remote port forwarding unstable

[Peter Lambrechtsen]

Perhaps it is something wrong with your ssh client.

I have had remote ssh port forwarding sessions open for weeks and in  
frequent use when using putty on the client and openssh 5.1 on the  
server.

I have also had remote upon remote sessions going, which works, albiet  
a little slowly. IE

Session1 client -> server1 -ssh -R 1080:server2:1080 -> server2
And
Session2 client -putty remote port forwarding 1080 on server1

This allows me to access a web mgmt port for an app on server 2 which  
is sitting behind two firewalls that do not allowed to have web  
traffic in there.

Very round about way of doing things. But it works

Thanks

Peter

On 20/10/2009, at 1:31 AM, Adriana Rodean <adrya1984 at gmail.com> wrote:

> Hi,
>
> I'm not sure if this is a bug or not, maybe someone noticed it also...
>
> I always do a remote port forwarding with openssh on 1026 port let's
> say ( ssh -R 1026:localhost:55555 ). Most times the port is opened on
> remote machine. But sometimes i notice that ssh can't do remote port
> forwarding to that port 1026. I looked on the remote machine (netstat
> -an) and no one is using that port, so the port is free.
> Only way to fix this is do a remote port forwarding to another port
> lets say 1056, successfully done, then try again and do it for 1026,
> this time remote port forwarding successfully works... Sometimes it
> works if i try again with 1026, but other times i need to open another
> port then try again with 1026 port...
>
> What can cause this instability to remote port forwarding?
> Is there another command than "netstat -an" to see if that port is
> really free or something is using it?
> If is a bug can it be fixed?
>
> I use version of OpenSSH 5.1p1 on remote machine and the client is
> OpenSSH for Windows 3.8.1p1
>
> Thanks in advance,
> Adriana
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