Question about outbound Firewall rule


#1

The article below shows how some modems can be reset and/or rebooted by malicious web pages because they don’t have any password protection

www.gironsec.com/blog/2015/01/owning_modems_and_routers_silently/

My Surf SOHO has a single wired WAN connection. The modem is at 192.168.100.1 which is reachable from the LAN. I set an outbound firewall rule to block this IP address and it works fine.

My question is what would happen if I blocked access to anything starting with 192.168 in an outbound firewall rule?
Specifically, would I still be able to access my router which has a 192.168.4.4 IP address?
And would I be able to access my printer which is at 192.168.4.5?
I ask because my next modem may have a different 192.168.x.x IP address.

Obviously, I am afraid to test this for fear of locking myself out. Thanks.


#2

Firewall outbound rule blocks the traffic from LAN to WAN. If you block 192.168.0.0/16, LAN users will not able to access the modem.

Surf Soho (192.168.4.4) and printer (192.168.4.5) are on LAN side, so not affected by outbound firewall rule. This is an expected behavior.


#3

Thank you.