Date: Tue, 16 Jun 1998 08:10:40 +0200 From: Christoph Kukulies <kuku@gilberto.physik.RWTH-Aachen.DE> To: Doug White <dwhite@resnet.uoregon.edu> Cc: Christoph Kukulies <kuku@gilberto.physik.RWTH-Aachen.DE>, freebsd-questions@freefall.cdrom.com Subject: Re: using tcpdump effectively Message-ID: <19980616081040.53544@gil.physik.rwth-aachen.de> In-Reply-To: <Pine.BSF.3.96.980615202757.2150D-100000@gdi.uoregon.edu>; from Doug White on Mon, Jun 15, 1998 at 08:29:47PM -0700 References: <199806151447.QAA29137@gilberto.physik.RWTH-Aachen.DE> <Pine.BSF.3.96.980615202757.2150D-100000@gdi.uoregon.edu>
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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' > > 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
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