Penetration Testing mailing list archives
Re: nmap udp scan time
From: jpecou () gmail com
Date: 26 Oct 2007 19:24:43 -0000
Kevin, I believe UDP scans can take such a long time because UNLIKE TCP scans UDP does not rely on a handshake and therefore their is no STATE assigned to a connection. If your scanning a firewalled machine that is not replying to the UDP packets that are sent to CLOSED ports then I believe your scan will take quite sometime to complete. With TCP you will be sending out a SYN packet that will only wait a short time frame before determining that that port is either Open, Closed, or Filtered. UDP is a less reliable scan which I believe is based on correlating results. It is hard for a UDP scan to determine if a port is Open|Filtered unless it discovers a true Closed port. So your scanner may be sitting around waiting for responses from ports that will never respond. Next time you scan try using a protocol analyzer like Wireshark/Ethereal to see if you are getting responses from the majority of ports you have scanned. This is just my understanding of differences in scan types an d I apologize if any of my statements are incorrect. ------------------------------------------------------------------------ This list is sponsored by: Cenzic Need to secure your web apps NOW? Cenzic finds more, "real" vulnerabilities fast. Click to try it, buy it or download a solution FREE today! http://www.cenzic.com/downloads ------------------------------------------------------------------------
Current thread:
- nmap udp scan time Kevin Mc Grath (Oct 26)
- Re: nmap udp scan time Gleb Paharenko (Oct 29)
- RE: nmap udp scan time Strykar (Oct 29)
- Re: nmap udp scan time Anders Thulin (Oct 29)
- RE: nmap udp scan time John Forristel (SunGard-Chico) (Oct 29)
- Re: nmap udp scan time Fyodor (Oct 30)
- <Possible follow-ups>
- Re: nmap udp scan time jpecou (Oct 29)
- Re: nmap udp scan time jason_jones98 (Oct 30)