Initial commit

2026-04-25 18:00:56 +02:00
parent 0b1a002ffc
commit bfb02d30de
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+### Prerequisites
+ - Use Cloudflare DNS
+ - [Powershell installed](obsidian://open?vault=Glamdring%202&file=PowerShell%20on%20Debian)
+
+
+### Step 1 - Get a Token
+Get a Cloudflare API token with the necessary permissions. Log in to your CloudFlare account, go to `Manage Account` and to `Account API Tokens`. Click that big, blue `Create Token` button and select the `Edit zone DNS` template.
+
+Select the relevant Zone Resources, I just gave it permissions to edit all my zones:
+![[Pasted image 20250415131506.png]]
+
+Once you've configured it all, continue to summary, click `Create Token` and remember to save it. It will only be shown once, so if you forget to save it you'll have to create a new token.
+
+### Step 2 - The Script
+Create the PowerShell script file on whatever server you want to run this. Using your web server would be a good choice.
+```
+nano /etc/ipfixer.ps1
+```
+Create the file whereever you want, I'm not your mom.
+
+Paste in the script, remember to add the token you created in step 1:
+```
+#Dealing with my Cloudflare domains and my dynamic IP
+$ProgressPreference = "SilentlyContinue"
+$timeStamp = (get-Date).ToUniversalTime().ToString("yyyy-MM-ddTHH:mm:ss")
+$cfToken = "MkayyyYourTokenGoesHere"
+$myIp = curl "api.ipify.org" #Curl is easier for this one
+$cfAPIBaseURI = "https://api.cloudflare.com/client/v4/"
+#Get an auth token
+$cfHeaders = @{
+    "Authorization" = "Bearer $cfToken"
+} 
+
+#Pull the DNS zones
+$zones = ((Invoke-WebRequest -URI "$($cfAPIBaseURI)zones" -Method GET -Headers $cfHeaders -UseBasicParsing).content | ConvertFrom-JSON).Result
+
+#Get the DNS records for the zones, except the TailScale records
+$zones | Foreach-Object{
+    $zoneId = $_.id
+    $dnsRecords = ((Invoke-WebRequest -URI "$($cfAPIBaseURI)zones/$($_.id)/dns_records" -Method GET -Headers $cfHeaders -UseBasicParsing).content | ConvertFrom-JSON).Result | Where-Object{($_.type -eq "A") -and ($_.content -notMatch "^100")} | Select-Object id, name, type, content
+
+    #Update the DNS record to use the correct IP
+    $dnsRecords | where-Object{$_.content -ne $myIp} | Foreach-object{
+        $oldIp = $_.content
+        $recordBody = @{
+            comment = "$TimeStamp | Updated automatically from $oldIp to $myIp"
+            content = "$myIp"
+        } | ConvertTo-JSON
+        $ipFix = Invoke-WebRequest -URI "$($cfAPIBaseURI)zones/$($zoneId)/dns_records/$($_.id)" -Method PATCH -Body $recordBody -Headers $cfHeaders
+        If($ipFix.statuscode -match "20."){
+            Write-output "Successfully changed the A-record $($_.name) from $oldIp to $myIp."
+        }
+        If($ipFix.statuscode -notMatch "20."){
+            Write-error "Failed to change the A-record $($_.name) from $oldIp to $myIp."
+        }
+    }
+}
+```
+A few things to note in the script above:
+ - All TailScale IPs (or other IPs starting with 100) are ignored, as is everything but A-records.
+ - If a record is updated, a comment is added to it on Cloudflare:
+   ![[Pasted image 20250415132520.png]]
+
+### Step 3 - Automation (cron)
+The entire point was to automate everything, so let's set up a cron job (scheduled task)
+```
+crontab -e
+```
+This uses your default text editor. If it's something insane like Vim, you might want to [change it](https://linuxsimply.com/linux-basics/text-editors/default/).
+
+Just like Regex, cron is pretty simple once you've learned it. Every line added to the file consists of 6 space-separated properties:
+1. The minute
+2. The hour
+3. The day of the month
+4. The month of the year
+5. The day of the week
+6. The command to run
+
+This means that to run the command `pwsh /etc/ipfixer.ps1` every hour, on the hour, you need to add this line:
+```
+0 * * * * pwsh /etc/ipfixer.ps1
+```
+Feel free to get creative with the schedule if you like, [good info here](https://vitux.com/how-to-setup-a-cron-job-in-debian/).