Apache vulnerability?

Alex mysqlstudent at gmail.com
Wed Nov 2 01:23:05 UTC 2011


>>> This looks to me like tcp on dport 22 is allowed and there I would think
>>> that the minimal change would be to insert a rule before this which says
>>> "anything from offending_ip via tcp should be rejected".
>>> I'm still trying to get comfortable with iptables and, even though there
>>> is alot of stuff out there, I'm still working to get the necessary
>>> critical mass of understanding so it all falls into place. This thread
>>> looked like a good chance to see if I'm closer to understanding.
>> Yes, that's a good approach too. If you are editing the existing
>> iptables config script from /etc/sysconfig/iptables, then that's
>> exactly what you would do. Something like this should work:
>> # Firewall configuration written by system-config-firewall
>> # Manual customization of this file is not recommended.
>> *filter
>> :INPUT ACCEPT [0:0]
>> -A INPUT -p icmp -j ACCEPT
>> -A INPUT -i lo -j ACCEPT
>> -A INPUT -m state --state NEW -m tcp -p tcp --dport 80 -j DROP -s
>> <offending_ip/range>
>> -A INPUT -m state --state NEW -m tcp -p tcp --dport 25 -j ACCEPT
>> -A INPUT -m state --state NEW -m tcp -p tcp --dport 80 -j ACCEPT
>> -A INPUT -m state --state NEW -m tcp -p tcp --dport 443 -j ACCEPT
>> -A INPUT -m state --state NEW -m tcp -p tcp --dport 22 -j ACCEPT
>> the "<offending_ip/range>" might be something like to block
>> the entire 256 addresses on that network.
>> HTH,
>> Alex
> Alex:
> Thanks ... it does help to get a confirm that my understanding your
> example is at least in the general right direction.
> Just to check to make sure I got the last bit of info right ...
> In your particular example of what appears to be China Telecom, are you
> assuming that they are using the ip and that translates to
> 1.2.3.[0-255]?

Yes, that's correct. Search for CIDR notation.

> I have a LAN which assumes router connecting to outside world is
> and my network is 192.168.2.* (wireless only engaged when
> necessary for both and one Linksys at To me,
> this means that I "only have one IP address on that host" per your
> email. If I am correct, I don't need to worry about a generalized
> rule on each machine to prevent something I don't know about.

Yes, that's correct, but I was really referring to the destination --
if you wanted to block more than one host at a time, such as for an
entire ISP in China, for example. So from my original log entry
example of, you might do:

# iptables -j DROP -I INPUT -s

This would block all access from that host to your network.

> The addition of 25, 80, and 443 ports are your suggestions for what to
> allow as opposed to manditories (everything is working nicely on my
> system with the default and the only other port access I need to do is
> in sendmail.mc).

I wasn't sure if that was from the original rulebase or if it was
something I added :-)

The default is to allow everything, but there is a ICMP reject rule at
the bottom of the rulebase that rejects everything else for which
there is no rule such as those for port 25 and 80.


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