URL Monitoring for OpenVPN clients

[Davidsec]

Hi everybody, I configured OpenVPN on a server an I want to monitor URL visited by clients when connected to internet through VPN.Is there any way?

[openvpn_inc]

Hi David,

I assume you must be talking about a full tunnel VPN, --redirect-gateway in openvpn terms. If you're forcing clients' DNS queries through your own nameserver, see that nameserver software's documentation on how to configure it to log all queries. Then find or write some addon software to parse those logs and give you a report.

If your clients are using dnscrypt software for DNS over HTTPS (DoH) and/or DNS over TLS (DoT), while their queries will be forced through the VPN you will not be able to see them.

Likewise, most web traffic these days is encrypted, so the most you will get is the hostname from DNS queries. You won't be able to know the path and arguments after "https://hostname.example/". If you wanted to try to get some of that part, you could run web proxy software.

All in all, this is not a trivial task.

regards, rob0