I am trying to use a SSH server as a gateway to connect to more than one internal servers. Internal in this context means that they are not accessible directly, they got no public IP assigned to them.
So the scenario should look like this (example with 2 servers, might be more) with the gateways public IP 123.456.789.45 the internal being 10.12.40.13
+--------+ +---------+ +----------+ | client |--> 2214/tcp --> | | --> 22/tcp --> | Server 1 | +--------+ | | +----------+ | Gateway | +--------+ | | +----------+ | client |--> 2215/tcp --> | | --> 22/tcp --> | Server 2 | +--------+ +---------+ +----------+
My first approach was to set them up from the gateway to the servers with something like
ssh -N -L 123.456.789.45:2214:127.0.0.1:22 tunnel-user@server1 ssh -N -L 123.456.789.45:2215:127.0.0.1:22 tunnel-user@server2
While that works I stumbled upon the problem of the tunnels not being too reliable, failing every here and there. The logical next step was trying to get
autossh running. And here I got a bunch of problems. The first tunnel can be established without problems using
autossh -M 20000 -f -N -L 123.456.789.45:2214:127.0.0.1:22 tunnel-user@server1
I can get access to server1 by outside connecting to the gateway at port 2214. However I can't get the second one up and running with autossh. Headbanging a couple of hours now I decided to try it vice versa. So:
The second approach was to set them up from the servers to the gateway. Again while the variant with pure ssh works using something like this ...
ssh -R 123.456.789.45:2214:127.0.0.1:22 tunnel-user@gateway # <- init from server 1 ssh -R 123.456.789.45:2215:127.0.0.1:22 tunnel-user@gateway # <- init from server 2
... using autossh fails.
autossh -M 20000 -f -R 123.456.789.45:2214:127.0.0.1:22 tunnel-user@gateway
The logfiles simply says nothing. Syslog at least comes up with
ssh exited prematurely with status 0; autossh exiting
Now does anyone know how to solve the
autossh issue on either approach? Is there something similar to
autossh that I can give a shot? Is there a way to maybe achieve something like a refresh on the pure ssh version mentioned above?
All involved servers are running the latest updates on Ubuntu 10.04 LTS and autossh 1.4b