Re: NAT is present?

From: Volker Tanger (vtlists_at_wyae.de)
Date: 09/12/05

  • Next message: Aditya Deshmukh: "RE: [Full-disclosure] Exploiting a Worm"
    Date: Mon, 12 Sep 2005 23:59:03 +0200
    To: pen-test@securityfocus.com
    
    

    Greetings!

    On Mon, 12 Sep 2005 08:21:58 +0200
    "xxradar" <xxradar@radarhack.com> wrote:

    > Hey,
    > .1 seems to be a checkpoint firewall (264 is a checkpoint port)
    > I'm pretty sure that NAT rules in checkpoint can be configured to
    > behave like this on purpose (or by mistake)
    >
    > -----Original Message-----
    > From: pinoch0@gmail.com [mailto:pinoch0@gmail.com]
    >
    > *.*.*.1
    >
    > PORT STATE SERVICE
    > 264/tcp open bgmp
    > 500/tcp open isakmp
    [...]
    > All the host of the subnet seems to have http and https open but when

    Sounds a lot like a CKP FW1 with the HTTP "security server" enabled,
    which generally is allowing HTTP/HTTPS from the network you scanned
    from. This "ports-open-to-all-servers-but-does-not-work" behaviour is
    common among all proxy-based firewalls (e.g. Raptor, Symantec) or
    firewall content servers (e.g. CheckPoint, Astaro, Innominate mGuard) as
    the proxy generally has to accept all traffic and is deciding AFTER
    initial connect wether the connection is allowed.

    Technically this could be changed e.g. by packet filters that restrict
    access *before* the traffic is redirected to the proxy, but this usually
    is regarded as superfluous. Maybe the double management (PF *and* proxy
    rules) is regarded as too complicated? I am not sure about the
    performance impact of such double-filtering, but in high illegal load
    scenarios the additional PF probably is preventing the system to get
    into high(er) load compared to a "blank" proxy approach that is so
    common. I know of one technical reason for this, though: traffic
    redirection to the local proxy usually is done in the pre-routing PF
    table, while "normal" PF rules follow later in the "forward" PF rules.
    Adding PF rules in thw forward chain will never be reached of course,
    and thus it is sensible to leave such PF rules out.

    Back to CheckPoint:

    264/tcp is another hint, while nominally reserved for BGMP
    (http://netweb.usc.edu/bgmp/), here everything looks like Checkpoint.
    They are using this port for the "Check Point VPN-1 SecuRemote Topology
    Requests", which is used by the CheckPoint SecuRemote/SecureClient VPN
    client program. Which usually is using IPSec internally nowadays - and
    with it IKE/ISAKMP at port 500.

    Have you run a UDP scan too? Then you should probably find ports 500
    (IKE) and 4500 (IPSec NAT traversal for CKP) open on *.*.*.1, too if
    this is a CKP firewall/VPN.

    Bye

    Volker

    -- 
    Volker Tanger    http://www.wyae.de/volker.tanger/
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  • Next message: Aditya Deshmukh: "RE: [Full-disclosure] Exploiting a Worm"

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