----- Original Message ----- From: "Martin Regner"
| Sudhakar Godithi wrote in | http://www.ethereal.com/lists/ethereal-users/200401/msg00102.html: | > Problem i am getting is Ethereal not recognising the TPKT Header present | > in the IFP, | > | > Its treating TPKT as IFP starting and decoing the TPKT Header with T.38. | | The original T.38 specifications doesn't specify that TPKT is to be used | over TCP, so there is implementations | that are sending T.38 IFP packets directly over TCP as well as | implementations that are sending T.38 IFP | packets over TPKT over TCP. | | I have made a patch to support both T.38IFP/TCP and T38IFP/TPKT/TCP. | | There is one new preference setting tpkt_usage where you can specify if TPKT | header is used. With the default setting (tpkt_usage=Maybe) the dissector | will look on the first four octets and try to determine if TPKT is used or | not. This setting seems to work well with the captures I have tried, | but there might be some scenarios where it will be better to set the value | to 'Always' or 'Never' dependant on if TPKT header is used or not. | | There is also a new preference setting regarding TCP desegmentation. TCP | desegmentation is currently only supported when TPKT header | is used. | You will need to set the preference setting "Allow subdisectors to desegment | TCP streams" for TCP and also the "Desegment all TPKT | messages spanning multiple TCP segments" for TPKT if you want to use this | feature. I don't have any T.38 captures with segmented packets | so I have not been able to test this so much. | | The patch also includes some other changes: | | -Support for T.38 (2002) ASN.1 specification | http://www.itu.int/ITU-T/asn1/database/itu-t/t/t38/2003/T38(2002).html | Note: This ASN.1 specification is incompatible with the Pre-Corigendum T.38 | ASN.1 specification (1998) so you will need to set the preference setting | accordingly. | | -When there are extra octets after the T.38 UDPTL packet you will now see | [Malformed?] in the Info-column. I thought that it | was quite irritating that non-T.38 packets could look like they were | correctly coded T.38 packets. | | -There might be several T.38 IFP packets in a TCP packet for the T.38 | directly over TCP scenario. There is now at least some support for this, but | since | TCP desegmentation is only supported for the TPKT scenario this will not | work if an IFP packet is splitted into several TCP packets. Checked in, along with a comment fix and t38_tpkt_options declared static as no-one else is using it. Regards, Olivier _______________________________________________ Ethereal-dev mailing list [EMAIL PROTECTED] http://www.ethereal.com/mailman/listinfo/ethereal-dev
