====== SSH ====== ==== Converting SSH2 Keys ==== From ssh2 to openssh


ssh-keygen -i -f id_dsa.pub > id_dsa_open.pub

From OpenSSH to ssh2


ssh-keygen -e -f id_dsa.pub > id_dsa_ssh2.pub

==== SCP Speed UP ==== To increase speed on transfer you can force cipher to arcfour.\\ You can use same mechanism with rsync when you use ssh encapsulation. \\


scp -c arcfour


rsync -av -e "ssh -c arcfour -l "

NOTE: THis reduce your security though ==== SSH Tunnels ==== === Forward Tunnel === It is used when you want to forward local port to remote port over SSH.


ssh -f -N -L 5445:localhost:5432 root@

=== Reverse Tunnel === It is used when you want to forward Remote Port to Local Port.\\ Usually used to allow access other way around.


ssh -f -N -R 5445:localhost:5432 root@

==== SSH Agent automation ==== Undefine existing value and define new value in session.\\ This also keep the value same since nothing is changing.


    unsetenv SSH_AUTH_SOCK
    setenv SSH_AUTH_SOCK $HOME/.screen/ssh-auth-sock.$USERNAME

Each call of screen command will overwrite the existing symlink.


    _ssh_auth_save() {
            ln -sf "$SSH_AUTH_SOCK" "$HOME/.screen/ssh-auth-sock.$USERNAME"
    }
    alias screen='_ssh_auth_save ; screen'

Now add key to your session with "ssh-add".\\ That should do it. ==== Tips & Tricks ==== == Show fingerprint of key == You can use -v to print random ASCII Image


# Using -E can specify MD5 has which mostly require to compare
ssh-keygen -lf .ssh/OLD/id_rsa.pub.old


ssh-keygen -l -F ip.k2patel.in

It will print for all public key in single file if there is multiple key in it.\\ Also, it is usefull in identifying MITM Attack by comparing against your known host.\\ == Print fingerprint on login == You can enabled printing of server key by setting following variable.\\ you can setup on any of following file /etc/ssh/ssh_config OR .ssh/config


VisualHostKey yes

== Run Command from file Remotely == Place all your command in xyz file. And run as follows


ssh -l k2patel nice.k2patel.in "`cat xzy`"

== Comment on public key == You can control comment on public key during generation using following command.


ssh-keygen -t rsa -C "k2patel rsync to remote server xyz" -f .ssh/remote_xyz

== Temporarily disable ssh key forwarding == This will disable key forwarding, while login with the key.


ssh yahoo.com -i .ssh/id_ed25519 -o IdentitiesOnly=yes -F /dev/null -l ketan