TMPFILE=$(mktemp)

# cleanup old agent-sockets
if [ -r "${HOME}/.ssh-agent-forwarding" ]; then
    cut -d" " -f2 "${HOME}/.ssh-agent-forwarding" | \
	xargs ls -a 2>/dev/null | \
	grep -f - "${HOME}/.ssh-agent-forwarding" | \
	sort -n > "${TMPFILE}"
    
    mv "${TMPFILE}" "${HOME}/.ssh-agent-forwarding"
fi

# if this login is via ssh and ssh-agent is forwarded
if [ -n "$SSH_AUTH_SOCK" -a -n "$SSH_CLIENT" ]; then

    # add current socket
    echo "$(date +%s) $SSH_AUTH_SOCK $SSH_CLIENT" >> "${HOME}/.ssh-agent-forwarding"

    # remove old symlink
    if [[ -L "${HOME}/.ssh-agent-forwarded-sock" ]]; then
	rm -f "${HOME}/.ssh-agent-forwarded-sock"
    fi

    # create static symlink to socket
    if [[ ! -e "${HOME}/.ssh-agent-forwarded-sock" ]]; then
	ln -sf "$SSH_AUTH_SOCK" "${HOME}/.ssh-agent-forwarded-sock"
    else
	echo "Warning: ${HOME}/.ssh-agent-forwarded-sock exists and is not a symlink!"
    fi
fi

SSH_AUTH_SOCK="${HOME}/.ssh-agent-forwarded-sock"
export SSH_AUTH_SOCK