I take it everyone has seen the latest advisory from ISC? Anyone got a idea exactly where the problem is, or got an exploit? ISC do say that an exploit isn't available, but it's been a few hours since then :-) Dom - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Dom De Vitto Tel. 07855 805 271 http://www.devitto.com mailto:domat_private - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -----Original Message----- From: Fyodor [mailto:fyodorat_private] Sent: Monday, November 04, 2002 6:08 PM To: Frank Knobbe Cc: Michael Katz; vuln-devat_private; d_fenceat_private Subject: Re: Firewall bypassing tool On Sun, Nov 03, 2002 at 05:02:49PM -0600, Frank Knobbe wrote: > On Fri, 2002-11-01 at 13:38, Michael Katz wrote: > > At 11/1/2002 03:28 AM, d_fence wrote: > > > > One of the options for scanning is -sF, which will send SYN-FIN > > packets. You can also use -sA, which will send SYN-ACK packets. > > I was about to post the same, but thought I validate first. To me it > seemed that nmap sends a packet with the FIN flag set. I did not see > the SYN flag set in addition to FIN, so nmap is not an answer to his > question. Nmap has an undocumented --scanflags option which allows you to specify arbitrary flags using the flag names or a number. Thus a SYN-FIN scan can be done as follows: felix~#nmap -sS --scanflags SYNFIN -O db Starting nmap V. 3.10ALPHA3 ( www.insecure.org/nmap/ ) Interesting ports on db.yuma.net (192.168.0.4): (The 1601 ports scanned but not shown below are in state: closed) Port State Service 22/tcp open ssh 111/tcp open sunrpc 1024/tcp open kdm Remote operating system guess: Linux Kernel 2.4.0 - 2.5.20 Uptime 58.471 days (since Fri Sep 6 23:45:12 2002) Nmap run completed -- 1 IP address (1 host up) scanned in 10.651 seconds Note that "-sS" causes this scan to use "SYN Scan" semantics (eg treating SYN|ACK responses as open ports). For FIN scan semantics (dropped packets signify open ports, RST for closed ones) just specify "-sF" instead. Cheers, Fyodor
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