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how dangrous to have open TCP ports ??

Posted on 2004-10-22
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Last Modified: 2013-11-29
hello..
i have on my computer many opened TCP ports  !! ..
how can others ... know info about my computer .. and how can they hack it ?
thanxxx
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Question by:3ezz
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12 Comments
 
LVL 21

Expert Comment

by:jvuz
ID: 12380014
0
 
LVL 5

Expert Comment

by:Big5250
ID: 12380032
Get a firewall, quickly.  Not only can people see the info about your machine, more than likely the machine can be hijacked.

We cannot explain on this site how to hack, just ways to prevent being hacked.  So, I would again suggest getting a firewall, or install some freeware or paid firewall software for your machine.

Example:

www.zonealarm.com

hth
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LVL 21

Expert Comment

by:jvuz
ID: 12380090
0
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LVL 5

Expert Comment

by:SKULLS_Hawk
ID: 12380153
Another good idea in terms of security is to make sure you run windows updates, to close any security holes.  

There are many firewalls out there, including one in Windows XP and XP service pack 2.  The default windows ones aren't brilliant but they are better than nothing.

Also if you do get one, which as you can see if HIGHLY recommended, make sure to read the documentation, as the firewall will make changes to your system that is likely to cause you problems.  You may need to open specific ports for some of your programs.  EG. Gaming.

To answer your question directly,  how dangerous,  the simple answer is VERY.
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LVL 8

Expert Comment

by:Marakush
ID: 12380248
3ezz,

That's a very broad question... Let me try to address it without going nuts and getting yelled at here :)

Okay depending on your operating system and security patches installed on said OS, there are vuniablities. Which can be exploited using various methods. The exploits have a common ground, open ports on your computer.

Now lets say there is an exploit for Microsoft SQL server (TCP Port 1433 / UDP 1434) Now there was a little virus a few years ago that took advantage of the fact that a fair percentage of Admins used a blank password for the 'sa' account within SQL server.  The virus spread using port 1433 and a blank 'sa' password and preaty much hose a good percentage of the internet because this port was open.

Now that is just an example of an old exploit that I hope (god I hope admins have blocked and used passwords) gives you an example of why you should only have ports open that you are activatily using.

Now if you get a cheapo router like a netgear or linksys, you can use a function like port triggering that will open up ports on demand, lets say you have a game you play online (Star craft) when you start the game and go online with it it will open port 6112 out and when that happens the router will open port 6112 into your computer so you can play the game.

Anyway hope this helps describe why you need to put something infront of your computer connection to the Internet.  s people here have suggested you really should protect your connection using something if you can't spring for a router (Under 50$ in most places and online) you should at least use a software firewall.

Marakush
0
 
LVL 8

Expert Comment

by:holger12345
ID: 12380793
When you have an open port that means you have a program running at your computer, that is listening to requests from the outside - so that it can obey the rules of it's functionality. Every prog normally uses it's own standard port, viruses/trojans change them (as they don't wanna be detected). Since you normally never start these listeners yourself, you should prevent them from allowing easy access for the outside world, that means you must shutdown these programs (but you can't always control all that stuff) or you'll have to simply shut these ports.
You must know, that your TCP/IP adress is like your home adress... and the ports are like doors in your house - if people know, where you live, but your doors are closed, the go away! If someone finds a door open, he must know the codewords, how to enter the passage, but in principle it is possible. So your firewall should act as a stonewall and keep the others outside, even when programs on your computer want to receive input - outsiders have to go through the wall - and that firewalldoor is controlled by YOU!

Conclusion:
1) Install a firewall!
2) No port open means, no simple (entrance) attacks from outside possible.
3) Only allow inside programs to contact the outside, when you really have wanted them to do so! Sometimes you have to open more than you think, but try to minimize the holes

Good luck
Holger
0
 
LVL 2

Expert Comment

by:whiting002
ID: 12380800
If this is a personal PC you should be fine by keeping up-to-date with the windows updates and running the firewall that comes with xp sp2.  I've had to deal with Microsoft Tech Support the past couple weeks do to a server issue and while we were waiting on a process to run the tech was telling me that Microsoft has a contest going on right now for anyone who wants to try and hack a xp machine that they setup running only the sp2 firewall.  They're offering all kinds of rewards if someone can hack it and show the company how.  I haven't searched any information for this but that is what the tech said.  Also for the most part if you are going to hack a system you will either scan for a bunch of easy computers to hack or you will target a specifc computer for a reason.  If you have a firewall running they won't hack you just to hack you they would have to have a reason.  So unless you ticking off the wrong people you shouldn't have a problem as long as you run the sp2 firewall and keep your system up-to-date.
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LVL 1

Author Comment

by:3ezz
ID: 12381108
dears ..
i do not want to have security ..
i just want to learn how can i use these open ports in other machines ..  (i means manually and without application prorams)
thank you for your fast response ..
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LVL 5

Expert Comment

by:SKULLS_Hawk
ID: 12381145
Use these ports in other machines?  That depends on what you want to do.

Sounds a little like you want hacking advice to me. ;-)

Perhaps if you can clarify what you are trying to acheive?
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LVL 4

Accepted Solution

by:
tmcguiness earned 2000 total points
ID: 12381275
There are a lot of sites you can go to that will explain the use of the different well known ports. www.iana.org/assignments/port-numbers is authoritative and might be a good place for you to get started finding out the specifics about the ports that are open on your machine.

A port that is listening though is nothing more than software that pays attention when it sees a particular port number in the TCP header. So, if you want to use an open port, you're pretty much going to have to play along with the rules of the software that is listening for that port number. If you do otherwise, you'll either be ignored, have unpredictable results, or break something.

There are tools you can play with to tinker with ports. If you want you can use telnet. Just telnet to a device and specify the port number after the host name or address. Like telnet foo.com 80. If you did this and hit your enter key a few times, you'd probably get an http header back telling you the type of web server foo is running.

There are other tools that are a little more sophisticated like netcat and others that I'll leave for you to look into.

What you really need to do though is determine what you are trying to do and find the software that will support that application. Computers are just machines and ports are just programs. Your not going to have much luck forcing your will on them.
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LVL 8

Expert Comment

by:holger12345
ID: 12381725
>> Title: how dangrous to have open TCP ports ??
>> just want to learn how can i use these open ports in other machines ..

Why don't you ask the right question before we can think about an answer?
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LVL 1

Author Comment

by:3ezz
ID: 12383382
every body understand the question except you .. what does that mean ..
you are very special dear.. stupid
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