Package: setmycfdns
setmycfdns - DNS updates for CloudflareThe scenerio exists where a servers public (external) IP address can change over time.  This is especially true with cloud computing.As instances are stopped or hibernated and then restarted - their public IPs change, leaving public DNS records out of date.This program can be used to update CloudFlare zone records when a server reboots or returns from hibernation. This gives CloudFlare users the same benifit as a cloud-native DNS solutions.Limitationssetmycfdnswill updateexistingDNS records - the records mustalready existin your CloudFlare zone.setmycfdnsdoesn't create or remove records.This is by design to prevent things from going wrong.setmycfdnsupdatesAandAAAADNS records; other records are not supported.setmycfdns Command Usage and OptionsAfter configuringsetmycfdnsis simple to use and in most instances does not require any special switchs.%setmycfdnsThis willautomaticallyfind your public IP address and update the dns zone record based on thefully qualifed domain name(fqdn) of your computer.In a more complex configuration you can use a different name or multiple ip address.%setmycfdns--fqdnfirst.example.com%setmycfdns--fqdnsecond.example.com-ip100.100.22.23A list of all availabe options:% setmycfdns --help
usage: setmycfdns [-h] [-v] [-ip IP] [-fqdn FQDN] [-q] [-z ZONE] [-6]

Update CloudFlare IP record

optional arguments:
  -h, --help            show this help message and exit
  -v, --version         show program's version number and exit
  -ip IP, --ip IP       set specific IP address to use
  -fqdn FQDN, --fqdn FQDN
                        Fully Qualified Domain Name (rkmbp.sunyocc.edu)
  -q, --query           Query only - no updates are made
  -z ZONE, --zone ZONE  Cloudflare Zone to update (optional)
  -6                    Update AAAA record (default is A record)

setmycfdns gunville 2022 v1

#### Automatic IP detection:

By default `setmyip` automatically detects the public IP address by sending an HTTP request to [icanhazip.com](http://icanhazip.com). This site returns the IP address of the sender.

You can optionally use a different site to autodetect the public ip by setting the environment variable `IPAPIURL` to that URL:
```bash
% IPAPIURL='http://api.ipify.org'
% setmycfdnsWhen ipv6 is selected with the-6switch automatic detection uses the ipv6 stack.icanhazip.comworks with both ipv4 and ipv6.If your host has multiple ip addresses or uses a proxy for web requests you will need to provide the ip address to use with the--ip IPcommand line switch.%setmycfdns-ip100.123.4.56
%setmycfdns-6-ip2600:1f16:a44:1701:1be3:f8b7:aa51:410bAutomatic Hostname Determination:The fqdn of the host is acquired with the Pythonsocket.gethostname()function. (Several solutions were tried, none worked perfect, but this one seems to work best.)There are some limitations to hostname determination:Some systems are not configured to provide the fqdn (web01.example.com) and provide only the short hostname (web01). There is no elegant and simple solution that works on all platforms and configurations.In some environments the hostname on the private side (e.g. web01.local) is not the same one used on the public side (web01.example.com).Likewise, cloud VPCs by default provide hostnames in a similar fashion (e.g.ip-172-31-84-22.ec2.internal)In these cases you will be required to provide the full fqdn with the--fqdn FQDNswitch.%setmycfdns--fqdnweb01.example.comCloudFlare Zone selection:The cloudflare zone is selected from the FQDN, but can also explicity provided with the--zone ZONEswitch.If the--zoneswitch is used the the zone does not match the hostname determined above, the fqdn is constructed by appending the zone.%hostname
server1
%setmycfdns--fqdnserver1.example.com# server1.example.com%setmycfdns--fqdnserver1--zoneexample.com# server1.example.com%setmycfdns--zoneeample.com# server1.example.comThe above are identical. Note that thefqdndoes not have to be 'fully qualified' when the--zoneswitch is used.IPv6 SupportBoth ipv4Aand ipv6AAAADNS records are supported bysetmycfdns.  To update ipv6 records the-6switch is used - and required.%setmycfdns-6Installation and Configurationsetmycfdnsis easily installed usingpip%pipinstallsetmycfdnsCloudFlare API KeysCloudFlare credentials (API keys) are required. You will need to generate these in your CloudFlare account.Generally a.cloudflare.cfgfile in the users home directory or the current working directory, but there are several options. The format is dictated by thepython-cloudflareAPI library anddetails can be found here.Remember to always protect these API keys.Configuringsetmycfdnsto Run On Reboots (optional)The followingcrontabentry will runsetmycfdnseach time the server reboots.@reboot /usr/local/bin/setmycfdnsThe actual path depends on where you installsetmycfdnsConfiguringsetmycfdnsTo Run Post Hibernation (optional)This may differ some depending on the operating system. This example here works with RedHat flavors.Create the following file in/lib/systemd/system-sleep/Add these contents of the fileSet the file to be excutable%sudotouch/lib/systemd/system-sleep/20_cfdns
%sudochomd+x/lib/systemd/system-sleep/20_cfdns
%cat>/lib/systemd/system-sleep/20_cfdns<<EOF#!/usr/bin/env bashaction="$1/$2"case"$action"inpre/hibernate);;post/hibernate)/usr/local/bin/setmycfdns;;esac>>The actual path depends on where you installsetmycfdns