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

   1 #!/bin/bash
   2 source ~/.bashrc
   3
   4 main() {
   5
   6   fqdn=$(hostname -f)
   7   domaintmp=${fqdn#*.}
   8   hostnametmp=${fqdn%%.*}
   9   # i for internet
  10   fqdn=${hostnametmp}i.${domaintmp}
  11
  12   up4=false
  13
  14   if ! read -r _ _  gateway _ < <(ip -4 route get 85.119.83.50 2>/dev/null); then
  15     # if our internet is down, just give up, no need to have an error
  16     if [[ ! $INVOCATION_ID ]]; then
  17       echo $0: failed to get route, giving up
  18     fi
  19     exit 0
  20   fi
  21
  22   case $gateway in
  23     10.2.0.1)
  24       dynhost=i.b8.nz
  25       ;;
  26     *)
  27       return 0
  28       ;;
  29   esac
  30
  31   if 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
  32     # we are on a home network
  33     cur4="$(dig +short $dynhost @iankelling.org | tail -1)"
  34     if ip4=$(curl -s4 https://iankelling.org/cgi/pubip); then
  35       if [[ $cur4 && $ip4 && $cur4 != $ip4 ]]; then
  36         up4=true # update ipv4
  37       fi
  38     fi
  39   fi
  40
  41   # may not be set yet so allow fail
  42   cur6="$(host -4 -t aaaa $fqdn iankelling.org | sed -rn 's/.*has IPv6 address (.*)/\1/p;T;q')" ||:
  43
  44   up6=false
  45
  46   out6=$(curl -s6 https://iankelling.org/cgi/pubip) ||: # failure allowed if we have no ipv6
  47
  48   if [[ $out6 ]]; then
  49     dev=$(ip -o a show to $out6 | awk '{print $2}')
  50     # we use slaac with privacy extension, so get our less private more permanent address
  51     mac=$(cat /sys/class/net/$dev/address)
  52
  53     IFS=: read -a f <<<$mac; set -- ${f[@]}
  54     ip6=${out6%:*:*:*:*}:$(printf %x $((0x$1 + 2)))$2:$3'ff:fe'$4:$5$6
  55     # in case we aren't using slaac
  56     if ! ip a | grep "^ *inet6 $ip6/" &>/dev/null; then
  57       ip6=$out6
  58     fi
  59   fi
  60
  61   if [[ $cur6 != $ip6 ]]; then
  62     up6=true
  63   fi
  64
  65   if ! $up4 && ! $up6; then
  66     return 0
  67   fi
  68
  69   # note, a simpler way to do this would be to ssh and use
  70   # "${SSH_CLIENT%% *}
  71   # to update bind if needed.
  72
  73   f=$(mktemp)
  74   cat >>$f <<EOF
  75 server iankelling.org
  76 zone b8.nz
  77 EOF
  78
  79   if $up4; then
  80     cat >>$f <<EOF
  81 update delete $dynhost. A
  82 update add $dynhost. 300 A $ip4
  83 EOF
  84   fi
  85
  86   if $up6; then
  87     if [[ $ip6 ]]; then
  88       cat >>$f <<EOF
  89 update delete $fqdn. AAAA
  90 update add $fqdn. 60 AAAA $ip6
  91 EOF
  92     else
  93       cat >>$f <<EOF
  94 update delete $fqdn. AAAA
  95 EOF
  96     fi
  97   fi
  98
  99   cat >>$f <<EOF
 100 show
 101 send
 102 answer
 103 quit
 104 EOF
 105
 106   nsupdate -k /p/c/machine_specific/vps/filesystem/etc/bind/Kb8.nz.*.private <$f
 107   sed -i 's/^server .*/server bk.b8.nz/' $f
 108   nsupdate -k /p/c/machine_specific/vps/filesystem/etc/bind/Kb8.nz.*.private <$f
 109
 110
 111 }
 112
 113 if [[ $INVOCATION_ID ]]; then
 114   # this is to prevent systemd from filling up the journal
 115   for (( runcount=0; runcount < 100; runcount++ )); do
 116     main
 117     sleep 30
 118   done
 119 else
 120   main
 121 fi
 122
 123
 124
 125
 126
 127 exit 0
 128
 129
 130 #   # # persistent initial setup for this:
 131 #   # # create files in /a/c/machine_specific/vps/filesystem/etc/bind
 132 #   # # note, conflink also does some group ownership stuff.
 133 #   mkc /p/c/machine_specific/vps/filesystem/etc/bind
 134 #   sudo dnssec-keygen -a HMAC-SHA512 -b 512 -n HOST b8.nz
 135 #   user=$(id -un)
 136 #   sudo chown $user:$user *
 137
 138
 139 #   f=key.b8.nz
 140 #   cat >$f <<EOF
 141 # key b8.nz. {
 142 # algorithm HMAC-SHA512;
 143 # secret "$(awk '$1 == "Key:" {print $2}' Kb8.nz.*.private)";
 144 # };
 145 # EOF
 146
 147 #   chmod 640 [kK]*
 148
 149 #   # push here?
 150 #   #myunison -ob li
 151 #   #ssh li conflink
 152 #   ssh li.b8.nz systemctl reload bind9
 153
 154
 155 #   # b8.nz has address 65.96.178.16
 156 #   # b8.nz has IPv6 address 2601:197:600:6efb:82fa:5bff:fe1c:6ecf