Let Loose the Pings

Photo Courtesy Sean Hawkey
Our lab contains this very expensive hardware based traffic generator. This device is not easily configured and can be a pain to used. But once you set it up the device can generate any type of traffic and network transactions. The problem comes in that somebody changed the admin password, and nobody knew the new one. Now the device can still be used without the admin password however you cannot configure the interfaces without it. We were in a time crunch and needed to perform a simple network test, and did not have time to reset the password. The problem came in that whoever reset the admin password changed the IP address on the interface. The problem is we needed to figure out the IP address of the interface in order to configure the test. Easy, there are only 4 billion addresses to ping, by the way the device was set to respond to pings. Well it gets better we knew the address was 10.x.0.11, so we only have to try at the most 255 addresses. Well my co-worker starts pinging one at a time, and i think he is crazy, we are programmers, lets write a quick vbscript and run it with wsh. Basically this script runs through 10.0-255.0.11 addresses and parses the output from the ping. If it receives a Reply then the script prints that address and exits. The script could be modified with more loops to go through more addresses however the script is slow because it only processes one ping at a time, if you need more pings a c program would work much faster.

Basic operation - for loop going through 0-255 (each number is output the screen), a variable is used to build the ping statement, a shell is created for the ping command to be executed, the output from the ping command which is in stdout is parsed looking for the word Reply, if Reply is found then the ip address is echoed to the screen and the script exits. When running this script ensure you use cscript or you will have windows popping up for each ping. This script worked extremely well, we took a break while the script ran and came back and the magic number was 42 - imagine that.

for i = 0 to 255
y = 1
wscript.echo i
a = "ping -n 1 10." & i & ".0.11"
Set objShell = CreateObject("WScript.Shell")
Set objWshScriptExec = objShell.Exec(a)
Set objStdOut = objWshScriptExec.StdOut
While Not objStdOut.AtEndOfStream
strLine = objStdOut.ReadLine
if mid(strLine,1,5) = "Reply" then
y = y + 1
end if
Wend
if y > 1 then
wscript.echo a
exit for
end if
next