Date: Thu, 22 Jun 2000 21:00:57 +0800 From: Victor Tsang <victor.tsang@ieee.org> To: Dave Stevens <dave@consource.com>, <questions@freebsd.org> Subject: Re: Mac's, FreeBSD, PPPoe and DSL Message-ID: <B5782F09.FC7%victor.tsang@ieee.org> In-Reply-To: <002c01bfdbaa$df461aa0$9c00a8c0@fusion4.com>
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NAT don't work because the mtu size (a kind of date packet size) for PPPoE must be 1492 (or someting similar) and ethernet's mtu size is by default 1500. For NATing, nat will request the "client" to change the mtu size from 1500 to 1492 so as to match the PPPoE protocol. However, Mac and windows deny to change the mtu size and therefore your local LAN clients will suffer packet loss. If your LAN machines are all windows boxes, go search my previous messages that there was a reply telling me how to force windows to change mtu size and your problem will be solved. For Mac, I have no idea. For Darwin, I have to make some changes to the kernel to support "ifconfig en0 mtu 1492". I am working on this, but since I have little free time to do it, the progress is near zero. :( What I am using is Windows 2000 + a free PPPoE dialup driver. If the client deny to tune down the mtu size, win2K nat will break the incoming packet into 2 and also resemble the incoming packets to mtu=1500 to foo the clients (so the speed is slower! but slower is better than none.) on 6/22/00 2:02 AM, Dave Stevens at dave@consource.com wrote: I saw your post to the mailling lists back in the end of May and I was wondering if you ever got this problem resolved? I'm having the same exact problem, and it's happening with both Windows and Mac clients. Any help would be greatly appreciated. Dave > From Mailing list Post: I am new to FreeBSD and it is my first time to install FreeBSD. I installed FreeBSD 4.0 and am going to configure PPPoE and NAT. I followed the instructions found in FreeBSD.org web site and man pages and easily get PPPoE work. However, NAT don't work and its behavior is strange. My environment is one FreeBSD running as gateway, connecting my LAN and ISP using PPPoE and there is a Macintosh running Darwin in the LAN for my testing purpose. Either I don't enable NAT in rc.conf, or set ppp_nat="YES" , the behaviors are the same: In Macintosh, when I telnet to outside world, I can see the login screen and login prompt. Once I key in the user name and password, there is nothing to show on screen and eventually the telnet timeout and disconnected. Similarly in ftp: I can login ftp server but get no response after playing a very short while. ftp> user anonymous 123@123 ftp> dir (show something) ftp> cd pub (OK.) ftp> dir (no response! I tested for about 4-5 sites. All are "die" in dir the /pub directory.) I suspect two possibilities: 1. only the first packet (mtu or mur?) are transmitted successful but the subsequent packets are failed. 2. Something wrong in telnet and ftp packet translation. However, I have no clue on how to proceed futher. The /var/log/alias.log shows nothing helpful. -- Victor Tsang victor.tsang@ieee.org write to you at home using Outlook Express Macintosh To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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