Re: ISP Filtering (Survey of Sorts)

From: Jens Hektor (hektorat_private-Aachen.DE)
Date: Sat Jun 02 2001 - 09:39:18 PDT

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    macdaddyat_private wrote:
    
    > 1-19 I/O  (there isn't any reason why a user should be using these ports)
    > 
    > 61/62 I (there isn't any reason why someone should be query *any* of our
    > devices via SNMP)
    
    Should read 161/162.
    
    > 111 I/O (talk about hack me please...)
    > 
    > 135-139 I/O (no reason to allow this.  too much info can be gathered with
    > NO log entry on the queried box.  most are misconfigured and allow access
    > to way too much)
    > 
    > 53 where possible (few client nodes should be queried for DNS.  Most of
    > our users are basic dialups.  Some DSL, very little business DSL or leased
    > line.  Those people plus our own DNS servers need to be allowed for.)
    > 
    > netbus/BO ports  (let's halt the problem before it starts)
    
    I think this is good practice.
    
    Additionally I would suggest tftp/bootps.
    
    > I've seriously been thinking about blocking connections TO port 25 on our
    > client (non-business) nodes.  We'd still allow them to use any SMPT server
    
    Establish a virus-scanning relay and most of them will be happy.
    
    Bye, Jens
    
    -- 
    Jens Hektor, RWTH Aachen, Rechenzentrum, Seffenter Weg 23, 52074 Aachen
    Computing Center Technical University Aachen, network operation & security
    mailto:hektorat_private-Aachen.DE, Tel.: +49 241 80 4866
    



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