This message was posted to another list and I asked Lance and he said I could send it out here as well.
This may help some of the people with speed problems running nmap. steve ############################################# Not sure if this is commonly known, however I wanted to share something I've learned with nmap. As part of my job, I often do a great deal of scanning of firewalls, or scanning through firewalls. This can be VERY TIME consuming, as you get no response for each probe, a full scan (all 65000+ ports) of a firewall used to average me 3200 seconds. While teaching a class we were able to DRAMATCALLY reduce this for TCP scans to average 840 seconds. Using the following command line options --max_rtt_timeout 50 --max-parallelism 100 By reducing rtt_timeout to 50, we DRAMATICALLY reduced the time for scanning, however, this is when the target is only 2 hops away, you may experience dropped packets if there are more hops. I can say this with a high degree with confidence, as we had 8 different systems probe all 65000+ TCP ports, all averaging around 840-850 seconds per scan. By changing the rtt_timeout to 10, we got the time down to 350+, but you are really pushing it. Increasing the number of parrallel scans beyond 100 seemed to have no improvement. Unfortunatelyl, UDP still took MUCH LONGER, averaging 2000-3000 seconds perscan :-0 Just thought I would share this tidbit, for those of you who have waited to firewall scans :) -- Lance Spitzner http://www.honeynet.org - [EMAIL PROTECTED]: general discussions about Nessus. * To unsubscribe, send a mail to [EMAIL PROTECTED] with "unsubscribe nessus" in the body.
