To snif an async connection, you have 2 ways :
The first one is OS dependant.
If you run on win98, you can snif your own dial up adapter and see your own traffic (but not the DLC layer PPP).
The second way will use the old DOS sniffer (Wanbook + Sniffer Network analyzer v5.40) which was supporting with his Y cable the async environment.
Regards. Franck NOLLOT
Sniffer Consultant - Paris (France)
franck_nollot@nai.com