iankelling.org Git - distro-setup/blob - dynamic-ip-update

   1 #!/bin/bash
   2 # I, Ian Kelling, follow the GNU license recommendations at
   3 # https://www.gnu.org/licenses/license-recommendations.en.html. They
   4 # recommend that small programs, < 300 lines, be licensed under the
   5 # Apache License 2.0. This file contains or is part of one or more small
   6 # programs. If a small program grows beyond 300 lines, I plan to switch
   7 # its license to GPL.
   8
   9 # Copyright 2024 Ian Kelling
  10
  11 # Licensed under the Apache License, Version 2.0 (the "License");
  12 # you may not use this file except in compliance with the License.
  13 # You may obtain a copy of the License at
  14
  15 #     http://www.apache.org/licenses/LICENSE-2.0
  16
  17 # Unless required by applicable law or agreed to in writing, software
  18 # distributed under the License is distributed on an "AS IS" BASIS,
  19 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  20 # See the License for the specific language governing permissions and
  21 # limitations under the License.
  22
  23
  24 set -e; . /usr/local/lib/bash-bear; set +e
  25 [[ $EUID == 0 ]] || exec sudo -E "${BASH_SOURCE[0]}" "$@"
  26
  27 this_file="$(readlink -f -- "${BASH_SOURCE[0]}")"
  28 readonly this_file
  29 this_dir="${this_file%/*}"
  30 readonly this_dir
  31 cd "$this_dir"
  32
  33 usage() {
  34   cat <<EOF
  35 Usage: ${0##*/} [-f]
  36 Update ip in remote nameserver.
  37
  38 -f         Force update even if ip hasn't changed.
  39 -h|--help  Print help and exit.
  40
  41 Note: Uses util-linux getopt option parsing: spaces between args and
  42 options, short options can be combined, options before args.
  43 EOF
  44   exit $1
  45 }
  46
  47 ##### begin command line parsing ########
  48
  49 # ensure we can handle args with spaces or empty.
  50 ret=0; getopt -T || ret=$?
  51 [[ $ret == 4 ]] || { echo "Install util-linux for enhanced getopt" >&2; exit 1; }
  52
  53 force=false # default
  54 temp=$(getopt -l help hf "$@") || usage 1
  55 eval set -- "$temp"
  56 while true; do
  57   case $1 in
  58     -f) force=true ;;
  59     --) shift; break ;;
  60     *) echo "$0: unexpected args: $*" >&2 ; usage 1 ;;
  61   esac
  62   shift
  63 done
  64
  65 ##### end command line parsing ########
  66
  67 main() {
  68
  69   fqdn=$(hostname -f)
  70   domaintmp=${fqdn#*.}
  71   hostnametmp=${fqdn%%.*}
  72   # i for internet
  73   fqdn=${hostnametmp}i.${domaintmp}
  74
  75   up4=false
  76
  77   if ! tmp=$(ip -4 route get 85.119.83.50 2>/dev/null); then
  78     # our internet is down
  79     if [[ $INVOCATION_ID ]]; then
  80       return 0
  81     else
  82       echo $0: failed to get route, giving up
  83       exit 0
  84     fi
  85   fi
  86   read -r _ _  gateway _ ifdev _ <<<"$tmp"
  87
  88   case $gateway in
  89     10.2.0.1)
  90       dyndomain=b8.nz
  91       dynhost=i.b8.nz
  92       ;;
  93     *)
  94       return 0
  95       ;;
  96   esac
  97
  98   # We check if we are at home by testing gateway ssh
  99   # fingerprint. However, if we found in the past that we are, I dont
 100   # like to spam its logs with ssh login attempts, so just check if our
 101   # gateway interface has an increasing amount of packets sent +
 102   # received from last time.
 103   athome=false
 104   if [[ -s /dev/shm/dynamic-ip-update-state ]]; then
 105     oldbytes=$(cat /dev/shm/dynamic-ip-update-state)
 106     newbytes=$(awk '$1 == "'$ifdev':" {print $2 + $10}' /proc/net/dev)
 107     if [[ $oldbytes == [1-9]* ]] && (( newbytes >= oldbytes )); then
 108       athome=true
 109       printf "%s\n" "$newbytes" >/dev/shm/dynamic-ip-update-state
 110     fi
 111   fi
 112   if ! $athome && timeout -s 9 5 ssh-keyscan -p 2220 -t rsa $gateway 2>/dev/null | grep -qFx "[$gateway]:2220 ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQCH+/h1dGEfKEusBblndU2e6QT4wLCm5+yqr/sqh/0X9YfjR7BfWWm8nNmuP55cYc+Wuf5ljB1H1acXEcsl1y8e0j3agHfF0V74FE1N1zz5nn2Ep8NHnmqgEhza38ZxMPh+4p3X7zklEKU7+3SzybKBi8sg0wLzlS2LM0JaUN80zR2sK11Kye3dURUXPk78u5wodOkgcEYRwSYaDMJlUzWP+poRXIDJwFaMQnwmxbl/c84yOyaU0x/d6hFwoRscWecihX+vvBNeSyxR4xr2HDOyUWwJkctyAgt2p7w3tfkXOKcCRzTAjGVIMQLTvo0sG/yJbcyHoEFdFybCsgDvfyYn"; then
