Snort mailing list archives
Re: How many ports is considered a portsweep/portscan?
From: Matt Olney <molney () sourcefire com>
Date: Thu, 18 Mar 2010 09:39:10 -0400
Have you tried this? 3. Make use of the Priority Count, Connection Count, IP Count, Port Count, IP range, and Port range to determine false positives. The portscan alert details are vital in determining the scope of a portscan and also the confidence of the portscan. In the future, we hope to automate much of this analysis in assigning a scope level and confidence level, but for now the user must manually do this. The easiest way to determine false positives is through simple ratio estimations. The following is a list of ratios to estimate and the associated values that indicate a legimite scan and not a false positive. Connection Count / IP Count: This ratio indicates an estimated average of connections per IP. For portscans, this ratio should be high, the higher the better. For portsweeps, this ratio should be low. Port Count / IP Count: This ratio indicates an estimated average of ports connected to per IP. For portscans, this ratio should be high and indicates that the scanned host's ports were connected to by fewer IPs. For portsweeps, this ratio should be low, indicating that the scanning host connected to few ports but on many hosts. Connection Count / Port Count: This ratio indicates an estimated average of connections per port. For portscans, this ratio should be low. This indicates that each connection was to a different port. For portsweeps, this ratio should be high. This indicates that there were many connections to the same port. The reason that Priority Count is not included, is because the priority count is included in the connection count and the above comparisons take that into consideration. The Priority Count play an important role in tuning because the higher the priority count the more likely it is a real portscan or portsweep (unless the host is firewalled). On Thu, Mar 18, 2010 at 9:10 AM, James Lay <jlay () slave-tothe-box net> wrote:
Subject pretty much says it all...there are certain machines that I want to be able to detect a portsweep or scan, but not when they scan say 4 or 5 ports like booting up with netbios checking out other machines on a network (I think that’s why I’m seeing these FP’s). Sfportscan is set to low, but I’m not sure what else I can set? Thanks all. James ------------------------------------------------------------------------------ Download Intel® Parallel Studio Eval Try the new software tools for yourself. Speed compiling, find bugs proactively, and fine-tune applications for parallel performance. See why Intel Parallel Studio got high marks during beta. http://p.sf.net/sfu/intel-sw-dev _______________________________________________ Snort-users mailing list Snort-users () lists sourceforge net Go to this URL to change user options or unsubscribe: https://lists.sourceforge.net/lists/listinfo/snort-users Snort-users list archive: http://www.geocrawler.com/redir-sf.php3?list=snort-users
------------------------------------------------------------------------------ Download Intel® Parallel Studio Eval Try the new software tools for yourself. Speed compiling, find bugs proactively, and fine-tune applications for parallel performance. See why Intel Parallel Studio got high marks during beta. http://p.sf.net/sfu/intel-sw-dev
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Current thread:
- How many ports is considered a portsweep/portscan? James Lay (Mar 18)
- Re: How many ports is considered a portsweep/portscan? Matt Olney (Mar 18)
- Re: How many ports is considered a portsweep/portscan? James Lay (Mar 18)
- Re: How many ports is considered a portsweep/portscan? Nerijus Krukauskas (Mar 18)
- Re: How many ports is considered a portsweep/portscan? Russ Combs (Mar 19)
- Re: How many ports is considered a portsweep/portscan? Nerijus Krukauskas (Mar 24)
- Re: How many ports is considered a portsweep/portscan? Joel Esler (Mar 24)
- Re: How many ports is considered a portsweep/portscan? Ryan Jordan (Mar 24)
- Re: How many ports is considered a portsweep/portscan? Joel Esler (Mar 24)
- Re: How many ports is considered a portsweep/portscan? Nerijus Krukauskas (Mar 24)
- Re: How many ports is considered a portsweep/portscan? James Lay (Mar 18)
- Re: How many ports is considered a portsweep/portscan? Matt Olney (Mar 18)