Finding Open Ports on a LAN

[mbaker33]

Hey all,

First off, let me just say, I am not trying to obtain information that I will later turn around and use to hack with. I am a member of my company's IT department and we just want to be able to type in a certain port number (i.e. 2209 or 7834) and return all of the computers that have this open port. This is basically so we can see if someone has a certain Server application running like SQL Server or MySQL or something like that. We know it is happening, but the people that are doing it do a pretty good job at hiding it, but you can't hide a port number. If anyone has some information that would be helpful please post. Thank you for your time.

Mark

[JordanChris]

You are effectively doing a TELNET <computername> <portnumber>.

You could do this using a DOS command sent from the VB app.
Or you could look up what Telnet is doiing with Winsock from places like this forum or www.winsockvb.com

[mbaker33]

duhh.....I knew it was something simple. Isn't it always?? Thanks a bunch, the telnet idea works great, now I just need to capture the data coming back to see if it connected or not.

Thanks again.

[mbaker33]

Ok guys,

I am thinking the best way to do this will be to Shell(telnet.exe IP Port) but I am not sure how to capture the returned text. Anyone have any ideas??

[JordanChris]

You need to shell Command.com to get output re-direction.

I.e.:

Shell "Command.com /c Telnet.exe 10.44.23.123 80 > c:\temp\Results.txt"

Then you can open and look at the resulting file.

But whether this will work with Telnet, I am not sure. You might find that the Telnet.EXE application has its own output stream. Test it on a DOS window first.....