

You'd be surprised at how many customers make this mistake. And with linux and the methods it uses to discover network devices, what you think is eth0 may not be......or it can move from boot to boot.

Re: network will not work

timmy2006 — Wed, 08 Nov 2006 01:28:33 GMT

1. check cable (light or flashing)
2. ifconfig -a (check if iface is up)
3. try ping locally not 'localhost', but your machine ip on eth0\1\2.
try manually:
A) /etc/init.d/network stop
(imho i was a bad idea to start\stop net from init.d)

B) /etc/init.d/iptables stop (or any kind of FW you are using)

C) /sbin/ifconfig eth0 IP_ADDR netmask NET_MASK broadcast BCAST up

D) use tcpdump after that to listen for packets.

Re: network will not work

Alpha977 — Tue, 14 Nov 2006 07:35:21 GMT

Hello!

try to shut-down all iptables rules on both eth and try if the machine is reachable from another machine.

Also, use a sniffer like "tcpdump" or "ethereal" on linux and another machine to see the inbound-outbound traffic.