It's not very safe to disable the firewall.

The HG612 firewall is best left up at all times (preferably with the "standard" ruleset, or better).
Otherwise rogues can log-in remotely via the embedded web server or via the telnetd interface to do all sorts of nasties. They could, e.g., install
tcpdump on your router, and intercept all your traffic, perhaps even steal your entire p0rn stash!
The firewall on the HG612 is a standard Linux stateful packet inspection firewall. It comes in two parts, the
netfilter kernel modules, and the userspace tool
iptables.
While logged in to the Huawei via a telnet shell, it's possible to list all the rules in the current firewall chains using
iptables. As a firewall, the barest safeguard is to drop incoming packets to 22/tcp, 23/tcp and 80/tcp.
| Text |
1
23
45
67
89
1011
1213
1415
| # iptables -L -n
...Chain INPUT_SERVICE_ACL (1 references)
target prot opt source destination ACCEPT all -- 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:23
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:80 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:80
ACCEPT icmp -- 0.0.0.0/0 0.0.0.0/0 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:8081
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:23 DROP tcp -- 0.0.0.0/0 0.0.0.0/0 multiport dports 21,80,22,23,8081 <----
DROP icmp -- 0.0.0.0/0 0.0.0.0/0 ... |
With the firewall
disabled this is how the HG612 appears to an intruder*:
HG612 - Firewall Disabled (several critical network services open to every Tom, Dick and Harriet).
With the firewall
enabled (with "standard" ruleset), this is how the HG612 appears to an intruder*:
HG612 - Firewall Enabled (sshd, telnetd, httpd all closed and stealthed by a DROP rule)
End-user security is probably a (valid) reason that Beatie locked down the GUI for the HG612.
cheers, a
* These are only network scans of common ports. Not shown in the grc.com scan, but nevertheless running by default is Beatie's remote management daemon, btagent which listens on 161/udp and 161/tcp. There are a couple other network services, too.
For the professional paranoiac, the
netstat tool will list every network daemon running on the Huawei.
Edited by deleted (Mon 05-Nov-12 23:35:47)