Is there a way to know if someone has accessed (through the internet) your?

Question

computer (without your permission) and copied some of your files.

Thanks for the info!

A few days ago my Firewall failed, and I didn't re-start my computer. When I initiated shut it down two hours later I received a warning that 4 users we're still connected to my computer, and that shutting it down would leave them out as well. :(

Sorry for the typos.

BTW: I don't have any P2P programs installed on my computer.

EDIT: The warning came in a Windows box, not from my firewall program.

Like I said, my firewall was down.

Answer 1

You already know that, they have. They were connected to your computer. They were in your computer.

There is no way to know what if any files they may have copied.
They probably installed viruses and spyware on your computer. You must remove it. It is quite possible malware disabled your firewall to begin with.

Never run your computer without a Firewall and active (full-time) spyware and adware protection.

Read carefully:
http://wiki.castlecops.com/Malware_Removal_and_Prevention:_Overview
http://wiki.castlecops.com/Malware_Prevention:_Prevent_Re-infection
http://www.castlecops.com/f67-Hijackthis_Spyware_Viruses_Worms_Trojans_Oh_My.html
http://www.castlecops.com/t102301-Hijackthis_Guidelines_Read_Before_Posting.html

Follow all steps on this web page:
http://www.techsupportforum.com/security-center/hijackthis-log-help/15968-please-read-before-posting-hijackthis-log.html

Add the following to Step 2
Run “immunize” in Spybot Search in Destroy in addition to the scan.

Malicious Software Removal Tool (run “full scan”)
http://www.microsoft.com/security/malwareremove/default.mspx

Microsoft OneCare “full scan”
http://safety.live.com/site/en-US/default.htm

SpywareBlaster update + enable all protection
http://www.javacoolsoftware.com/spywareblaster.html

SUPERAntiSpyware Free Version update + full scan
http://www.superantispyware.com/

PC Pitstop full tests.
http://www.pcpitstop.com/

Rootkit revealer
Close all programs first and then run.
http://www.microsoft.com/technet/sysinternals/utilities/RootkitRevealer.mspx
Save the results. Do nothing at this time with the results! Not all results will be malware! Google each result.

Install Windows Defender, set to update and run a full scan weekly
http://www.microsoft.com/athome/security/spyware/software/default.mspx

In Step 5

Windows update: Run in custom mode, install everything, repeat until nothing is left.
http://update.microsoft.com/microsoftupdate/v6/default.aspx?ln=en-us


Prevention: Weekly or as required:
Update you full time anti-virus and full time anti-spyware programs and run a full scan.
Run Microsoft OneCare “full scan”
Ad-Aware SE Personal update + immunize + check for problems
SpywareBlaster update + enable all protection
SUPERAntiSpyware Free Version update + full scan
Spybot - Search & Destroy update + full scan
PC Pitstop “running programs” Are there any new ones? Do you know what each does?
http://www.pcpitstop.com/
Examine your list of firewall exceptions. Any new ones? Do you know what each is for? An exception allows a program unrestricted access through your firewall. Do not open ports in your firewall and never leave the port open. An open port creates a hole through your firewall that anyone can exploit to control your computer.
Check you Program List in Ad/Remove programs. Any new programs? Do you know what each is for?

Optional:
Install CCleaner, set to run when computer starts (on a clean system only)
http://www.ccleaner.com/

Answer 2

If you have more than one user account on your computer then its possible that they were active. Firewalls normally dont warm you in cases where someone was connected to your computer. If you have a network based firewall then maybe but besides that, i havent seen situations that it has given that warning. Also you can find software that scans your ports and see who and what is connected to a port at a certain time.