src/monkeysphere-ssh-proxycommand



#!/bin/sh -e

# monkeysphere-ssh-proxycommand: MonkeySphere ssh ProxyCommand hook
#
# The monkeysphere scripts are written by:
# Jameson Rollins <jrollins@fifthhorseman.net>
#
# They are Copyright 2008, and are all released under the GPL, version 3
# or later.

# This is meant to be run as an ssh ProxyCommand to initiate a
# monkeysphere known_hosts update before an ssh connection to host is
# established.  Can be added to ~/.ssh/config as follows:
#  ProxyCommand monkeysphere-ssh-proxycommand %h %p

usage() {
cat <<EOF >&2
usage: ssh -o ProxyCommand="$(basename $0) %h %p" ...
EOF
}

log() {
    echo "$@" >&2
}

if [ "$1" = '--no-connect' ] ; then
    NO_CONNECT='true'
    shift 1
fi

HOST="$1"
PORT="$2"

if [ -z "$HOST" ] ; then
    log "host must be specified."
    usage
    exit 1
fi
if [ -z "$PORT" ] ; then
    log "port must be specified."
    usage
    exit 1
fi

# set the host URI
URI="ssh://${HOST}"
if [ "$PORT" != '22' ] ; then
    URI="${URI}:$PORT"
fi

# if the host is in the gpg keyring...
if gpg --list-key ="${URI}" 2>&1 >/dev/null ; then
    # do not check the keyserver
    CHECK_KEYSERVER="false"
# if the host is NOT in the keyring...
else
    # if the host key is found in the known_hosts file...
    # FIXME: this only works for default known_hosts location
    hostKey=$(ssh-keygen -F "$HOST")
    if [ "$hostKey" ] ; then
    # if the check keyserver variable is NOT set to true...
    if  [ "$CHECK_KEYSERVER" != 'true' ] ; then
        # schedule a keyserver check for host at a later time
        echo "monkeysphere update-known_hosts $HOST" | at noon
    fi
    # if the host key is not found in the known_hosts file...
    else
    # check the keyserver
    CHECK_KEYSERVER="true"
    fi
fi
export CHECK_KEYSERVER

# update the known_hosts file for the host
monkeysphere update-known_hosts "$HOST"

# exec a netcat passthrough to host for the ssh connection
if [ -z "$NO_CONNECT" ] ; then
    exec nc "$HOST" "$PORT"
fi