SSH Config based on ssh command with port forwarding

fingerprints

4/17/24, 6:31 PM

I'm trying to convert the following SSH command on a SSH File entry.

My command is as follows:

ssh -i identity-file.pem -L 20000:internal-host.com:8080 [email protected] -N

An this is the current SSH file

Host remote-host-tunnel
  IdentitiesOnly yes
  HostName remote-host.com
  User user
  PubKeyAuthentication yes
  IdentityFile ~/.ssh/identity-file.pem
  ServerAliveInterval 30

Host internal-host-forwarding
  LocalForward 20000 internal-host.com:8080
  Hostname internal-host.com
  ProxyCommand ssh remote-host-tunnel nc %h %p

I'm able to reach the tunnel as folows:

ssh remote-host-tunnel

Everything up until this point works fine

But then, when I want to access the internal-host it's not working

ssh internal-host-forwarding -N

The connection does not get established

Ncat: Connection timed out.

kex_exchange_identification: Connection closed by remote host

Connection closed by UNKNOWN port 65535

195

1 + 0

ssh

port-forwarding

ssh-tunnel

Score:2

Server

Saxtheowl

4/17/24, 7:56 PM

You are trying to to use the ProxyCommand with netcat to establish a connection to the internal host, but that is not necessary for port forwarding, just combine the configurations of both hosts into a single entry like this in your ssh config file:

Host remote-host-tunnel
  IdentitiesOnly yes
  HostName remote-host.com
  User user
  PubKeyAuthentication yes
  IdentityFile ~/.ssh/identity-file.pem
  ServerAliveInterval 30
  LocalForward 20000 internal-host.com:8080

Now you can just connect to the remote-host-tunnel

ssh remote-host-tunnel -N

edit: You can also create multiple entries for each internal host like the example below

Host remote-host-tunnel
  IdentitiesOnly yes
  HostName remote-host.com
  User user
  PubKeyAuthentication yes
  IdentityFile ~/.ssh/identity-file.pem
  ServerAliveInterval 30

Host internal-host-forwarding-1
  Hostname localhost
  Port 20000
  ProxyJump remote-host-tunnel
  LocalForward 20000 internal-host1.com:8080

Host internal-host-forwarding-2
  Hostname localhost
  Port 20001
  ProxyJump remote-host-tunnel
  LocalForward 20001 internal-host2.com:8080

and if you want to connect to internal-host-forwarding-1 do ssh internal-host-forwarding-1 -N

+ 2

fingerprints

4/17/24, 8:18 PM

Thank you for your answer. This was my workaround as well, but I have multiple tunnels that were suppose to connect to different `internal-hosts` that need to go all trough the same `remote-host` . That's why I was trying to keep them separated

Saxtheowl

4/17/24, 8:41 PM

You welcome, I updated my answer

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