WUPS - Windows UDP Port Scanner

Download v1.4 (for Windows 95 with WinSock 2.2 / 98 / ME / NT 4.0 / 2000 / XP / 2003)


An UDP port scanner for Windows. All port scanners for Windows only scanned TCP ports before I wrote this one.

Usage instructions

Download the install program file and run it. The install program is created with the freeware (for non commercial use) GkSetup written by Gero Kühn. After installation, run WUPS from the Start menu. (On Windows NT you need to be a member of the Administrators group.) It doesn't really need any explaination, except for a few things. The Delay is very important - if you set it too low the scan will fail. Another thing is that you will see no result until the scan is completely finished - there's nothing wrong, it's just the way the scanner works. Also remember the target must be specified as an IP address, not as a DNS name, and that the scanner does not check if the host is up or not before it starts the scan.


Q: When I try to install WUPS, I get an error message saying "GkWare SFX Module V1.90/Is - The data section attached to this self-extractor has been damaged. Please download this file again to get a complete copy.". What should I do now?

A: Reboot the computer and run the setup program again, then the installation should work.

Q: How does the Delay affect the result of a scan?

A: The Delay is very important for a couple of reasons. First, each port you scan will cause over 85 bytes to be transfered over the network (the exact amount depends on the kind of network). Say that your connection can only handle 5kb per second. If you scan with a delay of 10 ms, that will generate over 8.5 kb per second, and the scan will choke. This is nothing new, the same happens with TCP port scanners. The second thing is that this UDP port scanner relies on the fact that the scanned system sends back ICMP packets. A lot of machines limit the number of ICMP packets that may be sent in a specific time interval. The limit depends on the kind of system, sometimes a Delay of 50 ms will do, sometimes 500 ms will do, and sometimes you have to scan with a Delay of over 1000 ms. If you reach the systems limit, it will choke and you have to wait a while and then restart the scan. If you scan a Windows machine you can usually set the Delay as low as the network connection allows, since Windows doesn't have any ICMP limit.

Q: Which kind of packet filters will make a scan fail?

A: A packet filter that drops UDP packets from the scanner to the scanned system, and also a filter that drops ICMP packets going from the scanned system to the scanner.

Q: The result of a scan is only displayed after the scan is completed, how does this affect the scan?

A: This shouldn't be too much of a problem when the Delay has been properly set, but to set the Delay to an optimal value isn't that easy. Also there could be a problem if a packet filter stops the scan. Try to divide the range you wish to scan into several smaller, and scan them separately to minimize the effect of a possible error.

Q: What does the message "Insufficient privileges" mean?

A: It means that you are running WUPS on Windows NT but you aren't a member of the Administrators group, which is required.

Q: Why doesn't the scanner ping the target before the scan starts to check if it's up or not?

A: Because pings might be blocked out by a firewall, and I didn't have enough time to make pinging a turn on/off option.

Q: I have a question that is not covered here. Where can I get help?

A: Send me your question. I can't promise that I will have time to answer, but I'll do my best.

© Arne Vidstrom. All rights reserved.