# Reverse DNS

## How to add a PTR record

There is a small script that
updates the reverse record for a given ip address.

It can be called on the VPN VM as 

```bash
  /home/jim/scripts/dns/./dyn-reverse-dns.sh <ipv4 ou ipv6> <nom de domaine à y assigner> <serveur DNS à updater>
```

For the moment, the DNS server is 172.16.42.2 (I just set up this
argument for more modularity in the future).

Example: 

```bash
/home/jim/scripts/dns/./dyn-reverse-dns.sh 80.67.181.163 brique.e-jim.be 172.16.42.2
```

It can have those different return codes:

- 0 - All went fine, thank you.
- 1 - First argument is not a valid IP (either v4 or v6)
- 2 - Second argument is not a valid domain name
- 3 - The third argument is not a valid DNS server name or IP
- 4 - The chosen domain name doesn't resolve into the given IP.  [1]
- 5 - nsupdate (the tool used behind) returned an error.
- 33 - There are less or more than 3 arguments

Most of the time, more info can be found in the stdout.

I hope this can help someone implement reverse DNS into ISPng (including
the needed verification that the user has administrative rights on the IP).