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Can hackers see data going to and from my computer?

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Summary: In some instances, it might be possible for hackers to see data going to and from one's computer. Sometimes it matters, but sometimes it doesn't.

I've heard that instant messages through AOL/Yahoo/MSN can be read by hackers that "sniff" the messages leaving my network. Is this true?

Yes.

But most of the time it doesn't matter. On the other hand, there are times when you really need to be careful.

Data traveling on a network such as the internet can be seen by many other machines. Local machines connected via a hub, for example, all see the data being sent to and from all the other machines connected to the same hub. As the data travels the internet, it's quite possible that other machines on the network can also see the data.

Sounds scary.

The good news is that's really hard find data transmitted to and from a specific machine unless you're on the same network segment. For example if you're connected to the internet via DSL, other machines sharing your DSL could watch your traffic, but machines out on the internet would have an extremely difficult time tracking it down.

It's not something I worry about much.

However, there is a scenario that you should be very aware of.

Wireless network access points operate much like a hub. Any wireless adapter in range can see all of the network traffic in the area.

Visited any wireless hotspots lately? Anyone in the coffee shop, library, other public places, or even just outside on the street or a nearby building could be sniffing your traffic.

So, what to do?

Well, for one thing, make sure that any sensitive web surfing you might choose to do - such as banking or on-line shopping - is always done via a secure connection. Even better - wait until you're home to do those things.

Email is particularly sensitive. For example it's not difficult to sniff your email account information when downloading email via a normal POP3 account, or sending via SMTP. Web interfaces that use "https" secure connections are actually safer.

And if your wireless network at home is within range of other houses, the street, or other public areas, make sure you're at least using 128bit WEP to ensure that the data that would be visible is encrypted.

Related:

Article 2666 | Posted February 24, 2005

Recent Comments
38 Comments

I have been talking to who I thought was a friend for the past 2 months and then he popped up and said that he wasnt really that person. He was just using his screen name and myspace. But this guy has been sending me my friends pics and information about his work in the military. Is that possible to really be able to have acess to someones whole computer like that?

Posted by: Sheena at July 9, 2008 7:11 AM

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Absolutely. If your (real) friend was careless and somehow
let his account information be stolen, this kind of thing
could easily happen. And it does.

That's why people like me keep harping on keeping your
computer secure, choosing good passwords, and all the other
habits we should develop to stay safe.

Leo


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Posted by: Leo at July 9, 2008 1:38 PM

Hi Leo,
I recieved an e-mail where I was selling something on online (Craiglist). By stupid of my part (sorry for the word)I gave the person my address and name. After I did that I noticed that it was an Scam. What the person can do with my name and address?
thank you for your advise.
Tony

Posted by: Antonio Liriano at August 27, 2008 4:32 PM

Can someone hack into my computer and put a screensaver on my computer?

Posted by: Alice at September 10, 2008 4:22 PM

Does a police officer or police dept. have access to hack into someone's computer?

Depends on where you live, but in short: yes, if they have evidence that a crime has been committed, and they get an order from the court.

-Leo

Posted by: Alice at September 10, 2008 5:12 PM

Me and my roommate are sharing the wireless internet connection(secured WPA- personal).Can my room mate see what I am doing on the internet like I use Skype to talk to my girlfrn,so can he see what we are talking about and can he see the skype video too.If he can,how can I secure it from my roommate.

Posted by: John Cooper at September 23, 2008 1:27 PM

can some one hack in2 someones else computer throgh a virus ?

Yes,
- Leo
13-Oct-2008

Posted by: swan at October 13, 2008 5:41 AM

I would like to know if there is anyway to check my laptop to know if has a worm or something inside that allows somebody else outside there to receive all the moves I do in my laptop.
There is a very small window that appears and dissapears at the bottom of my machine, where the bar of programs is and shows the applications that are open. This small window that shows and then disappear began to appear like 6 months ago and I am thinking that somebody installed, through an email I received, some kind of application that hacks my emails and also my internet moves.
Is it possible that Norton Antivirus can capture that worm?
Thank you.

Posted by: Miracles at October 18, 2008 3:02 PM

Can a hacker steal any files from my computer?

Depends entirely on how secure you are. If you've done nothing for security then the answer is absolutely yes. See this article: Internet Safety: How do I keep my computer safe on the internet?
- Leo
20-Oct-2008

Posted by: Kristell at October 19, 2008 7:53 PM

dear leo,
can someone hack into my laptop history and sms on the phones as i was told there is a software which cost £200 over the net. Please advise

Posted by: Karina Bat at December 21, 2008 3:51 PM

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