full-disclosure - reduction of brute force log

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Date: Tue Feb 28 16:52:42 2006
From: rsradvan at unixworks.net (Bob Radvanovsky)
Subject: reduction of brute force log

I am going to test these rules out -- this looks REALLy good!  But...I've got just ONE question: why on Earth would you permit ICMP???

And what significances are ports 50, 51, 1599, 1600 and 1601?  443 and 80 are HTTP-S and HTTP (respectively), 123 is NTP -- I realize that, but what are these others ports used for?

-r

*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
:RH-Firewall-1-INPUT - [0:0]
-A INPUT -j RH-Firewall-1-INPUT
-A FORWARD -j RH-Firewall-1-INPUT
-A RH-Firewall-1-INPUT -i lo -j ACCEPT
-A RH-Firewall-1-INPUT -s 10.0.0.0/24 -j ACCEPT
-A RH-Firewall-1-INPUT -p icmp --icmp-type any -j ACCEPT
-A RH-Firewall-1-INPUT -p 50 -j ACCEPT
-A RH-Firewall-1-INPUT -p 51 -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 22 -m recent --rcheck --name SSH -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 80 -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state NEW -m udp -p udp --dport 123 -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 443 -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 1599 -m recent --name SSH --remove -j DROP
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 1600 -m recent --name SSH --set -j DROP
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 1601 -m recent --name SSH --remove -j DROP
-A RH-Firewall-1-INPUT -j REJECT --reject-with icmp-host-prohibited
COMMIT


----- Original Message -----
From: Matthijs van Otterdijk [mailto:thotter@...il.com]
To: full-disclosure@...ts.grok.org.uk
Subject: Re: [Full-disclosure] reduction of brute force login attempts via SSH	through iptables --hashlimit


> I haven't tried this myself, and I don't know if it is already suggested,
> but this should stop all the pesky scriptkiddies from filling up your logs.
> Might prove to be a better solution, who knows:
> http://aplawrence.com/Security/sshloginattack.html
> 
> Matthijs
> 
>