Re: [opensuse] Two NIC's, one connected, Ping Both...?

At 02:06 AM 7/14/2008, Brian K. White wrote:

----- Original Message ----- From: "William Hammond" <tech@xxxxxxxxxxx>
To: "open SuSE mail list" <opensuse@xxxxxxxxxxxx>
Sent: Monday, July 14, 2008 4:24 AM
Subject: [opensuse] Two NIC's, one connected, Ping Both...?


The real problem here is that I so far have been unable to connect
to a remote 10.3 Server.

Firewall is active, but all necessary ports are open,
Server is behind a Router, and the Router is doing Port Forwarding.
the this case, 5901,5801,22 ---

This is the only site I can;t get into with Putty. (SSH on 22)

One thing that bothers me is the Server.

Like most modern boards it has two built in NIC.s and 100MB and a 1GB.
Both are configured with Private IP's xxx.xxx.xxx.200 and xxx.xxx.xxx.201
(I bet nobody can guess what the xx's represent.. ;-) )

Only one of these RJ45 Ports is connected, but I can Ping them both.

Is that normal...? and is it okay..? or could it be part of my problem..?

It's perfectly normal.
If you configured any nic with an ip, whether it's connected or not, and couldn't ping it from localhost, that would be an indication the nic was bad. Not counting completely broken firewall rules.

I should have been more clear, I can ping both from local XP workstations (everything is behind the router), not just inside the box. It just seemed to me that I should only be
able to ping the active NIC. So when setting up Port Forwarding I couldn't be sure which was active.
The commands you gave me later in this message will solve that.


Start by turning off the firewall, double-checking that you are running ssh, and connecting from a localhost. ie:
rcSuSEfirewall2 stop
chkconfig sshd on
rcsshd start
ssh localhost.

Thanks, these are some of the commands I needed


If that works then leave the firewall off and connect (ssh) from a local pc on the lan.

If that works then enable the firewall and try again

If that works then try connecting(ssh) from remote.

What to look for depends on which of the above works and doesn't work.

For example:
If you turn the firewall off and still can't ssh localhost, then you are most likely not running sshd.
Either way, check netstat -an for attempted tcp connections, and check syslog for possible messages from sshd or possibly the kernel ip filter.

After that comes various routing/netmask/firewall things but I can't very well write the entire process of debugging a service access problem in an email.

Don't rely on ping unless you _know_ that all routers and switches between you & the target are passing icmp.
It's more and more common for routers to block icmp (ping, traceroute, etc) these days. You can't ping through one of those.

Are the basic network settings correct?
ip, netmask, default-route, nameserver(s)?
ifconfig -a
netstat -rn
cat /etc/resolv.conf

Again, thanks for taking time to give me a diagnostics plan... These are the steps I'm not familiar with in Linux...


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