From owner-freebsd-questions Tue Jun 16 01:33:09 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id BAA23785 for freebsd-questions-outgoing; Tue, 16 Jun 1998 01:33:09 -0700 (PDT) (envelope-from owner-freebsd-questions@FreeBSD.ORG) Received: from freefall.freebsd.org (freefall.FreeBSD.ORG [204.216.27.21]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id BAA23764 for ; Tue, 16 Jun 1998 01:32:58 -0700 (PDT) (envelope-from malte@webmore.com) Received: from cyclone.degnet.baynet.de (www.degnet.baynet.de [194.95.214.129]) by freefall.freebsd.org (8.8.8/8.8.5) with SMTP id BAA24442 for ; Tue, 16 Jun 1998 01:32:03 -0700 (PDT) Received: from neuron.webmore.com (unverified [194.95.214.162]) by cyclone.degnet.baynet.de (EMWAC SMTPRS 0.83) with SMTP id ; Tue, 16 Jun 1998 10:34:36 +0200 Received: (from malte@webmore.com) by neuron.webmore.com (8.8.8/8.8.8) id KAA00858; Tue, 16 Jun 1998 10:30:02 +0200 (CEST) Message-ID: X-Mailer: XFMail 1.2 [p0] on FreeBSD X-Priority: 3 (Normal) Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8bit MIME-Version: 1.0 In-Reply-To: <19980616081040.53544@gil.physik.rwth-aachen.de> Date: Tue, 16 Jun 1998 10:30:02 +0200 (CEST) Reply-To: malte@webmore.com From: Malte Lance To: Christoph Kukulies Subject: Re: using tcpdump effectively Cc: freebsd-questions@freefall.cdrom.com, Doug White Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On 16-Jun-98 Christoph Kukulies wrote: > On Mon, Jun 15, 1998 at 08:29:47PM -0700, Doug White wrote: >> On Mon, 15 Jun 1998, Christoph Kukulies wrote: >> >> > >> > To trace down why some network based X11 sessions are spuriously failing >> > I' trying to use tcpdump. >> > >> > What sporadically happens is that a X session to our Mentor Design >> > Architect >> > running on HP is ceased and the connection breaks (we login via rlogin >> > and start the X client with DISPLAY set to the FreeBSD machine.) >> > >> > When the connection breaks we see something like 'no route to host' Who is loosing the route ? Displaying-machine or the machine running the app ? What about running a continious ping from the displaying-machine to the HP-machine to keep the route up. If this helps, there is really a routing- problem. How are the routes build up ? Routing daemon or static routes ? Malte. >> >> Most likely the client is loosing the network connection to the host, >> either by damage to the routing tables on the client or on an intermediate >> network device. Run a traceroute to the HP box when MDA crashes and see if >> it fails anywhere. > > As stated in a previous reply, it happens even on the local ethernet. > So there is no hop involved and I don't see a reason > why there should be a 'route lost' or no 'route to host'. > >> >> > Could that be caused by denial of service attacks? What exactly is a >> > denial >> > of service attack? >> >> A denial of service attack (DoS) attempts to keep a machine from being >> servicable by overwhelming it with requests or by disabling a server, >> rending it useless. > > OK, this doesn't seem to be the case here. > >> >> Doug White | University of Oregon >> Internet: dwhite@resnet.uoregon.edu | Residence Networking Assistant >> http://gladstone.uoregon.edu/~dwhite | Computer Science Major >> NOTICE: Make sure your mailer replies to dwhite@resnet or I won't get it! > > -- > --Chris Christoph P. U. Kukulies kuku@gil.physik.rwth-aachen.de > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-questions" in the body of the message ---------------------------------- E-Mail: Malte Lance Date: 16-Jun-98 Time: 10:16:12 ---------------------------------- To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message