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My Internet connection has been slow lately, and I think it might be a possible attack. A friend has told me to use Wireshark, but it is a big install, and I do not have the time to learn how to use it. Is there an easier way to see all the connections on my PC so I can take further action?

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Wow I had no idea Wireshark had grown to between 17 and 32 MB depending on your system. I endorse the Sysinternals mentioned. –  dlamblin Jul 23 '09 at 6:37
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4 Answers

up vote 15 down vote accepted

You are looking for the netstat command. This command should provide what you're looking for:

netstat -a

if you would also like to see what programs are using the specified ports you can use:

netstat -b

to use the netstat program:

  • Go to the start menu (or press Win + r and skip to step 3)
  • If on XP, click "Run", If on vista or later, search for cmd in the search box and skip to step 4.
  • type cmd
  • after cmd opens, type netstat -a
  • a list of all open connections with their ports will be displayed

more info about netstat:

C:\Documents and Settings\Administrator>netstat /?

Displays protocol statistics and current TCP/IP network connections.

NETSTAT [-a] [-b] [-e] [-n] [-o] [-p proto] [-r] [-s] [-v] [interval]

-a          Displays all connections and listening ports.
-b          Displays the executable involved in creating each connection
    		or
    		listening port. In some cases well-known executables host
    		multiple independent components, and in these cases the
    		sequence of components involved in creating the connection
    		or listening port is displayed. In this case the executable
    		name is in [] at the bottom, on top is the component it 
    		called,
    		and so forth until TCP/IP was reached. Note that this option
    		can be time-consuming and will fail unless you have 
    		sufficient
    		permissions.
-e            Displays Ethernet statistics. This may be combined with the
    		-s
    		option.
-n          Displays addresses and port numbers in numerical form.
-o          Displays the owning process ID associated with each connection.
-p proto    Shows connections for the protocol specified by proto; proto
        may be any of: TCP, UDP, TCPv6, or UDPv6.  If used with 
            the -s option to display per-protocol statistics, proto may be
            any of:
    	IP, IPv6, ICMP, ICMPv6, TCP, TCPv6, UDP, or UDPv6.
-r          Displays the routing table.
-s          Displays per-protocol statistics.  By default, statistics are
    		shown for IP, IPv6, ICMP, ICMPv6, TCP, TCPv6, UDP, and UDPv6;
    		the -p option may be used to specify a subset of the default.
-v          When used in conjunction with -b, will display sequence of
    		components involved in creating the connection or listening
    		port for all executables.
interval    Redisplays selected statistics, pausing interval seconds
    		between each display.  Press CTRL+C to stop redisplaying
    		statistics.  If omitted, netstat will print the current
    		configuration information once.
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+1 this is the easiest way, nothing to download or install. –  demetri Jul 23 '09 at 3:59
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Note, you can also just press Win+R to open the run box. Also, in Vista/7, you can just search 'cmd' in the start menu. –  Jared Harley Jul 23 '09 at 6:26
    
Thanks! Never even thought of that, edited accordingly. My thinkpad doesn't even have a windows key :) –  John T Jul 23 '09 at 6:41
    
Note that you have to run the command prompt with elevated rights to be able to use -b on Vista, Win7. –  Henning Jul 23 '09 at 10:06
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Sysinternals TCPView

I would also recommend running Autoruns and Process Explorer, also in the Sysinternals Suite to help diagnose your problem.

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Prio (http://www.prnwatch.com/prio.html) can provide, as part of the Windows Task Manager, an updating list connections with some additional context that may help you make sense of what is going on.

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Another alternative is Extensoft Free Task Manager Extensions

You can see the active ports aligned with the processes in use.

It adds a lot of functionality to the task manager and it is all contained in one area.

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