From ed7182b665a8792f5b51c2792952599c702dc6fb Mon Sep 17 00:00:00 2001 From: Asif Bacchus Date: Sun, 16 Sep 2018 03:58:05 -0600 Subject: [PATCH] Updated readme with overview of the script and systemd files. --- README.md | 153 +++++++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 152 insertions(+), 1 deletion(-) diff --git a/README.md b/README.md index 73e85f6..6841127 100644 --- a/README.md +++ b/README.md @@ -1,3 +1,154 @@ # CloudflareDDNS -Update DNS records at CloudFlare for dynamic IP address changes via curl and CloudFlare API. \ No newline at end of file +Update your CloudFlare DNS records with your current (dynamic) IP address via +systemd timers and a bash script. + +**NOTE: You can rename *cfddns.sh* anything you want, the script will +auto-update itself. However, you MUST update the systemd service file, +*cfddns.service*, *ExecStart* line manually as explained below** + +## cfddns.sh +#### Installation: +I recommend putting this in your */usr/local/bin* directory or somewhere else in +your path so it's easy to run. +1. Copy the script file to your desired path (/usr/local/bin recommended) and + rename as desired. + ```Bash + sudo cp cfddns.sh /usr/local/bin/ + ``` +2. Make it executable: + ```Bash + sudo chmod +x /usr/local/bin/cfddns.sh + ``` +#### Usage: +If you run the script with no parameters, it will display the help screen. The +script accepts several parameters with 2 being required. The parameters are +summarized here (taken from the help screen). You can access the help screen +and example usage screens by running: *cfddns.sh -h* for help and *cfddns.sh -x* +for examples. + +**-f: account details file with path** +This parameter is *required*. This is the full path to a plain-text file +containing your CloudFlare account details. This file must contain 3 lines in +the following order: +* authorized email address + This is an email address that is permitted to login to your CloudFlare account. +* global api-key + You can get your Global API-key by going to your CloudFlare dashboard, + clicking on your profile picture in the upper-right and opening your profile. + Scroll to the very bottom to the API Keys section. Click on the View button + next to Global API Key. +* zone identifier + You should be able to find this on the Overview page of your CloudFlare dashboard. + +Your completed file should look like: +> johndoe@example.com +> e7882db52804aca6fab22780e055b97056466 +> 492af8aa69f8c44baf043342c74319fd + +You should secure this file by changing the owner of the file to root +```Bash +chown root:root path/to/filename +``` +and then restricting access to only the root user +```Bash +chmod 600 path/to/filename +``` +**-r: target DNS entry to update** +At least one entry here is *required* This is the A or AAAA record you want to +update the IP address for in your DNS zone file. If you have multiple A or AAAA +records you want to update, simply specifiy multiple -r parameters. +*Note: You can only specify *either* A records *or* AAAA records. You have to +update IP4 and IP6 records by running this script multiple times (once for A +records, once for AAAA records even if the hostname is the same).* + +**-4 or -6: type of record to update** +The default option is -4 and it does not need to be specified. This will update +*A records* specified by the -r parameter(s). If you specify -6, then *AAAA +records* will updated as specified by the -r parameter(s). + +**-i: use the specified IP address** +The script will auto-detect the IP address of the machine it's being run on by +accessing an external service and asking for that service to echo the machine's +IP address. If running with -4, then the IP4 will be requested for echo. If +running with -6, then the IP6 addresses will be requested for echo. +This parameter let's you bypass auto-detection and specify a particular address +to be used instead. +*NOTE: The address you supply is NOT checked for correctness. So ensure you're +supplying a valid address of the correct type based on your choice of -4 or -6 +parameter!* + +**-l (lower-case L): specify where the log file should be written** +The script will default to writing it's log file in the same directory as the +script is located. It will use it's own name and append a *.log* extension. +So, the default name for the log file is *cfddns.log*. If you rename the script +*something.sh* then the generated log file name will be *something.log*. +This can be messy if you store the script in /usr/bin/local/ as recommended. +Therefore, it's recommended you choose a different location for +the logfile (*/var/log/cfddns.log* is recommended). + +**-h: display help** +Displays the help screen, which is an abbreviated version of this section you +are currently reading. + +**-x: display examples** +This is the best way to learn how this script works. Several examples are +provided + +## cfddns.service +This is the systemd file that **must** be copied to your */etc/systemd/system* +directory. If you change the name of the cfddns.sh file, you must update the +filename in the *ExecStart* line as shown below: +````Ini +... +[Service] +Type=oneshot +ExecStart=/full/path/to/your/renamed.file +... +```` + +## cfddns.timer +This is the timer file that tells your system how often to call the +cfddns.service file which runs the cfddns.sh script. By default, the timer is +set for 5 minutes after the system boots up (to allow for other processes to +initialize even on slower systems like a RasPi) and then run every 15 minutes +thereafter as long as the system is powered on. Remember when settings your +timer that CloudFlare limits API calls to 1200 every 5 minutes +You can change the timer by modifying the relevant section of the cfddns.timer +file: +````Ini +[Timer] +OnBootSec=5min +OnUnitActiveSec=15min +```` +OnBootSec is how long to wait after the system boots up before executing calling +thd cfddns.service. OnUnitActiveSec will then wait the specified time from that +first (after boot) call before calling cfddns.service again. Therefore, +eveything is relative to your system boot up. I recommend setting +OnUnitActiveSec to a low value (like 2 minutes) for testing then setting it to a +more reasonable time (like 15 minutes) after everything is working. + +## The log file +The script logs every major action it takes and provides details on any errors +it encounters in the log file (see the above section for details on log file +location and name). If errors are encountered, they are colour coded red and +an explanation of the error code is provided. +While the log file is as terse as I felt reasonable, you may still want to +configure any logwatch programs to further filter things for you so you don't +have to review this log as part of your daily routine. To make that easier, the +following conventions are observed in the log file: +* Errors always appear as "-- [ERROR] text and error code here --" +* Errors are followed by an explanation of the specific error code on a new line +* A clean exit appears as "-- [SUCCESS] some text here --" +* The script always starts a new set of log entries with "-- Start CloudFlare + DDNS script execution -- +* All log file entries start with a time-stamp in [square brackets] + +## Final thoughts +I'm by no means an expert in BASH scripting and I only program/script as a hobby +when I find stuff that irritates me and no other good solutions seem easily +available. So, by all means, please comment, provide feedback and suggestions +to make this script better! Thanks, I hope this helps someone else out! + +Please check out my blog at [https://mytechiethoughts.com](https://mytechiethoughts.com) where I tackle +problems like this all the time and find free/cheap solutions to tech problems. \ No newline at end of file