16 May 2008 | 12,237 views

Xprobe2 – Active OS Fingerprinting Tool

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Sometimes I wonder to myself have I mentioned a certain tool on the site, usually one of my favourites…often I search the site to find I have never posted about it.

It just goes to show how we often overlook some of the more ‘obvious’ choices, and to many people they may not be that obvious. I’ll be going through the tools I use and posting them up here if I haven’t already.

Anyway one of the stock tools for any pen-tester is Xprobe usually known now as Xprobe2 – some of it’s logic has been absorbed into nmap and it’s basically an active OS fingerprinting tool meaning it sends actual data to the machine it’s fingerprinting rather than a passive tool like p0f which just listens.

Xprobe2 is a remote, active OS fingerprinting tool, the features are as below:

  • Port scanning is now available through the usage of the -T (TCP) and -U (UDP) command line option
  • Added the -B command line option (‘blind port guess’) used for searching an open TCP port among the following ports: 80,21, 25, 22, 139
  • Include XSD schema with distribution and make our XML comply with that XSD
  • loopback (lo) is supported

You can read more on Xprobe2 and what it does here:

Intrusion Detection FAQ: What is XProbe?

Download Xprobe2 here:


Or read more here.


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10 Responses to “Xprobe2 – Active OS Fingerprinting Tool”

  1. matt 16 May 2008 at 9:25 pm Permalink

    Sounds like a very useful tool. Would be nice to see all of these features combined with nmap. …maybe a new project for myself. Thanks for the article!

  2. Jinesh 19 May 2008 at 1:39 pm Permalink

    Words are not enough to describe this tool.

  3. Chris 20 May 2008 at 9:32 am Permalink

    I must politely disagree with Matt here. Personally I don’t use nmap at all, but I very much agree with the unix philosophy of one tool for one type of purpose. nmap is already doing too much, it should in my opinion do less.

    Let xprobe2 stay the way it is, and try and slim nmap down a bit. What they should do with nmap is improve their UDP-scanning. Integrate a payload system, like the one found in unicornscan. Also they should stop doing automatic flow-control. It just messes up badly on larger networks. You need to be able to calculate efficiency and time.

    My two cents.

  4. Darknet 20 May 2008 at 9:59 am Permalink

    Chris: You kind of went against what you were saying there, for UDP scanning Unicornscan is better…for larger networks either Unicornscan, Scanrand or Advanced LAN Scanner. Or a paired down version of nmap with the right options. Different tools for different jobs.

  5. Chris 20 May 2008 at 10:59 am Permalink

    I did? I personally find that nmap just cannot do the job on large networks, i.e /18-. It takes too much time, and there is no way to control how it interacts with its environment.

    If we’re talking about portscanning, I include UDP/TCP for that. unicornscan does just that, it does portscanning, nothing more. For that reason I prefer unicornscan over nmap. It’s not however to say I think nmap is bad, for certain things it performs very well. It all comes down to the job, purpose and the tester. The tester should be comfortable with all the tools he decide to use, they are never a replacement for good understanding of x.y.z.

    If I contradicted myself, that was not my intention. (And I still fail to see how I did!)

    – Chris

  6. Darknet 20 May 2008 at 4:00 pm Permalink

    Chris: Well it depends how you look at it, it’s very subjective. For me nmap started out as a decent TCP connect scanner and evolved from there, the main featureset is on the TCP side – it’s definitely not a competent UDP like Unicornscan is. Yes Unicorn does TCP as well and it does it better for large networks but I still find nmap better for TCP investigation and trickery (idle scans, decoys, banner grabbing etc). For me saying it should be better at UDP scanning is the opposite of one tool for one purpose.

  7. Erik 21 May 2008 at 5:09 pm Permalink

    The only things about active OS fingerprinting is that it can be done from any network as long as the fingerprinted host is reachable. Apart from that I really prefer doing passive OS fingerprinting.

    Is there by the way any point in doing OS fingerprinting based on UDP packets? My feeling is that they don’t hold enough information in order to fingerprint a host properly. A much better fingerprinting method is to look at DHCP packets since they reveal a lot about the host. The good thing with DHCP is also that it is broadcast, so it’s perfect for doing passively. In fact the new version of NetworkMiner [ http://networkminer.wiki.sourceforge.net/NetworkMiner ] supports passive OS fingerprinting using both TCP and DHCP fingerprinting.

    I haven’t tried unicornscan though, it also seems to have some passive OS fingerprinting functionality.

  8. Darknet 21 May 2008 at 5:41 pm Permalink

    Erik: I agree, due to the nature of UDP packets they have very little overhead and therefore very little useful info. DHCP packets and anything broadcast by Windows machines is useful. NetworkMiner is a neat tool we have covered it here before, still the best for passive OS fingerprinting is p0f – I haven’t yet covered that here but will shortly. The active OS fingerprinting in nmap is pretty decent too, I haven’t tried any of those features in Unicornscan yet.

  9. Xnih 28 November 2008 at 2:47 am Permalink

    Darknet: I’ll jump on the bandwagon with Erik, but that is just because his programs uses the DHCP fingerprinting from my own program Satori [ http://myweb.cableone.net/xnih ]. p0f does a decent job of passive os fingerprinting in the area of syn and syn/ack packets, but does nothing with DHCP, ICMP, CDP, IPX/SAP, etc, nor has it been updated in years.

  10. Sifmole 9 January 2009 at 5:14 pm Permalink

    One of my problems with xprobe2 is that the only fingerprinting database I can find is from 11 July 2005. Do any of you know where you can find updated databases?