Unable to SSH to eth0. But not eth1

hhvv · 09-11-2009, 01:13 AM

Hi Folks,
I am unable to SSH to RHEL4 on eth0 which is having an IP, lets say 10.1.0.1. But at the same time eth1 (10.1.0.2) is working fine. And if I assign 10.1.0.2 on eth0 that's working fine. In other way if I assign 10.1.0.1 on eth1 it works.
No IPTABLES, TCP Wrapper or SELinux is enabled. Please help. Tried SSH restart and even reboot.
In the remote machine it's giving the error "ssh_exchange_identification: read: Connection reset by peer". And in TCPDUMP we found the same TCP RESET flag during Handshake. Machine is behind a vLAN with no ACLs or restrictions.

acid_kewpie · 09-11-2009, 05:40 AM

why do you have to IP's on the same subnet on different NIC's???

hhvv · 09-11-2009, 08:31 AM

Hi Chris,
We were running with a single IP on eth0. Just for troubleshooting purpose we configured eth1 with a new IP. We did a ifdown eth1 after that. And one more thing, if we create eth0:0 it works like a charm.
Thanks for our reply. In hope of some tricks

here....

acid_kewpie · 09-11-2009, 02:25 PM

well a trick would be to NOT use multiple interfaces on the same network. do as you did eht eth0:0 instead, or if you do want two physical interfaces, then a bond module making eth0 and eth1 into a bond0 interface, and then haave a bond0 and a bond0:0.

never say never · 09-11-2009, 02:34 PM

Sounds like a routing issue.

Take a look at route and you will probably see one nic is set as the gateway for both IPs. That would explain why it worked as eth0:0 but not as eth1.

If this doesn't explain it post the output of ifconfig and route and make certain there is no firewalling in place. Are the connected to the same switch? What is the IP of the other machine?

More information is needed to be certain of the problem.

Let us know. . .

hhvv · 09-12-2009, 03:18 AM

Thanks a lot for your reply.
I really don't want 2 NICs as mentioned in the previous post. Just for ensuring there is no problem with SSH I tried enabling it. Now it has been removed.
And then, the problematic machine and the client machines are connected to the same switch. Even the eth1 was connected to the same Switch. There is no network firewall, IPTABLES, TCP Wrapper or SELinux. And the SSH was working previously. All of a sudden it got stuck. I don't remember any change in the server recently in these days of issue.

hhvv · 09-19-2009, 02:58 AM

Hi All,
Removed eth0. Assigned the same IP to eth1. It's working. But still no idea about why that IP is not working with eth0.