Why is TCP port 53 open on the Balance 20? What other ports are open by default and under what conditions? UDP port 500 gets open for IPsec, for example.
Possible to share us the firmware version running for your B20 ? We will always recommend to use the latest firmware for any vulnerability scanning.
Beside that, which interface you are scanning for the B20 ? LAN or WAN ?
The firmware is version 6.2.2 and I’m scanning the WAN1 interface. I can’t upgrade to 6.3 (which just came out) yet.
We don’t have port TCP 53 opened by default. I have tested this. Have you configured Port Forwarding for TCP 53?
No sir. However, under Network / LAN I do have DNS Caching enabled, which is not a default setting. This requires DNS Proxy to be enabled. Could this be it?
Enabled DNS Caching will not open port TCP 53. Please open ticket for us to investigate.
Any resolution to this? I have a Balance 305 with multiple ports open to the outside that are not defiled in the inbound rules.