{"id":713,"date":"2011-03-30T16:36:30","date_gmt":"2011-03-30T15:36:30","guid":{"rendered":"http:\/\/www.dotmana.com\/index.php\/?p=713"},"modified":"2011-03-30T16:36:30","modified_gmt":"2011-03-30T15:36:30","slug":"tunnel-ssh-through-proxy-web-with-dns","status":"publish","type":"post","link":"http:\/\/www.dotmana.com\/weblog\/2011\/03\/tunnel-ssh-through-proxy-web-with-dns\/","title":{"rendered":"Tunnel SSH through proxy web (with DNS !)"},"content":{"rendered":"

This is a little cookquide to setup a ssh tunnel through a proxy web. Your DNS queries will also be tunneled.<\/strong><\/p>\n

First step, you need a ssh server on a remote server.
\nConfigure it to listen to port 443 :<\/p>\n

file : \/etc\/ssh\/sshd_config
\nPort 22
\nPort 443<\/p><\/blockquote>\n

Then you need to install corkscrew (on your local machine) :<\/p>\n

sudo apt-get install corkscrew<\/p><\/blockquote>\n

Then create (or edit) your local ssh config file (~\/.ssh\/config) :<\/p>\n

Host ssh-proxy
\nHostName your-remote-ssh-server
\n# Local SSH Server port
\nPort 443
\n# Keep-Alive
\nKeepAlive yes
\nProtocolKeepAlives 60
\n# Use proxy with login\/passwd
\n# ProxyCommand \/usr\/bin\/corkscrew address-of-proxy 3128 %h %p \/home\/user\/.ssh\/proxy_auth
\n# Use proxy without authentication
\nProxyCommand \/usr\/bin\/corkscrew address-of-proxy 3128 %h %p<\/p><\/blockquote>\n

If your proxy need authentication, enable first ProxyCommand line and add in ~\/.ssh\/proxy_auth credentials for proxy :<\/p>\n

user:password<\/p><\/blockquote>\n

Then launch your ssh tunnel through the proxy<\/p>\n

ssh -D 9999\u00a0 user@ssh-proxy<\/p><\/blockquote>\n

From this point, you can use your application with proxy socks enabled to localhost:9999 and you can reach the web.<\/p>\n

if you just need to browse, you can directly forward your DNS queries through proxy socks with (in Firefox) :<\/p>\n

\n
  • about:config<\/li>\n
  • search string “dns”<\/li>\n
  • enable to “true” key “network.proxy.socks_remote_dns”<\/li>\n<\/blockquote>\n

    And now, how to send your DNS queries also through your ssh tunnel.<\/strong><\/p>\n

    Install socat tool on your remote server AND on your local machine :<\/p>\n

    sudo apt-get install socat<\/p><\/blockquote>\n

    On your remote server, launch socat to transform TCP request from 5353 to DNS UPD queries 53 (in this command, we use Google DNS) :<\/p>\n

    socat tcp4-listen:5353,reuseaddr,fork UDP:8.8.8.8:53<\/p><\/blockquote>\n

    On your local machine, launch socat to transform local DNS queries to TCP port 5353 (need to be launched as root, since we listen on port 53) :<\/p>\n

    sudo socat -T15 udp4-recvfrom:53,reuseaddr,fork tcp:localhost:5353<\/p><\/blockquote>\n

    Edit your \/etc\/resolv.conf file to add a “local DNS server” :<\/p>\n

    nameserver localhost<\/p><\/blockquote>\n

    And eventually, launch a a specific DNS tunnel over SSH :<\/p>\n

    ssh -N -L 5353:localhost:5353 user@your-remote-server<\/p><\/blockquote>\n

    You can ping real world \ud83d\ude09<\/p>\n

    To resume, once tools are installed, you need to launch (in this order) : <\/strong><\/p>\n

    First terminal :<\/p>\n