Set scripts to new run_directory norm

.gitignore

@@ -1,2 +1,3 @@
 variables.conf
 *.key
+.disabled

README.md

@@ -2,6 +2,9 @@
 
 Source: http://www.btteknik.net/?p=143
 
+### Requirements
+* DiG
+
 ### DNSSEC key
 * need to create a dnssec key, so that we can authenticate clients' updates
 ```
@@ -17,9 +20,19 @@ You may run `install.sh` (not as root, it includes `sudo`s) to:
 * enable timer for next reboot
 * NOTE: if you move the script, you need to install again
 
+### TODO
+* review this README
+
 ### Issues
 
 #### Cannot restrict PTR update
 * We meet an issue when trying to use `tcp-self` in BIND9 zone config
 * https://superuser.com/questions/977132/when-using-nsupdate-to-update-both-a-and-ptr-records-why-do-i-get-update-faile
 * http://www.zytrax.com/books/dns/ch7/xfer.html#update-policy
+
+### Discussions
+#### Dynamic DNS update with ISC DHCP server
+* Use case: DHCP server without fixed addresses
+* `ddns_update` (or something like that) in ISC DHCP Server is something to look into
+* https://flylib.com/books/en/2.684.1/configuring_a_dhcp_server_to_update_a_bind_name_server.html
+  * is it required? see 8.10.3

install.sh

@@ -1,10 +1,17 @@
-#!/bin/bash
+#!/usr/bin/env bash
+
+run_directory=$(dirname $(readlink -f "$0"))
+
+if [ -f $run_directory/.disabled ]; then
+  echo "Installation is disabled. Exiting..."
+  exit 0
+fi
 
 echo "Copying Systemd units to system directory..."
-sudo cp systemd-templates/dns-update.service /etc/systemd/system/
-sudo cp systemd-templates/dns-update.timer /etc/systemd/system/
+sudo cp $run_directory/systemd-templates/dns-update.service /etc/systemd/system/
+sudo cp $run_directory/systemd-templates/dns-update.timer /etc/systemd/system/
 sudo sed -i -e "s/PH_USER/$(whoami)/g" /etc/systemd/system/dns-update.service
-sudo sed -i -e "s/PH_DIRECTORY/$(pwd)/g" /etc/systemd/system/dns-update.service
+sudo sed -i -e "s:PH_DIRECTORY:$run_directory:g" /etc/systemd/system/dns-update.service
 
 echo "Reloading Systemd..."
 sudo systemctl daemon-reload

main.sh

@@ -1,8 +1,9 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
-source variables.conf
+run_directory=$(dirname $(readlink -f "$0"))
+source "$run_directory/variables.conf"
 
-KEY="$(pwd)/dns.key"
+KEY="$run_directory/dns.key"
 TTL=604800
 
 FQDN=$(hostname)
@@ -17,6 +18,12 @@ if [[ ! "$MYIP" =~ ^([1-9]?[0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.([1-9]?[0-9]|1[
 fi
 
 # fetch current record with dig, and choose what to do
+# TODO we should probably improve this choice: current implementation prevents hosts that do not have a record yet to register themselves; We'd need to differentiate cases:
+# * correct ip, not the same -> OK, need to update
+# * correct ip, the same -> OK, nothing to do
+# * no result, name server was reachable -> OK, need to register
+# * no result, name server was not reachable -> NOK, abort
+# * result which is not a correct ip -> NOK, abort
 current_ip_record=$(dig $FQDN +short)
 if [[ "$current_ip_record" =~ ^([1-9]?[0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.([1-9]?[0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.([1-9]?[0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.([1-9]?[0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])$ ]]; then
   if [[ ! "$MYIP" = "$current_ip_record" ]]; then

systemd-templates/dns-update.service

@@ -2,5 +2,6 @@
 Description=Update (if needed) name server with our IP
 
 [Service]
+Type=oneshot
 User=PH_USER
 ExecStart=PH_DIRECTORY/main.sh

systemd-templates/dns-update.timer

@@ -2,7 +2,7 @@
 Description=Run DNS update every 30 minutes
 
 [Timer]
-OnBootSec=1min
+OnBootSec=5min
 OnUnitActiveSec=30min
 
 [Install]

variables.conf.template

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 # Copy this file as variables.conf, with the correct values