CentOS - Jan 2013 - Openssh connection closes from time to time. why?

Hey there,

I just replaced long lived Gentoo to a Centos 6.3 on 2 servers.
Since the move I had troubles with ssh open sessions.
I am connecting from a windows machine via putty and then all of a 
sudden it saying something about connection closing.
The OpenSSH version is: openssh-server-5.3p1-81.el6.x86_64.rpm
I tired to configure:
tcp_keep_alive
TCPKeepAlive yes
ClientAliveInterval 240
ClientAliveCountMax 50

Each one of them or all together seems to not solve the problem.
It's not iptables issue since it was stopped and disabled.

If someone have an idea of what can be done or checked I will be happy 
to hear about it.

For now I have created a custom OpenSSH-6.1p1 RPM just in case it will 
might help.

Both server has the same issue while another Fedora machine runs by 
which doesn't have the same issues.

They are both connected to the same switch and seems to be fine.

Thanks,
Eliezer

Sorry my Bad.
The local dhcp server of the router is broken and causes a deny for the 
dhcp-ack for about 5 secs and that causes the machine to drop the IP 
lease for about 5 secs.

If someone want OpenSSH v6.1p1 I have a RPM on my repo.

Thanks,
Eliezer


On 1/3/2013 9:45 AM, Eliezer Croitoru wrote:
> Hey there,
>
> I just replaced long lived Gentoo to a Centos 6.3 on 2 servers.
> Since the move I had troubles with ssh open sessions.
> I am connecting from a windows machine via putty and then all of a
> sudden it saying something about connection closing.
> The OpenSSH version is: openssh-server-5.3p1-81.el6.x86_64.rpm
> I tired to configure:
> tcp_keep_alive
> TCPKeepAlive yes
> ClientAliveInterval 240
> ClientAliveCountMax 50
>
> Each one of them or all together seems to not solve the problem.
> It's not iptables issue since it was stopped and disabled.
>
> If someone have an idea of what can be done or checked I will be happy
> to hear about it.
>
> For now I have created a custom OpenSSH-6.1p1 RPM just in case it will
> might help.
>
> Both server has the same issue while another Fedora machine runs by
> which doesn't have the same issues.
>
> They are both connected to the same switch and seems to be fine.
>
> Thanks,
> Eliezer
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