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RE: TCP vs UDP
From: "Clint Harris" <clinton.harris () peace com>
Date: Tue, 12 Nov 2002 11:16:12 +1300

When should you block a TCP and UDP port ??? Depends what application
you are using. e.g. As per all that other email banter DNS uses tcp &
udp but standard HTTP uses tcp/80, SMTP tcp/25, IPSec udp/500 ip50/51
and sometimes a TCP or UDP wrapper port, HTTPS tcp/443 etc etc
You'll have to figure out what application you want to allow access or
deny access to and open/block the relevant ports/protocols.

TCP = connection orientated i.e. the transmitting machines shake hands
and make sure that all data is transmitted
UDP = connectionless i.e. the sending party just sends data and "hopes"
that everything gets there.

If you don't need it, block it.


-----Original Message-----
From: Roberto Ramsis [mailto:robertoramsis () hotmail com] 
Sent: Friday, November 08, 2002 11:23 PM
To: security-basics () securityfocus com
Subject: TCP vs UDP


hello
thanks to everyone who replied to my last msg
what's the difference between a port TCP and UDP?
i am talking from a firewall concept,i want to know ,if i need to block
a 
port,when should i block TCP and when UDP and when both?
Thanks in advance

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