Date: Thu, 26 Oct 2000 20:11:26 -0400 From: "Gary T. Corcoran" <gcorcoran@lucent.com> To: Aaron Hill <hillaa@hotmail.com> Cc: julian@elischer.org, freebsd-questions@FreeBSD.ORG, freebsd-net@FreeBSD.ORG Subject: Re: More on PPPoE & ADSL (Telstra Bigpond) Message-ID: <39F8C82E.2C61CF55@lucent.com> References: <F50iFEW6sStwNeKjUbE00001146@hotmail.com>
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Aaron Hill wrote: ... > I agree, I think it's tcpdump trying, incorrectly, to interpret the tag > contents. In case you'd like to see what the Host-Uniq tags actually > contained here's some hex of the Windows PADI frame... > > 0:10:5a:0:d3:de Broadcast 8863 60: PPPoE PADI [Host-Uniq UTF8] [Service-Name > "bigpond"] > 0x0000 1109 0000 0015 0103 0006 0010 5a00 d3de ............Z... > 0x0010 0101 0007 6269 6770 6f6e 6400 0000 0000 ....bigpond..... > 0x0020 0000 0000 0000 0000 0000 0000 0000 .............. > > ... and the FreeBSD PADI frame... > > 0:e0:29:73:81:dd Broadcast 8863 60: PPPoE PADI [Service-Name "bigpond"] > [Host-Uniq UTF8] > 0x0000 1109 0000 0013 0101 0007 6269 6770 6f6e ..........bigpon > 0x0010 6401 0300 0480 7067 c300 0000 0000 0000 d.....pg........ > 0x0020 0000 0000 0000 0000 0000 0000 0000 .............. This would be a bug in the head-end and not the FreeBSD implementation, but what if... The Windows PADI frame accidentally has the Service-Name terminated with a NULL. It is NOT required by the standard, but what if the head-end is scanning for the Service-Name string that way? The way the FreeBSD frame is constructed, with the Host-Uniq tag immediately after the Service-Name, it is not (pseudo) NULL-terminated, and never will be for this format. Just to make it clear, it is not _supposed_ to be Null-terminated, but if the head-end has this bug, both the Windows and Linux implementations would happen to satisfy it. Just a thought... Gary To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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