CODEWITHSUNDEEP
sshportportforwardingtunnel
zed2zed
zed2zed

Reputation: 1

SSH Remote Tunnel port

I have 3 computers 2 Linux and 1 Windows. Windows PC and Linux server (A) are on the same network (1). The linux server (B) is on another network (2).

I want to make an SSH tunnel between the 2 linux servers to allow the Windows PC to access an HTTP page of the Linux server (B), which is therefore on another network.

With this command on the linux server (A) the tunnel works fine but only locally in linux.

ssh -R 8080:localhost:80 linuxa.internet.com

But from Windows PC I cannot access port 8080 on linux (A). http://linuxa.local:8080 does not work.

So I tried these two commands to open access to my PC but it doesn't work either.

ssh -R 0.0.0.0:8080:localhost:80 linuxa.internet.com
ssh -R ipwindows:8080:localhost:80 linuxa.internet.com

Can you help me ?

Thank you

Upvotes: 0

Views: 1377

Answers (2)

zed2zed
zed2zed

Reputation: 1

Thank you for your answer but I don't think I have a firewall installed

systemctl status firewalld

return

Unit firewalld.service could not be found.

and

firewall-cmd --add-port 8080/tcp

-bash: firewall-cmd: command not found

Upvotes: 0

Alex Baranowski
Alex Baranowski

Reputation: 1084

From a comment, I conclude that you might have problem with the firewall. Suppose you can reach the tunnel from the host that is "proxy" (with curl,wget,ncat etc. on localhost). You should check what block traffic. In most cases, it is a firewall. Depending on your Linux distro you might have different backends and frontends for a firewall. If you have firewall-cmd command installed it's very likely that firewalld is one.

But before blaming the firewall, you should check if a port is open/closed. I prefer netcat:

HOST_THAT_SHOULD_HAVE_OPEN_PORT #  nc -l 8080

HOST_THAT_SHOULD_BE_ABLE_TO_CONNECT # nc HOST_THAT_SHOULD_HAVE_OPEN_PORT 8080

If there is no connection or connection is refused, it's extremely likely that the firewall is the problem.

You can check if firewalld is running with systemctl:

# systemctl status firewalld
● firewalld.service - firewalld - dynamic firewall daemon
     Loaded: loaded (/usr/lib/systemd/system/firewalld.service; enabled; vendor preset: enabled)
     Active: active (running) since Mon 2021-02-08 21:42:29 CET; 13h ago

Then you might add traffic on port 8080:

# firewall-cmd --add-port 8080/tcp
success

It will temporarily open network traffic on 8080. Then you should be able to use port 8080 and your ssh tunnel.

Upvotes: 0

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