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From: gentuxx <gentuxx@gmail.com>
To: gentoo-user@lists.gentoo.org
Subject: Re: [gentoo-user]  Re: OT: A netbios-ssn blocking rule?
Date: Wed, 23 Aug 2006 14:46:25 -0700	[thread overview]
Message-ID: <44ECCCB1.3000806@gmail.com> (raw)
In-Reply-To: <44ECC994.8020705@ilievnet.com>

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Daniel Iliev wrote:
> James wrote:
>>> Daniel Iliev <danny <at> ilievnet.com> writes:
>>>     
>>
>> My iptables based firewall seem to be working, However, I keep getting triplets
>> of this activity:
>>
>> curious.ip www.me.com tcp     2286 > netbios-ssn Seq=0 Len=0 MSS=1460
>> www.me.com curious.ip tcp     netbios-ssn > 2286 [RST, ACK] Seq=0 Ack=1 
>>  Win=0 Len=0
>>
>> similar problem (2469 > microsoft-ds)
>>  Other problems are (info section is only difference) epmap > 3081
>>
>>
>>
>>   
>>> "iptables -A INPUT -p tcp --dport microsoft-ds -j DROP" ( < the packets
>>> have destination the FW itself)
>>> "iptables -A FORWARD -d *target-PC* -p tcp --dport microsoft-ds -j DROP"
>>> ( < the packets have destination the "target-PC". )
>>>     
>>
>> Your advice is working, beautiful
>>
>> Much Thanks!
>>
>>
>> James
>>
>>
>>
>>   
> I'm not sure if get this message right, but if it is a question how to
> deal with packets like these:
> 
>> curious.ip www.me.com tcp     2286 > netbios-ssn Seq=0 Len=0 MSS=1460
>> www.me.com curious.ip tcp     netbios-ssn > 2286 [RST, ACK] Seq=0 Ack=1 
> 
> the answer is: Add the same rules, but replace "microsoft-ds" with "netbios-ssn" or the corresponding number from /etc/services. Those rules would look like:
> "iptables -A INPUT -p tcp --dport netbios-ssn -j DROP"
>  it's the same as:
> "iptables -A INPUT -p tcp --dport 139 -j DROP"
> 
> And if the target is not the FW:
> iptables -A FORWARD -d *target-PC* -p tcp --dport netbios-ssn -j DROP
> or
> iptables -A FORWARD -d *target-PC* -p tcp --dport 139 -j DROP
> 
> 
> It seems that you want to stop the ms netbios activity. The ports used
> for this service are 137,138,139 and 445 so the rule-set could be
> something like this:
> 
> iptables -A FORWARD -d *target-PC* -p tcp --dport 445 -j DROP
> iptables -A FORWARD -d *target-PC* -p tcp --dport 137:139 -j DROP
> 
> or 
> 
> iptables -A INPUT -p tcp --dport 445 -j DROP
> iptables -A INPUT -p tcp --dport 137:139 -j DROP
> 
> 

Actually, some of those ports are UDP.  /etc/services says the same for
both TCP and UDP.  So if -p is required for --dport, you would have to
add rules for UDP as well.

iptables -A FORWARD -d *target-PC* -p udp --dport 137:139 -j DROP
iptables -A INPUT -p udp --dport 137:139 -j DROP

- --
gentux
echo "hfouvyyAhnbjm/dpn" | perl -pe 's/(.)/chr(ord($1)-1)/ge'

gentux's gpg fingerprint ==> 5495 0388 67FF 0B89 1239  D840 4CF0 39E2
18D3 4A9E
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Version: GnuPG v1.4.5 (GNU/Linux)
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org

iD8DBQFE7MyxTPA54hjTSp4RAhjGAKCUmxCgS62ZjCKhGsUW28M25UfnVgCfeHer
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gentoo-user@gentoo.org mailing list



  reply	other threads:[~2006-08-23 21:52 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-08-18 19:24 [gentoo-user] blocking netbios-ssn rule? James
2006-08-18 19:59 ` [gentoo-user] OT: A netbios-ssn blocking rule? James
2006-08-18 21:43 ` Daniel Iliev
2006-08-21  4:11   ` [gentoo-user] " James
2006-08-23 21:33     ` Daniel Iliev
2006-08-23 21:46       ` gentuxx [this message]
2006-08-24  1:36         ` Daniel Iliev

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