Date: Thu, 1 Aug 1996 15:52:36 +0300 (EET DST) From: Narvi <narvi@haldjas.folklore.ee> To: Webmaster Jim <jspath@mail.bcpl.lib.md.us> Cc: freebsd-ports@freebsd.org Subject: Re: Fwd: Lynx and packet size Message-ID: <Pine.BSF.3.91.960801152707.16254A-100000@haldjas.folklore.ee> In-Reply-To: <9608011143.AA07874@mail>
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On Thu, 1 Aug 1996, Webmaster Jim wrote: > I read this on the lynx-dev list, and thought someone more knowledgable > about FreeBSD could answer the following: > > On Jul 31, 8:52pm, lynx-dev@sig.net wrote: > } From: Klaus Weide <kweide@tezcat.com> > } To: Information Help Desk <info@adn.edu.ph> > } Cc: Lynx Development <lynx-dev@sig.net> > } In-Reply-To: <Pine.LNX.3.91.960801064937.10167A-300000@sili.adn.edu.ph> > } Message-Id: <Pine.SUN.3.94.960731202225.12724C-100000@huitzilo.tezcat.com> > } Reply-To: lynx-dev@sig.net > } On Thu, 1 Aug 1996, Information Help Desk wrote: > } > HI !!! > } > Our server is running the FreeBSD operating system. We ported > } > lynx and have it installed without problems. We tried connecting to > } > popular sites such as www.yahoo.com and www.lycos.com and lynx > } > successfully connects. However, when we tried sites such as > } > www.freebsd.org, ftp.cdrom.com, and www.altavista.digital.com, lynx > } > somehow cannot connect. It stops on the message at the screen's bottom > } > saying, > } > > } > HTTP request sent; waiting for response. > } > > } > And, this goes on forever !!! > } > > } > We tried lynx running in the Linux operating system, and it was > } > able to connect to such sites where lynx in FreeBSD cannot connect to. > } > } I strongly suspect that this has nothing to do with lynx, but with > } the TCP/IP implementation of the operating systems you are using > } and/or your machines' network connections. You should hoave the same > } kind of problems when using other programs from your FreeBSD machine, > } so that connecting to e.g. ftp.cdrom.com with the regular ftp program > } shouldn't work either. > } > } I connected to the five servers you listed from a linux machine and > } watched (with tcpdump) the packets that were received from those > } servers. The three servers that you list as not working have in > } common that they are sending packets longer than the minimum > } MTU of 576 bytes. The two servers that worked for you did not. > } So I think there lies your problem - your networking path cannot > } transmit IP packets greater than 576 bytes, and the FreeBSD OS > } does not properly implement either "Path MTU discovery" or > } "packet fragmentation and reassambly" (or your router does not > } send the required ICMP error messages back to your FreeBSD machine > } when it drops a packet that is too big). I am yet to see anyone find the FreeBSD networking stack deficient. If there is a problem, then it is on the way from your FreeBSD computer to the hosts. BTW. could you connect to these sites with the ordianry ftp program? Perhaps that copy of lynx you ported was broken in some way? Or did you use the official port/package? > } > } If you have a ping command that allows you to specify a size for > } the probe packets (-s option or similar), try it for different > } sizes and see what you get. > } > } I am not familiar with FreeBSD, but probably the easiest solution > } (or workaround) would be to find the proper parameters to use for > } the "ifconfig" command when the machine boots. On Linux, that > } would be something like "ifconfig <...> mtu 576". Or if you > } are using PPP or SLIP to connect to the Internet, use the > } appropriate options there. Of what use could be ifconfig mtu if the problem is on the length of packets the other side sends? Sander > } > } Klaus > }-- End of excerpt from lynx-dev@sig.net > -- > I don't speak (or work) for the Baltimore County Public Library. > They keep telling me, "Shhhhh!" >
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