 113     athome=true
 114     awk '$1 == "'$ifdev':" {print $2 + $10}' /proc/net/dev > /dev/shm/dynamic-ip-update-state
 115   fi
 116
 117
 118   if $athome; then
 119     if ! cur4="$(dig +short $dynhost @iankelling.org | tail -1)"; then
 120       if [[ ! $INVOCATION_ID ]]; then
 121         echo "$0: dig failed. internet looks down. giving up"
 122       fi
 123       return 0
 124     fi
 125     if ip4=$(curl --connect-timeout 10 -s4 https://iankelling.org/cgi/pubip); then
 126       if $force || [[ $cur4 && $ip4 && $cur4 != "$ip4" ]]; then
 127         up4=true # update ipv4
 128       fi
 129     fi
 130   fi
 131
 132   # may not be set yet so allow fail
 133   cur6="$(host -4 -t aaaa $fqdn iankelling.org | sed -rn 's/.*has IPv6 address (.*)/\1/p;T;q')" ||:
 134
 135   up6=false
 136
 137   out6=$(curl --connect-timeout 10 -s6 https://iankelling.org/cgi/pubip) ||: # failure allowed if we have no ipv6
 138
 139   if [[ $out6 ]]; then
 140     dev=$(ip -o a show to $out6 | awk '{print $2}')
 141     # we use slaac with privacy extension, so get our less private more permanent address
 142     mac=$(cat /sys/class/net/$dev/address)
 143
 144     IFS=: read -ra f <<<$mac; set -- ${f[@]}
 145     ip6=${out6%:*:*:*:*}:$(printf %x $((0x$1 + 2)))$2:$3'ff:fe'$4:$5$6
 146     # in case we aren't using slaac
 147     if ! ip a | grep "^ *inet6 $ip6/" &>/dev/null; then
 148       ip6=$out6
 149     fi
 150   fi
 151
 152   if $force || [[ $cur6 != "$ip6" ]]; then
 153     up6=true
 154   fi
 155
 156   # if we failed to get our ipv6 addr, we probably have ipv6
 157   # connectivity problem.
 158   if [[ ! $ip6 ]]; then
 159     ip_arg=-4
 160   fi
 161
 162   if ! $up4 && ! $up6; then
 163     return 0
 164   fi
 165
 166   # note, a simpler way to do this would be to ssh and use
 167   # "${SSH_CLIENT%% *}
 168   # to update bind if needed.
 169
 170   tmpf=$(mktemp)
 171   cat >>$tmpf <<EOF
 172 server iankelling.org
 173 zone b8.nz
 174 EOF
 175
 176   if $up4; then
 177     cat >>$tmpf <<EOF
 178 update delete $dynhost. A
 179 update add $dynhost. 300 A $ip4
 180 update delete $dyndomain. A
 181 update add $dyndomain. 300 A $ip4
 182 EOF
 183   fi
 184
 185   if $up6; then
 186     if [[ $ip6 ]]; then
 187       cat >>$tmpf <<EOF
 188 update delete $fqdn. AAAA
 189 update add $fqdn. 60 AAAA $ip6
 190 EOF
 191     else
 192       cat >>$tmpf <<EOF
 193 update delete $fqdn. AAAA
 194 EOF
 195     fi
 196   fi
 197
 198   cat >>$tmpf <<EOF
 199 show
 200 send
 201 answer
 202 quit
 203 EOF
 204
 205   chronic nsupdate $ip_arg -k /p/c/machine_specific/vps/filesystem/etc/bind/Kb8.nz.*.private <$tmpf || nsupdate_fails=$((nsupdate_fails + 1))
 206   sed -i 's/^server .*/server bk.b8.nz/' $tmpf
 207   chronic nsupdate $ip_arg -k /p/c/machine_specific/vps/filesystem/etc/bind/Kb8.nz.*.private <$tmpf  || nsupdate_fails=$((nsupdate_fails + 1))
 208   if (( nsupdate_fails > nsupdate_fail_limit )); then
 209     echo error: nsupdate is persistently failing >&2
 210     exit 1
 211   fi
 212   rm -f $tmpf
 213 }
 214
 215 loop-main() {
 216   while true; do
 217     main
 218     sleep 30
 219   done
 220 }
 221
 222 nsupdate_fails=0
 223 if [[ $INVOCATION_ID ]]; then
 224   nsupdate_fail_limit=10
 225   loop-main
 226 else
 227   nsupdate_fail_limit=0
 228   main
 229 fi
 230
 231 exit 0
 232
 233
 234 #   # # persistent initial setup for this:
 235 #   # # create files in /a/c/machine_specific/vps/filesystem/etc/bind
 236 #   # # note, conflink also does some group ownership stuff.
 237 #   mkc /p/c/machine_specific/vps/filesystem/etc/bind
 238 #   sudo dnssec-keygen -a HMAC-SHA512 -b 512 -n HOST b8.nz
 239 #   user=$(id -un)
 240 #   sudo chown $user:$user *
 241
 242
 243 #   f=key.b8.nz
 244 #   cat >$tmpf <<EOF
 245 # key b8.nz. {
 246 # algorithm HMAC-SHA512;
 247 # secret "$(awk '$1 == "Key:" {print $2}' Kb8.nz.*.private)";
 248 # };
 249 # EOF
 250
 251 #   chmod 640 [kK]*
 252
 253 #   # push here?
 254 #   #myunison -ob li
 255 #   #ssh li conflink
 256 #   ssh li.b8.nz systemctl reload named
 257
 258
 259 #   # b8.nz has address 65.96.178.16
 260 #   # b8.nz has IPv6 address 2601:197:600:6efb:82fa:5bff:fe1c:6ecf