Can I open an additional port when a client connects via OpenVPN?

[benbeka]

I know this seems like an odd thing to do, but I have remote workers without static IP addresses and they have a PC with an openvpn client and a separate (hardware) IP phone. My phone system seems to be compromised from a security point of view, so I keep it behind the firewall.

Without putting extra hardware at their end, I'd like to open the IP Phone port through the firewall to their current IP address when they connect through the VPN. When they disconnect, I'd like to close the port again (but it's probably safe enough to do this via a cron job). To complicate matters, there may be several clients connected simultaneously.

Is a floating rule the way to go, or have I missed something obvious. Help and advice would be appreciated.

Thanks

[jimp]

There isn't any mechanism to do that.

What type of phone handset? Some SNOM and Yealink handsets support OpenVPN natively in their firmware

[benbeka]

Thanks for the reply.

Unfortunately it's an older Samsung 7200 system, with woeful security and relatively simple handsets. It looks like an upgrade is the only way to solve this.