Date: Fri, 5 Oct 2001 16:31:54 +0100 (BST) From: Alex Dyas <adyas@twowaytv.com> To: <questions@freebsd.org> Subject: telnet problem Message-ID: <20011005162723.V39489-100000@r2d2.twowaytv.co.uk>
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hi, the problem - telnet sessions from FreeBSD 4.2R machine across an (internal) firewall to a solaris machine suffer from long delays if left un-attended for more than around 10 seconds. in other words, i telnet, do some stuff, all is fine. leave fbsd machine alone for ~10+ seconds, try to start typing again and the session appears to be locked up for about 5+ seconds before it responds again. ssh seems to suffer from the same problem. a tcpdump of the session shows that a telnet ack from the solaris machine seems to be the trigger : 16:05:14.251640 fbsd_machine.4360 > solaris_machine.telnet: . ack 4 win 17520 (DF) [tos 0x10] 16:05:14.351688 fbsd_machine.4360 > solaris_machine.telnet: P 3:5(2) ack 4 win 17520 (DF) [tos 0x10] 16:05:14.352186 solaris_machine.telnet > fbsd_machine.4360: P 4:6(2) ack 5 win 8760 (DF) 16:05:14.456755 fbsd_machine.4360 > solaris_machine.telnet: . ack 6 win 17520 (DF) [tos 0x10] 16:05:14.457095 solaris_machine.telnet > fbsd_machine.4360: P 6:74(68) ack 5 win 8760 (DF) 16:05:14.551646 fbsd_machine.4360 > solaris_machine.telnet: . ack 74 win 17520 (DF) [tos 0x10] 16:05:30.370151 solaris_machine.telnet > fbsd_machine.4360: . ack 5 win 0 <- trigger 16:05:30.370203 fbsd_machine.4360 > solaris_machine.telnet: . ack 74 win 17520 (DF) [tos 0x10] 16:05:41.811973 fbsd_machine.4360 > solaris_machine.telnet: . 5:6(1) ack 74 win 17520 (DF) [tos 0x10] 16:05:41.853928 solaris_machine.telnet > fbsd_machine.4360: . ack 6 win 8760 (DF) 16:05:41.853977 fbsd_machine.4360 > solaris_machine.telnet: P 6:7(1) ack 74 win 17520 (DF) [tos 0x10] windows and linux machines on the same subnet as the fbsd machine do not have the same problem. telnetting from the solaris machine through the firewall to the bsd machine is not a problem. telnetting from the bsd machine to a solaris machine on the same subnet is not a problem, in fact using a local solaris machine as a 'spring-board' to machines on the other side of the firewall is how i've kept sane so far. the problem seems to be specific to FreeBSD. i haven't been able to try fbsd->firewall->fbsd yet, but my suspicion is that the problem will still occur. looking for a reason for this i see that similar problems have been linked to reverse DNS issues. i do not believe this is the same thing as, a) i've tried adding DNS and host entries in all the appropriate places with no luck, and b) the delays are experienced AFTER the initial connection is made, not during as would be expected. one obvious problem is firewall misconfiguration which i suspected for a long time. if this is the case, why is it that only fbsd is affected, windows and linux are fine? if it is the firewall, what sort of configuration would cause these problems but still allow the telent through in the first place? although this isn't a show stopper, it's been driving me nuts over the last few months. i'd really like to find out why it's happening, and then how to fix it. thanks, alex.. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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