[CentOS] problem on exceptional quit

Thu Oct 8 23:23:48 UTC 2015
Gordon Messmer <gordon.messmer at gmail.com>

On 10/07/2015 07:33 PM, Hua Wang wrote:
> I installed Centos 7 on my server a few months ago. While using ssh, there is always a strange message "Write failed: Broken pipe”.

That's very often a result of IP conflict.  I'm assuming that you're 
connecting to an IPv4 address.  If so, log in to your CentOS server and 
use arping to look for conflicts:

# arping -c 2 D -I em1 <your address>

> 1. Login via Mac, Windows, Linux systems from different computers.
> 2. Modify sshd_config on the server as suggested by many posts:
> TCPKeepAlive yes
> ClientAliveInterval 60

TCPKeepAlive is "yes" by default.  ClientAliveInterval doesn't appear to 
be a valid setting.  Either TCPKeepAlive or ServerAliveInterval could be 
useful if the problem were a stateful firewall which was dropping your 
connection from its state table, and then resetting the connection in 
response to a later packet from your client.

Since those don't help, that tends to suggest that the problem isn't an 
intermediate host, but the server itself.  Possibly an IP conflict.  
Also, check the output of "dmesg" to see if there are any problems 
recorded with the NIC.  Check the output of "ifconfig" to see if there 
are TX or RX errors that increase when your connections are reset.

> 3. Modify ~/.ssh/config file on my local computer:
> Host *
> ServerAliveInterval 60
> 4. Login ssh using -Y instead of -X.

You didn't say what client OS you're using, but Fedora and CentOS set 
ForwardX11Trusted to "yes" by default, so "ssh -Y" is the same as "ssh 
-X".  And even if it weren't, it wouldn't cause the problem you're seeing.

> 5. add ‘unset autologout’ in my .cshrc.

The error you're seeing won't be triggered by your shell exiting.

> 6. I checked IP address with the internet administrator, and it works well.
> 7. add a file named autologout.csh with ‘set autologout=0’.