ppp_codes.txt

shutdown reasons:

1	failed to negotiate a VITAL PPP option
2	no more attempts to restart
3	received proto reject
4	received code reject
5	inactive timer fired
6	admin shutdown
7	received terminate request
8	auth backend failed
9	auth: incorrect login/passwd
10	no response from peer
11	disconnected by CoA
12	PPP FSM failed to converge
14	no resources left
13	unknown or other reason
15	the peer hasn't replied to keepalive probes
16	ppp username is already being used

ppp auth results:

0	undefined
1	success
2	denied
3	auth backend failed
4	peer failed