How to access a remote machine via SSH from behind a proxy

PROXYsshterminal

I’m trying to connect to a Linux machine via SSH. The problem is that my Mac is in a different network, behind a proxy that routes HTTP and HTTPS through port 80.

How can I access the Linux machine via SSH from terminal?

Connecting with -vvv returns the following result:

OpenSSH_5.2p1, OpenSSL 0.9.8r 8 Feb 2011
debug1: Reading configuration data /etc/ssh_config
debug2: ssh_connect: needpriv 0
debug1: Connecting to _example.com_ [_ip_address_] port 22.
debug1: connect to address _ip_address_ port 22: Connection refused
ssh: connect to host _example.com_ port 22: Connection refused

Best Answer

You may need tunneling technique for accessing an HTTP proxy using SSH tunneling check this link: http://kimmo.suominen.com/docs/proxy-through-ssh/

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How to determine reason for SSH broken pipe

Check for local keep alive settings on your mac. These were mine...:

sysctl -a | grep tcp.keep
net.inet.tcp.keepidle: 3600
net.inet.tcp.keepintvl: 150
net.inet.tcp.keepinit: 75000
net.inet.tcp.keepcnt: 8

I needed to change the keepintvl setting to some higher value:

sudo sysctl -w net.inet.tcp.keepintvl=7500

Then the ssh "write failed: Broken pipe" error messages vanished.

VNC via SSH Problem

It looks to me like you're using the wrong remote IP address in your tunnel. You should be using -L 5901:127.0.0.1:5900 ....

It's important to realize that the destination IP for the tunnel is where the remote (server) computer forwards the connection to, so 127.0.0.1:5900 means it connects to port 5900 on the server itself.

It looks like you're using ssh -L 5901:PublicIPofServer:5900 ..., which makes the server try to connect to port 5900 on its own public IP. But that's actually the WAN IP of the router the server's behind, so unless that router forwards port 5900 to the private IP of the server (in which case you wouldn't need the SSH tunnel) AND the router supports NAT loopback (aka hairpin NAT), this won't work.

Best Answer

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