iankelling.org Git - vpn-setup/blob - vpn-mk-client-cert

   1 #!/bin/bash
   2 # Copyright (C) 2016 Ian Kelling
   3
   4 # Licensed under the Apache License, Version 2.0 (the "License");
   5 # you may not use this file except in compliance with the License.
   6 # You may obtain a copy of the License at
   7
   8 #     http://www.apache.org/licenses/LICENSE-2.0
   9
  10 # Unless required by applicable law or agreed to in writing, software
  11 # distributed under the License is distributed on an "AS IS" BASIS,
  12 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13 # See the License for the specific language governing permissions and
  14 # limitations under the License.
  15
  16 set -eE -o pipefail
  17 trap 'echo "$0:$LINENO:error: \"$BASH_COMMAND\" returned $?" >&2' ERR
  18
  19 [[ $EUID == 0 ]] || exec sudo -E "$BASH_SOURCE" "$@"
  20
  21 readonly this_file="$(readlink -f -- "${BASH_SOURCE[0]}")"; cd "${this_file%/*}"
  22
  23
  24 usage() {
  25   cat <<'EOF'
  26 usage: ${0##*/} VPN_SERVER_HOST
  27
  28 -b COMMON_NAME   By default, use $CLIENT_HOST or if it is not given,
  29                  $HOSTNAME. If the cert already exists on the server,
  30                  with the CLIENT_NAME name, we use the existing one. See
  31                  comment below if we ever want to check existing common
  32                  names. They must be unique per server, so you can use
  33                  $(uuidgen) if needed. You used to be able to create
  34                  multiple with the same name, but not connect at the
  35                  same time, but now, the generator keeps track, so you
  36                  can't generate.
  37
  38 -c CLIENT_HOST   Default is localhost. Else we ssh to root@CLIENT_HOST.
  39 -f               Force. Proceed even if cert already exists.
  40 -n CONFIG_NAME   default is client
  41 -o SERVER_CONFIG_NAME  Default is CONFIG_NAME
  42 -s SCRIPT_PATH   Use custom up/down script at SCRIPT_PATH. If client host is
  43                  not localhost, the script is copied to it. The default
  44                  script used to be /etc/openvpn/update-resolv-conf, but now
  45                  that systemd-resolved is becoming popular, there is no default.
  46
  47 Generate a client cert and config and install it on locally or on
  48 CLIENT_HOST if given.  Uses default config options, and expects be able
  49 to ssh to VPN_SERVER_HOST and CLIENT_HOST as root, or if CLIENT_HOST is
  50 localhost, just to sudo this script as root.
  51
  52
  53
  54
  55 Note: Uses GNU getopt options parsing style
  56 EOF
  57   exit ${1:-0}
  58 }
  59
  60 # to get the common name
  61 # cn=$(s openssl x509 -noout -nameopt multiline -subject \
  62   #        -in /etc/openvpn/client/mail.crt | \
  63   #          sed -rn 's/^\s*commonName\s*=\s*(.*)/\1/p')
  64
  65
  66 ####### begin command line parsing and checking ##############
  67
  68 shell="bash -c"
  69 name=client
  70 client_host=$CLIENT_HOST
  71 force=false
  72
  73 temp=$(getopt -l help hb:c:fn:o:s: "$@") || usage 1
  74 eval set -- "$temp"
  75 while true; do
  76   case $1 in
  77     -b) common_name="$2"; shift 2 ;;
  78     -c) client_host=$2; shell="ssh root@$client_host"; shift 2 ;;
  79     -f) force=true; shift ;;
  80     -n) name="$2"; shift 2 ;;
  81     -o) server_name="$2"; shift 2 ;;
  82     -s) script="$2"; shift 2 ;;
  83     -h|--help) usage ;;
  84     --) shift; break ;;
  85     *) echo "$0: Internal error! unexpected args: $*" ; exit 1 ;;
  86   esac
  87 done
  88
  89 if [[ ! $server_name ]]; then
  90   server_name="$name"
  91 fi
  92
  93 if [[ ! $common_name ]]; then
  94   if [[ $client_host ]]; then
  95     common_name=$client_host
  96   else
  97     common_name=$HOSTNAME
  98   fi
  99 fi
 100
 101 host=$1
 102 [[ $host ]] || usage 1
 103
 104 ####### end command line parsing and checking ##############
 105
 106
 107 f=/etc/openvpn/client/$name.crt
 108
 109 cert_to_test=$f
 110 if [[ $client_host ]]; then
 111   cert_to_test=$(mktemp)
 112   ssh root@$client_host cat $f 2>/dev/null >$cert_to_test ||:
 113 fi
 114 if ! $force && openssl x509 -checkend $(( 60 * 60 * 24 * 30 )) -noout -in $cert_to_test &>/dev/null; then
 115   echo "$0: cert already exists. exiting early"
 116   exit 0
 117 fi
 118
 119
 120 # bash or else we get motd spam. note sleep 2, sleep 1 failed.
 121 $shell '[[ -e /etc/openvpn ]] || apt install openvpn'
 122 if ! ssh root@$host bash -s -- $server_name $common_name < client-cert-helper \
 123     |  $shell 'id -u | grep -xF 0 || s=sudo; $s tar xzv -C /etc/openvpn/client'; then
 124   echo ssh root@$host cat /tmp/vpn-mk-client-cert.log:
 125   ssh root@$host cat /tmp/vpn-mk-client-cert.log
 126   echo EOF for root@$host:/tmp/vpn-mk-client-cert.log
 127   exit 1
 128 fi
 129
 130 port=$(echo '/^port/ {print $2}' | ssh root@$host awk -f - /etc/openvpn/server/$name.conf | tail -n1)
 131
 132
 133 if ! $shell "test -s $f"; then
 134   # if common name is not unique, you get empty file. and if we didn't silence
 135   # build-key, you'd see an error "TXT_DB error number 2"
 136   echo "$0: error: $f is empty or otherwise bad. is this common name unique?"
 137   exit 1
 138 fi
 139
 140 $shell "dd of=/etc/openvpn/client/$name.conf" <<EOF
 141 # From example config, from debian stretch to buster
 142 client
 143 dev tun
 144 proto udp
 145 remote $host $port
 146 resolv-retry infinite
 147 nobind
 148 persist-key
 149 persist-tun
 150 ca ca-$name.crt
 151 cert $name.crt
 152 key $name.key
 153 # disabled for better performance
 154 #comp-lzo
 155 verb 3
 156
 157 # matching server config
 158 cipher AES-256-CBC
 159
 160 # example config has the commented line, but this other thing looks stronger,
 161 # and I've seen it in a vpn provider I trust
 162 # ns-cert-type server
 163 remote-cert-tls server
 164
 165 # more resilient when running as nonroot
 166 persist-key
 167
 168 # See comments in server side configuration.
 169 # The minimum of the client & server config is what is used by openvpn.
 170 reneg-sec 432000
 171
 172 tls-auth ta-$name.key 1
 173 EOF
 174
 175 if [[ $script ]]; then
 176   $shell "tee -a /etc/openvpn/client/$name.conf" <<EOF
 177 script-security 2
 178 up "$script"
 179 down "$script"
 180 EOF
 181
 182   if [[ $client_host && $script ]]; then
 183     $shell "dd of=$script" <$script
 184     $shell "chmod +x $script"
 185   fi
 186 fi
 187
 188 $shell 'cd /etc/openvpn; for f in client/*; do ln -sf $f .; done'