What ufw allows/denies by default?
- by mgibsonbr
I was accessing a server running Ubuntu 12.04 Server using SSH and managed to lock myself out of it. I'm still wondering how that happened:
The firewall was enabled by default;
sudo ufw status did not show any rules (but I could SSH to the server normally);
I tried explicitly allowing ports 80 and 443 using the commands:
sudo ufw allow 80
sudo ufw allow 443
sudo ufw status now showed something like:
Status: active
To Action From
-- ------ ----
80 ALLOW Anywhere
80 ALLOW Anywhere (v6)
443 ALLOW Anywhere
443 ALLOW Anywhere (v6)
(Recalling from memory and seeing some examples; I can't access the server to see the exact output, so I might be mistaken)
After logging out of SSH, now I can't log in anymore (connection timeout).
What just happened? There were no DENY rules previously (AFAIK), neither I introduced any. How could SSH be previously available and now it's not? Does ufw (or more precisely iptables) allow everything by default, unless you explicitly allow something, then it denies everything by default? Or did I do something wrong, that broke the existing rules somehow?
