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

   1 #!/bin/bash
   2 source ~/.bashrc
   3
   4
   5
   6 main() {
   7
   8   fqdn=$(hostname -f)
   9   domaintmp=${fqdn#*.}
  10   hostnametmp=${fqdn%%.*}
  11   # i for internet
  12   fqdn=${hostnametmp}i.${domaintmp}
  13
  14   up4=false
  15
  16   if ! read -r _ _  gateway _ ifdev _ < <(ip -4 route get 85.119.83.50 2>/dev/null); then
  17     # if our internet is down, just give up, no need to have an error
  18     if [[ ! $INVOCATION_ID ]]; then
  19       echo $0: failed to get route, giving up
  20     fi
  21     exit 0
  22   fi
  23
  24   case $gateway in
  25     10.2.0.1)
  26       dynhost=i.b8.nz
  27       ;;
  28     *)
  29       return 0
  30       ;;
  31   esac
  32
  33   athome=false
  34   if [[ -s /dev/shm/dynamic-ip-update-state ]]; then
  35     oldbytes=$(cat /dev/shm/dynamic-ip-update-state)
  36     newbytes=$(awk '$1 == "'$ifdev':" {print $2 + $10}' /proc/net/dev)
  37     if [[ $oldbytes == [1-9]* ]] && (( newbytes >= oldbytes )); then
  38       athome=true
  39       printf "%s\n" "$newbytes" >/dev/shm/dynamic-ip-update-state
  40     fi
  41   fi
  42   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
  43     athome=true
  44     awk '$1 == "'$ifdev':" {print $2 + $10}' /proc/net/dev > /dev/shm/dynamic-ip-update-state
  45   fi
  46
  47
  48   if $athome; then
  49     cur4="$(dig +short $dynhost @iankelling.org | tail -1)"
  50     if ip4=$(curl -s4 https://iankelling.org/cgi/pubip); then
  51       if [[ $cur4 && $ip4 && $cur4 != $ip4 ]]; then
  52         up4=true # update ipv4
  53       fi
  54     fi
  55   fi
  56
  57   # may not be set yet so allow fail
  58   cur6="$(host -4 -t aaaa $fqdn iankelling.org | sed -rn 's/.*has IPv6 address (.*)/\1/p;T;q')" ||:
  59
  60   up6=false
  61
  62   out6=$(curl -s6 https://iankelling.org/cgi/pubip) ||: # failure allowed if we have no ipv6
  63
  64   if [[ $out6 ]]; then
  65     dev=$(ip -o a show to $out6 | awk '{print $2}')
  66     # we use slaac with privacy extension, so get our less private more permanent address
  67     mac=$(cat /sys/class/net/$dev/address)
  68
  69     IFS=: read -a f <<<$mac; set -- ${f[@]}
  70     ip6=${out6%:*:*:*:*}:$(printf %x $((0x$1 + 2)))$2:$3'ff:fe'$4:$5$6
  71     # in case we aren't using slaac
  72     if ! ip a | grep "^ *inet6 $ip6/" &>/dev/null; then
  73       ip6=$out6
  74     fi
  75   fi
  76
  77   if [[ $cur6 != $ip6 ]]; then
  78     up6=true
  79   fi
  80
  81   if ! $up4 && ! $up6; then
  82     return 0
  83   fi
  84
  85   # note, a simpler way to do this would be to ssh and use
  86   # "${SSH_CLIENT%% *}
  87   # to update bind if needed.
  88
  89   f=$(mktemp)
  90   cat >>$f <<EOF
  91 server iankelling.org
  92 zone b8.nz
  93 EOF
  94
  95   if $up4; then
  96     cat >>$f <<EOF
  97 update delete $dynhost. A
  98 update add $dynhost. 300 A $ip4
  99 EOF
 100   fi
 101
 102   if $up6; then
 103     if [[ $ip6 ]]; then
 104       cat >>$f <<EOF
 105 update delete $fqdn. AAAA
 106 update add $fqdn. 60 AAAA $ip6
 107 EOF
 108     else
 109       cat >>$f <<EOF
 110 update delete $fqdn. AAAA
 111 EOF
 112     fi
 113   fi
 114
 115   cat >>$f <<EOF
 116 show
 117 send
 118 answer
 119 quit
 120 EOF
 121
 122   nsupdate -k /p/c/machine_specific/vps/filesystem/etc/bind/Kb8.nz.*.private <$f
 123   sed -i 's/^server .*/server bk.b8.nz/' $f
 124   nsupdate -k /p/c/machine_specific/vps/filesystem/etc/bind/Kb8.nz.*.private <$f
 125
 126
 127 }
 128
 129 loop-main() {
 130   while true; do
 131     main
 132     sleep 30
 133   done
 134 }
 135
 136
 137 if [[ $INVOCATION_ID ]]; then
 138   loop-main
 139 else
 140   main
 141 fi
 142
 143 exit 0
 144
 145
 146 #   # # persistent initial setup for this:
 147 #   # # create files in /a/c/machine_specific/vps/filesystem/etc/bind
 148 #   # # note, conflink also does some group ownership stuff.
 149 #   mkc /p/c/machine_specific/vps/filesystem/etc/bind
 150 #   sudo dnssec-keygen -a HMAC-SHA512 -b 512 -n HOST b8.nz
 151 #   user=$(id -un)
 152 #   sudo chown $user:$user *
 153
 154
 155 #   f=key.b8.nz
 156 #   cat >$f <<EOF
 157 # key b8.nz. {
 158 # algorithm HMAC-SHA512;
 159 # secret "$(awk '$1 == "Key:" {print $2}' Kb8.nz.*.private)";
 160 # };
 161 # EOF
 162
 163 #   chmod 640 [kK]*
 164
 165 #   # push here?
 166 #   #myunison -ob li
 167 #   #ssh li conflink
 168 #   ssh li.b8.nz systemctl reload bind9
 169
 170
 171 #   # b8.nz has address 65.96.178.16
 172 #   # b8.nz has IPv6 address 2601:197:600:6efb:82fa:5bff:fe1c:6ecf