All files are for educational and/or historic purposes only. [back to library]

When you first turn on you computer (BEFORE DIALING INTO YOUR ISP),
open a MS-DOS Prompt window (start/programs MS-DOS Prompt).
Then type netstat -arn and press the Enter key.
Your screen should display the following (without the dotted lines
which I added for clarification).

Active Routes:

  Network Address          Netmask  Gateway Address        Interface  Metric      1      1

Route Table

Active Connections

  Proto  Local Address          Foreign Address        State


If you see anything else, there might be a problem (more on that later).
Now dial into your ISP, once you are connected;
go back to the MS-DOS Prompt and run the same command as before
netstat -arn, this time it will look similar to the following (without
dotted lines).


Active Routes:

  Network Address          Netmask  Gateway Address        Interface  Metric
      1      1      1      1      1      1      1

Route Table

Active Connections

  Proto  Local Address          Foreign Address        State
  TCP                  LISTENING
  TCP              LISTENING
  TCP              LISTENING
  TCP              LISTENING
  UDP      *:*       


What you are seeing in the first section (Active Routes) under the heading of
Network Address are some additional lines. The only ones that should be there
are ones belonging to your ISP (more on that later). In the second section
(Route Table) under Local Address you are seeing the IP address that your ISP
assigned you (in this example

The numbers are divided into four dot notations, the first three should be
the same for both sets, while in this case the .70 is the unique number
assigned for THIS session. Next time you dial in that number will more than
likely be different.

To make sure that the first three notation are as they should be, we will run
one more command from the MS-DOS window.
From the MS-DOS Prompt type tracert / or .net
or whatever it ends in. Following is an example of the output you should see.


Tracing route to / []over a maximum of 30 hops: 
1  128 ms  2084 ms  102 ms [] 
2  115 ms  188 ms  117 ms [] 
3  108 ms  116 ms  119 ms []
Trace complete.


You will see that on lines with the 1 and 2 the first three notations of the
address match with what we saw above, which is a good thing. If it does not,
then some further investigation is needed.

If everything matches like above, you can almost breath easier. Another thing
which should you should check is programs launched during startup. To find
these, Click start/programs/startup, look at what shows up. You should be
able to recognize everything there, if not, once again more investigation is


Now just because everything reported out like we expected (and demonstrated
above) we still are not out of the woods. How is this so, you ask? Do you use
Netmeeting? Do you get on IRC (Internet Relay Chat)? Or any other program
that makes use of the Internet. Have you every recieved an email with an
attachment that ended in .exe? The list goes on and on, basically anything
that you run could have become infected with a trojan. What this means, is
the program appears to do what you expect, but also does just a little more.
This little more could be blasting or one of the other sites that
CNNlive was talking about.

What can you do? Well some anti-virus software will detect some trojans.
Another (tedious) thing is to start each of these "extra" Internet programs
one at a time and go through the last two steps above, looking at the routes
and connection the program uses. However, the tricky part will be figuring
out where to tracert to in order to find out if the addresses you see in
step 2 are "safe" or not. I should forewarn you, that running tracert after
tracert, after tracert might be considered "improper" by your ISP. The steps
outlined above may not work exactly as I have stated depending upon your ISP,
but with a true ISP it should work. Finally, this advise comes with NO
warranty and by following my "hints' you implicitly release me from ANY and
ALL liability which you may incur.

 Other options

Display protocol statistics and current TCP/IP network connections.
Netstat [-a] [-e] [-n] [-s] [-p proto] [-r] [intervals]

-a.. Display all connections and listening ports.
-e.. Display Ethernet statistics. This may be combined with the -s option.
-n.. Diplays address and port numbers in the numerical form.
-p proto..Shows connections for the protocol specified by proto; proto may be
TCP or UDP. If used with the -s option to display per-protocol statistics,
proto may be TCP, UDP, of IP.
-r.. Display the routing table.
-s.. Display per-protocol statistics. By default, statistics are shown for TCP
UDP and IP; the -p option may be used to specify a subset of the default
interval..Redisplay selected statistics, pausing intervals seconds between each
display. If omitted. netstat will print the current configuration information