Indeed, ppp_async doesn't handle that case correctly.
RFC 1662 says:
The Control field is a single octet, which contains the binary
sequence 00000011 (hexadecimal 0x03), the Unnumbered Information
(UI) command with the Poll/Final (P/F) bit set to zero.
The use of other Control field values may be defined at a later
time, or by prior agreement. Frames with unrecognized Control
field values SHOULD be silently discarded.
In what situation were we getting the frames that cause the problem?
I didn't see the patch (the message that this is a reply to is the
first one that I have seen in this thread), so I can't comment on it.
Paul.
-