youatwork@officepc$ autossh -R 12345:localhost:22 notroot@serverpc
Later:
you@homepc$ autossh -L 23456:localhost:12345 notroot@serverpc
you@homepc$ ssh youatwork@localhost -p 23456
What you could do is this: in step 1 forward a remote port from the office PC to the server (12345
is used as an example, any port >1024 should do). Now connecting to 12345 on the server should connect you to port 22 on officepc.
In step 2, forward the port 23456 from your home machine to 12345 on the server (whence it gets forwarded to officepc:22, as set up in step 1)
In step 3, you connect to the local port 23456 with your office PC login. This is forwarded by step 2 to port 12345 on your server, and by step 1 to your office PC.
Note that I'm using autossh for the forwardings, as it's a ssh wrapper which automatically reconnects the tunnel should it be disconnected; however normal ssh would work as well, as long as the connection doesn't drop.
There is a possible vulnerability: anyone who can connect to localhost:12345 on serverpc can now connect to officepc:22, and try to hack into it. (Note that if you're running a SSH server, you should anyway secure it above the basic protections which are on by default; I recommend at least disabling root login and disabling password authentication - see e.g. this)
Edit: I have verified this with the same config, and it works. GatewayPorts no
only affects the ports that are open to the world at large, not local tunnels. This is what the forwarded ports are:
homepc:
outgoing ssh to serverpc:22
listening localhost:23456 forwarded through ssh tunnel
serverpc:
listening ssh at *:22
incoming localhost ssh tunnel (from homepc) forwarded to localhost:12345
listening localhost ssh tunnel (from officepc) forwarded from localhost:12345
officepc:
outgoing ssh to serverpc:22
incoming localhost through ssh tunnel (from serverpc) forwarded to localhost:22
So, as far as the network stack is concerned, it's all local traffic on the respective loopback interfaces (plus ssh connections to serverpc); therefore, GatewayPorts
is not checked at all.
There is, however, the directive AllowTcpForwarding
: if that is no
, this setup will fail as no forwarding is allowed at all, not even across the loopback interface.
Caveats:
if using autossh and recent ssh, you may want to use ssh's ServerAliveInterval
and ServerAliveCountMax
for keeping the tunnel up. Autossh has a built-in check, but apparently it has some issues on Fedora. -M0
disables that, and -oServerAliveInterval=20 -oServerAliveCountMax=3
checks if the connection is up - tries each 20 sec, if it fails 3x in a row, stops ssh (and autossh makes a new one):
autossh -M0 -R 12345:localhost:22 -oServerAliveInterval=20 -oServerAliveCountMax=3 notroot@serverpc
autossh -M0 -L 23456:localhost:12345 -oServerAliveInterval=20 -oServerAliveCountMax=3 notroot@serverpc
it might be useful to restart ssh tunnel if the forward fails, using -oExitOnForwardFailure=yes
- if the port is already bound, you might get a working SSH connection, but no forwarded tunnel.
using ~/.ssh/config
for the options (and ports) is advisable, else the command lines get too verbose. For example:
Host fwdserverpc
Hostname serverpc
User notroot
ServerAliveInterval 20
ServerAliveCountMax 3
ExitOnForwardFailure yes
LocalForward 23456 localhost:12345
Then you can use just the server alias:
autossh -M0 fwdserverpc
Well, if you connect PC1 directly to the ISP it works. If you put the router in between it does not work. You have done the correct error searching process and found that the router is the problem.
Why is it the problem? It sounds like it is choking on your packets. The internet speed is probably higher than what the router can manage. The D-Link D300 is in the low-budget spectrum of routers, and this is not an uncommon problem.
The games that work perhaps simply do not generate as much data, or have more fault tolerance regarding latency before skipping.
Best Answer
I would like to clarify Brian:s answer about Hamachi, with a Linux focus.
First install it:
Then go to the hamachi page and create a new mash network, remember the "network-number" since the do-login needs it.
Back to the command line
Then back to the webpage again and allow the clients to be on this network. (maybe need to have the client to login again)
Then check what pc is on the network:
Now you can grab that ip-number and ssh directly regardless if there is a NAT in the way!
/Have fun