Solved

Firewall/Port information

Posted on 2003-12-09
4
1,652 Views
Last Modified: 2013-11-16
Hi,
I believe I have an okay understanding of how port numbers work. I just bought a router and firewall software. I need to know how do I configure the firewall, in other words, how do I know which local ports to block to avoid intruders. Thanks for any help on this.
0
Comment
Question by:bduffy120
4 Comments
 
LVL 79

Accepted Solution

by:
lrmoore earned 250 total points
ID: 9905462
Most software firewalls block all incoming traffic by default, unless you've specifically requested it. If you're behind a router that is doing NAT (Network address translation), then it is providing a first "shield" to make you virtually invisible to start with. Depending on what all you have on your local LAN, and the software firewall that you have, you might have a checkbox "allow local LAN access" or "allow netbios"
0
 
LVL 1

Expert Comment

by:NeilDavis
ID: 9905464
Its easier to block all ports and them open up only the ones you need for mail and internet access.  Your router also may have port filtering which is worth a look.

80 - HTTP - Internet, 110 - pop3 - email etc.  All port numbers are listed here:

http://www.iana.org/assignments/port-numbers

0
 
LVL 41

Expert Comment

by:stevenlewis
ID: 9905935
go to www.grc.com and test your sheilds and scan your ports
chances are they are already blocked, and you may be back here asking how to open some (for games, etc)
0
 
LVL 25

Expert Comment

by:mikeleebrla
ID: 9912665
inless you are running a www or mail server, do not open port 80 or 110... you will still be able to get to the web and get your mail with these ports closed since your firewall sees that these connections were started from the "inside" and not the "outside" so it will allow them to come thru.   If you do open these ports you will have to do port forwarding to direct them to a particular machine on the inside since what is actually going on is PAT (port address translation).
0

Featured Post

What is SQL Server and how does it work?

The purpose of this paper is to provide you background on SQL Server. It’s your self-study guide for learning fundamentals. It includes both the history of SQL and its technical basics. Concepts and definitions will form the solid foundation of your future DBA expertise.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Let’s list some of the technologies that enable smooth teleworking. 
In this article, I am going to show you how to simulate a multi-site Lab environment on a single Hyper-V host. I use this method successfully in my own lab to simulate three fully routed global AD Sites on a Windows 10 Hyper-V host.
After creating this article (http://www.experts-exchange.com/articles/23699/Setup-Mikrotik-routers-with-OSPF.html), I decided to make a video (no audio) to show you how to configure the routers and run some trace routes and pings between the 7 sites…
In this tutorial you'll learn about bandwidth monitoring with flows and packet sniffing with our network monitoring solution PRTG Network Monitor (https://www.paessler.com/prtg). If you're interested in additional methods for monitoring bandwidt…

773 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question