Description of problem:

pppd fails on filter with 'outbound/inbound' qualifiers

| # pppd active-filter 'outbound'
| pppd: error in active-filter expression: inbound/outbound not
supported on linktype 0

Such kind of filter is required e.g. for idle-detection. They should
work because 'pppd' accepts the same expression like 'tcpdump':

| # tcpdump -i ppp0 'outbound' -nn
| tcpdump: verbose output suppressed, use -v or -vv for full protocol
decode


I suspect some changed behavior in the underlying libpcap: the
qualifiers are working on special devices only. On tcpdump it is given
by '-i ppp0', but with pppd, a default type will be assumed which does
not support it. But this is just a wild guess without looking at the code.


Version-Release number of selected component (if applicable):

ppp-2.4.2-3.FC2.1
libcap-1.10-18.1


How reproducible:

100%