Date: Tue, 16 Jun 1998 10:30:02 +0200 (CEST) From: Malte Lance <malte@webmore.com> To: Christoph Kukulies <kuku@gilberto.physik.RWTH-Aachen.DE> Cc: freebsd-questions@freefall.cdrom.com, Doug White <dwhite@resnet.uoregon.edu> Subject: Re: using tcpdump effectively Message-ID: <XFMail.980616103002.malte@webmore.com> In-Reply-To: <19980616081040.53544@gil.physik.rwth-aachen.de>
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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 <malte@webmore.com> 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
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