Hi All,

I am running an application over telnet interface on port say 5566
So I generally connect telnet <hostname> 5566.

How to connect to the application via ssh (using ssh portforwarding.)

Thanks and Regards,
Jc

Jc wrote:
> Hi All,
>
> I am running an application over telnet interface on port say 5566
> So I generally connect telnet <hostname> 5566.
>
> How to connect to the application via ssh (using ssh portforwarding.)
>
> Thanks and Regards,
> Jc
>

ssh -L 5566:localhost:5566 userid@remotehost

telnet localhost 5566

Hi,
Thanks. It works.
But what happens is it directly logged into the remotehost which I
don't want. I want the user to get only the info through the port 5566
(ssh).
Any way?
Thanks in advance,
Jc
Chuck wrote:
> Jc wrote:
> > Hi All,
> >
> > I am running an application over telnet interface on port say 5566
> > So I generally connect telnet <hostname> 5566.
> >
> > How to connect to the application via ssh (using ssh portforwarding.)
> >
> > Thanks and Regards,
> > Jc
> >
>
> ssh -L 5566:localhost:5566 userid@remotehost
>
> telnet localhost 5566

On 9 Jan 2007 23:38:46 -0800
"Jc" <ramschitra@gmail.com> wrote:

> Hi,
> Thanks. It works.
> But what happens is it directly logged into the remotehost which I
> don't want. I want the user to get only the info through the port 5566
> (ssh).
> Any way?

It's a bit unclear what exactly you're looking for. If you want to
setup a tunnel between two systems and allow a other systems to use
that tunnel to connect, then use the -g option while forwarding. If you
instead want to use the remote host as a forwarder for the traffic into
a network it can access, then use ssh -L 5566:THIRDHOST:5566 REMOTEHOST
and then telnet localhost 5566 will work for you.

Doug

--
For UNIX, Linux and security articles
visit http://SecurityBulletins.com/

Hi,

I don't want the user to login into my host instead I want the user to
connect only the specific port. But what happens is, if I execute the
port forwarding command, the user was able to login to my host.
Hoe is can be avided.

Thanks and Regards,
Jeyachitra.
Doug Spencer wrote:
> On 9 Jan 2007 23:38:46 -0800
> "Jc" <ramschitra@gmail.com> wrote:
>
> > Hi,
> > Thanks. It works.
> > But what happens is it directly logged into the remotehost which I
> > don't want. I want the user to get only the info through the port 5566
> > (ssh).
> > Any way?
>
> It's a bit unclear what exactly you're looking for. If you want to
> setup a tunnel between two systems and allow a other systems to use
> that tunnel to connect, then use the -g option while forwarding. If you
> instead want to use the remote host as a forwarder for the traffic into
> a network it can access, then use ssh -L 5566:THIRDHOST:5566 REMOTEHOST
> and then telnet localhost 5566 will work for you.
>
> Doug
>
> --
> For UNIX, Linux and security articles
> visit http://SecurityBulletins.com/

On 2007-01-18, Jc <ramschitra@gmail.com> wrote:
> I don't want the user to login into my host instead I want the user to
> connect only the specific port. But what happens is, if I execute the
> port forwarding command, the user was able to login to my host.
> Hoe is can be avided.

If you're using OpenSSH you can set the user's shell to, eg, /bin/true.
(You will probably have to add /bin/true to /etc/shells too). The user
will need to specify -N (or its equivalent in their client) to prevent
the client from requesting a shell. This will work only with the SSHv2
protocol.

Another alternative is to make the user's shell to be a shell script
that does something like "exec sleep 300". This will work with both
versions of the ssh protocol but will leave a bunch of sleep processes
running for a while.

As far as restricting the users to a specific port, older versions of
OpenSSH could only do that if you were using pubkey authentication.
Newer versions (>=4.4) have a PermitOpen directive for this purpose.

--
Darren Tucker (dtucker at zip.com.au)
GPG key 8FF4FA69 / D9A3 86E9 7EEE AF4B B2D4 37C9 C982 80C7 8FF4 FA69
Good judgement comes with experience. Unfortunately, the experience
usually comes from bad judgement.