Allow connections to apache from a dynamic IP

Question

When setting up an Apache server, it's obviously possible to allow connections from a specific IP address [/range].

I have a dynamic IP and I'm wondering, if I use a DDNS service, whether it's possible to allow connections if the incoming IP matches the current DDNS IP? I'm aware you could make a task to run every few minutes, ping and update the config file with the current IP address, but that would require a service restart which I'd like to avoid if possible.

Answer 1

The forward-dns directive seems to be what you're after. According to the docs, it

simply queries the DNS for the host name and allows a client if its IP matches. As a consequence, it will only work with host names, not domain names. However, as the reverse DNS is not used, it will work with clients which use a dynamic DNS service.

So you can specify something like

<Location / >
    Require forward-dns your.ddns.server
</Location>

and it will do a DNS query whenever a client connects, and denies the connection if it is not from the specified name. Two things to consider:

1. The forward-dns directive is available from 2.4.19.
2. Caching DNS servers can still cause some surprise.