Security Basics mailing list archives
Re: Advice on Fastest NMAP Scan
From: Ghaith Nasrawi <libero () aucegypt edu>
Date: Fri, 29 Oct 2004 02:44:13 +0000
when I try nmap scanning within Nessus, it just take ages to finish the initial scanning process. I think nessus developers should make of the new modifications to nmap in order to speed up the whole process of assessing vuln. targets. On Tue, 2004-10-26 at 23:05, Fyodor wrote:
On Tue, Oct 26, 2004 at 09:58:50AM -0500, Mogren, Jack L. wrote:Here's what I've come up with so far. nmap -O -T4 -PE -F --osscan_limit -oX /home/security/test.xml -iL /home/security/ip_addresses.txt Any comments or suggestions?First off, make sure that you are using Nmap 3.75. Nmap 3.70 included a complete port scan engine rewrite for better performance (among other advantages) and then 3.75 tweaked it to be even better. You can obtain Nmap 3.75 from http://www.insecure.org/nmap . Since you know your network, you may be able to help Nmap by setting a maximum retransmission timeout. Are you scanning over multiple continents, or just a local network? If you can assume that responses won't take more than 100ms, add --max_rtt_timeout 100 for a big speed boost. Also, use a large host group such as --min_hostgroup 128 so that many hosts are scanned in parallel. Play with the numbers a bit to figure out what works best on your particular network. You could also consider a custom nmap-services file with just a couple hundred of the most common TCP ports. Even the -F option still scans more than 1200 ports by default. I would be interested to hear how it goes. If you find that it is too slow for your needs, let me know. I am working on a performance chapter of my upcoming O'Reilly Nmap book, so I have studied several such large network situations. A class B and several class C's shouldn't be any problem at all for regular scanning. Your "entire private address space" make take a while, depending on your setup. Scanning 10.0.0.0/8 is 16 million IPs, so don't expect it to complete during lunch. Some of the tools that claim incredibly speeds don't even handle retransmissions or other reliability requirements. I hope this helps, Fyodor
Current thread:
- Advice on Fastest NMAP Scan Mogren, Jack L. (Oct 26)
- Re: Advice on Fastest NMAP Scan robert (Oct 26)
- Re: Advice on Fastest NMAP Scan Fyodor (Oct 26)
- Re: Advice on Fastest NMAP Scan GuidoZ (Oct 28)
- Re: Advice on Fastest NMAP Scan Ghaith Nasrawi (Oct 29)
- Re: Advice on Fastest NMAP Scan Gabriel Orozco (Oct 27)
- RE: Advice on Fastest NMAP Scan Andy Cuff (Oct 27)