RE: Block access to ports

  • From: Lloyd Williams <Williams@xxxxxxxxxxxxxxxxxxxxxxx>
  • To: "'[ExchangeList]'" <exchangelist@xxxxxxxxxxxxx>
  • Date: Wed, 27 Aug 2003 10:31:18 -0400

I might not have a good understanding of how to handle ports, but is it a
fundamental problem that port 135 is one of the most vulnerable ports, but
it is also the port that exchange uses to communicate with Outlook. So if
you close down access to this port you are limiting your self to use
exchange just for POP IMAP and Web Access

Lloyd Williams

 

-----Original Message-----
From: Mike Liddekee [mailto:mliddekee@xxxxxxxxx] 
Sent: Wednesday, August 27, 2003 9:52 AM
To: [ExchangeList]
Subject: [exchangelist] RE: Block access to ports

 

http://www.MSExchange.org/

It all depends on your setup.  If you're trying to block at the firewall
level, you need to determine what type firewall you're using and its setup.
Most firewalls (unless misconfigured) should be set up to not allow any
traffic in unless specifically allowed.  If you're running a router w/ NAT
and no "real" firewall, then that's where most people get burned.  If anyone
tells you NAT is a firewall, run the other direction as fast as you can.
The other way people I know have gotten burned on the latest bug its that
their outer perimeter is great but someone w/ a laptop goes home, dials up,
gets infected, goes back to work and plugs in.  These types of back doors
will kill you every time.  You can block these ports for this one but the
next virus that comes out will require different ports, the next one will
then require different ones, and so on.  It'll be a never ending game of cat
and house.  The thing to do is to make sure things are locked down on your
network to prevent these types of events and that all the proper systems are
in place.  You still can't guarantee yourself 100% (nothing in IT is 100%)
but if you don't have the systems in place you'll be fighting for days every
time a new event comes out.  When I arrived at my current job we had none of
these in place.  After months of fighting, we now how these things in place
and have had no viruses or Trojans of any type (knock on wood). 

 

 

Regards,

Mike Liddekee

Network Engineer

 

Humco Holding Group, Inc.

7400 Alumax Dr. 

Texarkana, TX  75501

Ph:  (903) 831-7808 ext 697

 

-----Original Message-----
From: satish garimalla [mailto:satishgarimalla@xxxxxxxxxxx] 
Sent: Wednesday, August 27, 2003 8:33 AM
To: [ExchangeList]
Subject: [exchangelist] Block access to ports

 

http://www.MSExchange.org/

Hi All,

          I know this is a bit off the topic.But, we are having problems
with the recent virus attacks.We are in the process of eliminating this.

As recommended by symantic web site, Iam supposed to block access to TCP
port 4444 at the firewall level and also block  tcp port 135 "DCOM RPC" and
UDP port 69 , "TFTP"

Can any body explain me how to do this as I am not so familiar with this.All
I want to know is that how to block these ports(from command prompt ?? or
from windows itself  ??) Either may be the case, could you please explain me
the steps in doing so ...

Thanking you very much ,

Satish Garimalla




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Narain Karthikeyan. He's fast, really fast. Want to meet him?
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