SSH keeps hanging up...

Kimball Larsen kimball at
Tue May 27 10:39:08 MDT 2008

On May 24, 2008, at 7:36 PM, Frank Sorenson wrote:

> Hash: SHA1
> Lonnie Olson wrote:
>> On Wed, May 21, 2008 at 11:07 PM, Kimball Larsen
>> <kimball at> wrote:
>>> I occasionally have to remotely admin a server at the office from  
>>> home.
>>> I have it set up to only allow a few hosts access via ssh, and my  
>>> home
>>> static IP is on the permitted list. (using hosts.allow, hosts.deny)
>>> I can connect to and log into the server just fine.  The session  
>>> works great
>>> as long as I am actively doing something in the shell.  However,  
>>> if I let it
>>> sit idle for (it seems) < 1 minute, the session seems to just lock  
>>> up.
>> Many consumer routers/DSL modems do not handle long running SSH
>> connections well.  They sometimes tend to kill the connection
>> prematurely.  You can experiment with the SSH options TCPKeepAlive,
>> and ServerAlive in the client to see if you can avoid it.  However
>> more often than not the problem is caused by the router itself.
>> --lonnie
> I've had pretty good success using these options in the sshd_config:
> 	ClientAliveInterval 60
> 	ClientAliveCountMax 3
> Frank

Turns out that I've traced my ssh hanging problems to my RVS4000  
router at the office.

In short, it's Intrusion Detection System gunk keeps thinking that my  
ssh connections are attempts to break in and rule the world, so it  
kills my connections.  There is no way to make an exception or  
variance in the firmware to allow my connections to work properly.

Additionally, it hangs on other types of perfectly legitimate traffic  
as well.

So, it has to go.

See my other post about what I'm looking for if you have any  
suggestions for a replacement router.


- Kimball

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