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 _ ifdev _ < <(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 $gateway in
  23     10.2.0.1)
  24       dynhost=i.b8.nz
  25       ;;
  26     *)
  27       return 0
  28       ;;
  29   esac
  30
  31   athome=false
  32   if [[ -s /dev/shm/dynamic-ip-update-state ]]; then
  33     oldbytes=$(cat /dev/shm/dynamic-ip-update-state)
  34     newbytes=$(awk '$1 == "'$ifdev':" {print $2 + $10}' /proc/net/dev)
  35     if [[ $oldbytes == [1-9]* ]] && (( newbytes >= oldbytes )); then
  36       athome=true
  37       printf "%s\n" "$newbytes" >/dev/shm/dynamic-ip-update-state
  38     fi
  39   fi
  40   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
  41     athome=true
  42     awk '$1 == "'$ifdev':" {print $2 + $10}' /proc/net/dev > /dev/shm/dynamic-ip-update-state
  43   fi
  44
  45
  46   if $athome; then
  47     if ! cur4="$(dig +short $dynhost @iankelling.org | tail -1)"; then
  48       if [[ ! $INVOCATION_ID ]]; then
  49         echo "$0: dig failed. internet looks down. giving up"
  50       fi
  51       return 0
  52     fi
  53     if ip4=$(curl -s4 https://iankelling.org/cgi/pubip); then
  54       if [[ $cur4 && $ip4 && $cur4 != $ip4 ]]; then
  55         up4=true # update ipv4
  56       fi
  57     fi
  58   fi
  59
  60   # may not be set yet so allow fail
  61   cur6="$(host -4 -t aaaa $fqdn iankelling.org | sed -rn 's/.*has IPv6 address (.*)/\1/p;T;q')" ||:
  62
  63   up6=false
  64
  65   out6=$(curl -s6 https://iankelling.org/cgi/pubip) ||: # failure allowed if we have no ipv6
  66
  67   if [[ $out6 ]]; then
  68     dev=$(ip -o a show to $out6 | awk '{print $2}')
  69     # we use slaac with privacy extension, so get our less private more permanent address
  70     mac=$(cat /sys/class/net/$dev/address)
  71
  72     IFS=: read -a f <<<$mac; set -- ${f[@]}
  73     ip6=${out6%:*:*:*:*}:$(printf %x $((0x$1 + 2)))$2:$3'ff:fe'$4:$5$6
  74     # in case we aren't using slaac
  75     if ! ip a | grep "^ *inet6 $ip6/" &>/dev/null; then
  76       ip6=$out6
  77     fi
  78   fi
  79
  80   if [[ $cur6 != $ip6 ]]; then
  81     up6=true
  82   fi
  83
  84   if ! $up4 && ! $up6; then
  85     return 0
  86   fi
  87
  88   # note, a simpler way to do this would be to ssh and use
  89   # "${SSH_CLIENT%% *}
  90   # to update bind if needed.
  91
  92   f=$(mktemp)
  93   cat >>$f <<EOF
  94 server iankelling.org
  95 zone b8.nz
  96 EOF
  97
  98   if $up4; then
  99     cat >>$f <<EOF
 100 update delete $dynhost. A
 101 update add $dynhost. 300 A $ip4
 102 EOF
 103   fi
 104
 105   if $up6; then
 106     if [[ $ip6 ]]; then
 107       cat >>$f <<EOF
 108 update delete $fqdn. AAAA
 109 update add $fqdn. 60 AAAA $ip6
 110 EOF
 111     else
 112       cat >>$f <<EOF
 113 update delete $fqdn. AAAA
 114 EOF
 115     fi
 116   fi
 117
 118   cat >>$f <<EOF
 119 show
 120 send
 121 answer
 122 quit
 123 EOF
 124
 125   nsupdate -k /p/c/machine_specific/vps/filesystem/etc/bind/Kb8.nz.*.private <$f
 126   sed -i 's/^server .*/server bk.b8.nz/' $f
 127   nsupdate -k /p/c/machine_specific/vps/filesystem/etc/bind/Kb8.nz.*.private <$f
 128
 129
 130 }
 131
 132 loop-main() {
 133   while true; do
 134     main
 135     sleep 30
 136   done
 137 }
 138
 139
 140 if [[ $INVOCATION_ID ]]; then
 141   loop-main
 142 else
 143   main
 144 fi
 145
 146 exit 0
 147
 148
 149 #   # # persistent initial setup for this:
 150 #   # # create files in /a/c/machine_specific/vps/filesystem/etc/bind
 151 #   # # note, conflink also does some group ownership stuff.
 152 #   mkc /p/c/machine_specific/vps/filesystem/etc/bind
 153 #   sudo dnssec-keygen -a HMAC-SHA512 -b 512 -n HOST b8.nz
 154 #   user=$(id -un)
 155 #   sudo chown $user:$user *
 156
 157
 158 #   f=key.b8.nz
 159 #   cat >$f <<EOF
 160 # key b8.nz. {
 161 # algorithm HMAC-SHA512;
 162 # secret "$(awk '$1 == "Key:" {print $2}' Kb8.nz.*.private)";
 163 # };
 164 # EOF
 165
 166 #   chmod 640 [kK]*
 167
 168 #   # push here?
 169 #   #myunison -ob li
 170 #   #ssh li conflink
 171 #   ssh li.b8.nz systemctl reload bind9
 172
 173
 174 #   # b8.nz has address 65.96.178.16
 175 #   # b8.nz has IPv6 address 2601:197:600:6efb:82fa:5bff:fe1c:6ecf