$ cat ~/.ssh/config
ServerAliveInterval 60
SendEnv NO
TCPKeepAlive yes
ServerAliveInterval=15
ServerAliveCountMax=6
Compression=yes
ForwardAgent=yes
#GSSAPIAuthentication no
ControlMaster auto
ControlPath /tmp/ssh_mux_%h_%p_%r
Host *
  StrictHostKeyChecking no

SSH_ENV="$HOME/.ssh/environment"
function start_agent {
     #echo "Initialising new SSH agent..."
     /usr/bin/ssh-agent | sed 's/^echo/#echo/' > "${SSH_ENV}"
     #echo succeeded
     chmod 600 "${SSH_ENV}"
     . "${SSH_ENV}" > /dev/null
     /usr/bin/ssh-add;
}
if [ -f "${SSH_ENV}" ]; then
     . "${SSH_ENV}" > /dev/null
     ps -ef | grep ${SSH_AGENT_PID} | grep ssh-agent$ > /dev/null || {
         start_agent;
     }
else
     start_agent;
fi

SSH_ENV="$HOME/.ssh/environment"
function start_agent {
     #echo "Initialising new SSH agent..."
     /usr/bin/ssh-agent | sed 's/^echo/#echo/' > "${SSH_ENV}"
     #echo succeeded
     chmod 600 "${SSH_ENV}"
     . "${SSH_ENV}" > /dev/null
     /usr/bin/ssh-add;
}
if [ -f "${SSH_ENV}" ]
then
     . "${SSH_ENV}" > /dev/null
     ps -ef | grep ${SSH_AGENT_PID} | grep ssh-agent$ > /dev/null
     if [ ! "$?" = "0" ]; then
         start_agent;
     fi
else
     start_agent;
fi