From owner-freebsd-security Fri Aug 25 20:20:22 2000 Delivered-To: freebsd-security@freebsd.org Received: from kronus.com.br (dial-bhn-C8C0B490.bhz.zaz.com.br [200.192.180.144]) by hub.freebsd.org (Postfix) with SMTP id A474D37B422 for ; Fri, 25 Aug 2000 20:20:10 -0700 (PDT) Received: (qmail 6557 invoked by uid 1000); 25 Aug 2000 21:26:56 -0000 Date: Sat, 26 Aug 2000 00:26:56 +0300 From: Fred Souza To: security@freebsd.org Subject: nmap OS detection Message-ID: <20000826002656.A6530@torment.secfreak.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Note: \x70\x73\x79\x63\x68 Sender: owner-freebsd-security@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org Hi all, I don't know if it's the right place to ask this, but since it's directly related to security, I think I'm not too wrong. :) I've trying to audit my network using nmap, but there's something wrong. It scans the hosts correctly, but it doesn't detect the remote hosts OSes. I was using the kernel option net.inet.tcp.drop_synfin, and it was causing nmap to not even being able to determine my own localhost OS. After disa- bling that option, it now can tell I'm using a FreeBSD 4.1 box. But it still cannot tell what OSes remote systems run. I've tried to boot the system without any changes through sysctl, and nothing. Tried to disa- ble the firewall (ipf), because I thought it could possibly be any configu- ration mistakes, but no luck. I even tried to detect remote OS from outside my network, against lots of random hosts, and none of those it did so. Any ideas on how to fix that? Thanks in advance, Fred. -- Watch your code, or it'll get you. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-security" in the body of the message