SSH - nimrody/knowledgebase GitHub Wiki

Using SSH

• ssh login without password

  ssh user@host "mkdir -p .ssh && cat >> .ssh/authorized_keys" < ~/.ssh/id_rsa.pub
  http://tychoish.com/rhizome/9-awesome-ssh-tricks/
  http://news.ycombinator.com/item?id=3011947
  brew install ssh-copy-id # on os x
  

• Remote (-R) port forwarding

  expose a local port to remote machine

  ssh -R *:2222:localhost:22 nimrody.com
  

  will forward all connections to 2222 on nimrody.com *r means all interfaces. otherwise default is localhost only) to localhost:22 (SSHd)

• Local port forwarding

  expose a remote port as local port (forward all connections to local port to the one on the remote machine) For example connect to remote SQL server as if it was local (assuming it blocks connections from outside except from localhost)

  Or expose JVM debug ports on a remote machine as local

  Can expose an inaccessible host on VPN if we can SSH into the gateway:

  local=localhost:1234 (or just 1234)
  remote=private_host:443 (private host not accessible from outside the private network)
  ssh -L ${local}:${remote} gateway-public-host
  

• Socks5 Proxy

  Tunnel all connection through gateway machine (then setup your browser to use socks on 127.0.0.1:8123)

  ssh -fNn -D 8123 gateway-hostname
  curl --socks5-hostname localhost:8123 some-host-we-cannot-access
  

  (the above will go through the gateway)

• Agent forwarding: ssh -A hostname forwards my private key to hostname so I can ssh from there

• SSH escape character

  recognized after newline default to ~

  ~? - help ~. - terminate connection ~C command line

• Proxy connection using another host

  Host tensera
    #ProxyCommand ssh nimrody.com nc localhost 22222
    ProxyCommand ssh nimrody.com -W localhost:22222
  

  (the above assumes nimrody.com has someone listing on port 22222)

• SSH information

• Setting up a certificate authority