83 lines
3.7 KiB
Markdown
83 lines
3.7 KiB
Markdown
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### Prerequisites
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- Use Cloudflare DNS
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- [Powershell installed](obsidian://open?vault=Glamdring%202&file=PowerShell%20on%20Debian)
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### Step 1 - Get a Token
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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.
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Select the relevant Zone Resources, I just gave it permissions to edit all my zones:
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![[Pasted image 20250415131506.png]]
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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.
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### Step 2 - The Script
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Create the PowerShell script file on whatever server you want to run this. Using your web server would be a good choice.
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```
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nano /etc/ipfixer.ps1
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```
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Create the file whereever you want, I'm not your mom.
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Paste in the script, remember to add the token you created in step 1:
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```
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#Dealing with my Cloudflare domains and my dynamic IP
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$ProgressPreference = "SilentlyContinue"
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$timeStamp = (get-Date).ToUniversalTime().ToString("yyyy-MM-ddTHH:mm:ss")
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$cfToken = "MkayyyYourTokenGoesHere"
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$myIp = curl "api.ipify.org" #Curl is easier for this one
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$cfAPIBaseURI = "https://api.cloudflare.com/client/v4/"
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#Get an auth token
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$cfHeaders = @{
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"Authorization" = "Bearer $cfToken"
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}
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#Pull the DNS zones
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$zones = ((Invoke-WebRequest -URI "$($cfAPIBaseURI)zones" -Method GET -Headers $cfHeaders -UseBasicParsing).content | ConvertFrom-JSON).Result
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#Get the DNS records for the zones, except the TailScale records
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$zones | Foreach-Object{
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$zoneId = $_.id
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$dnsRecords = ((Invoke-WebRequest -URI "$($cfAPIBaseURI)zones/$($_.id)/dns_records" -Method GET -Headers $cfHeaders -UseBasicParsing).content | ConvertFrom-JSON).Result | Where-Object{($_.type -eq "A") -and ($_.content -notMatch "^100")} | Select-Object id, name, type, content
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#Update the DNS record to use the correct IP
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$dnsRecords | where-Object{$_.content -ne $myIp} | Foreach-object{
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$oldIp = $_.content
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$recordBody = @{
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comment = "$TimeStamp | Updated automatically from $oldIp to $myIp"
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content = "$myIp"
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} | ConvertTo-JSON
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$ipFix = Invoke-WebRequest -URI "$($cfAPIBaseURI)zones/$($zoneId)/dns_records/$($_.id)" -Method PATCH -Body $recordBody -Headers $cfHeaders
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If($ipFix.statuscode -match "20."){
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Write-output "Successfully changed the A-record $($_.name) from $oldIp to $myIp."
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}
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If($ipFix.statuscode -notMatch "20."){
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Write-error "Failed to change the A-record $($_.name) from $oldIp to $myIp."
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}
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}
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}
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```
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A few things to note in the script above:
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- All TailScale IPs (or other IPs starting with 100) are ignored, as is everything but A-records.
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- If a record is updated, a comment is added to it on Cloudflare:
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![[Pasted image 20250415132520.png]]
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### Step 3 - Automation (cron)
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The entire point was to automate everything, so let's set up a cron job (scheduled task)
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```
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crontab -e
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```
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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/).
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Just like Regex, cron is pretty simple once you've learned it. Every line added to the file consists of 6 space-separated properties:
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1. The minute
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2. The hour
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3. The day of the month
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4. The month of the year
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5. The day of the week
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6. The command to run
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This means that to run the command `pwsh /etc/ipfixer.ps1` every hour, on the hour, you need to add this line:
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```
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0 * * * * pwsh /etc/ipfixer.ps1
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```
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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/).
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