On 21/05/14 17:20, Philip Homburg wrote:
On 2014/05/21 17:13 , john wrote:
On 21/05/14 16:58, Philip Homburg wrote:
I'm curious what this firewall is trying to do. If it allows unrestricted outbound connectivity over ssh, but not ssh on port 443. What is that rule trying to protect? Its trying to prevent exactly this. A lot of exploits/malware dial home using the same assumption you do. i.e. 443 will be open. however most of the don't use ssl. With this in mind many IDS will drop anything talking on 443 that isn't ssl/tls. They also do the same protocol analysis on other ports so trying port 80 in this case is also likely to be drooped, as the traffic is not http.
But in those setups, port 22 is usually closed. And if you really want to prevent malware from dialing home, you would have to close all other ports as well.
Typically, I find port 22 closed and then port 443 wide open. So the availability of port 22 is what surprises me. I agree i suspect if one has gone to this much trouble then high ports will also be closed and port 22 will be restricted to know hosts/subnets