[lwip-users] PPP bad ack

[Leszek Jakubowski]

Hello,
I've been trying to run lwIP with PPP on an ARM lately and came across a 
problem when trying to connect: kcp_acki: recieved bad Ack!. The error 
message is generated after the check for the Magic Number fails (I'm not 
sure which one).

the debug log shows:
pppMain: unit 0: Connecting
GPRSConnectpppStartCB: unit 0
ppp_set_xaccm[0]: outACCM=0 0 0 0
ppp_send_config[0]: outACCM=FF FF FF FF
ppp_recv_config[0]: inACCM=0 0 0 0
lcp_lowerup: asyncmap=0 0 0 0
LCP: lowerup state 0 -> 2
auth_reset: 0
lcp_addci: L opt=2 0
lcp_addci: L opt=5 34DE8CCF
lcp_addci: opt=7
lcp_addci: opt=8
pppWrite[0]: len=45
fsm_sdata(LCP): Sent code 1,1,20.
LCP: sending Configure-Request, id 1
LCP: open state 2 -> 6
pppInProc[0]: got 75 bytes
pppInput[0]: LCP len=20
fsm_input(LCP):2,1,20
fsm_rconfack(LCP): Rcvd id 1 state=6
lcp_acki: received bad Ack!
LCP: received bad Ack (length 16)
pppInProc[0]: got 46 bytes
pppInput[0]: LCP len=20
fsm_input(LCP):1,1,20
fsm_rconfreq(LCP): Rcvd id 1 state=6
lcp_reqci: rcvd ASYNCMAP=0 MAGICNUMBER (FDAD22) PCOMPRESSION ACCOMPRESSION
lcp_reqci: returning CONFACK.
pppWrite[0]: len=46
fsm_sdata(LCP): Sent code 2,1,20.
pppInProc[0]: got 55 bytes
pppInput[0]: LCP len=8
fsm_input(LCP):9,0,8
pppInput: discarding proto 0x80FD in phase 2
pppInput: discarding proto 0x8021 in phase 2
pppMainWakeup: unit 0 sio_read len=1504 returned 0
LCP: timeout resending Config-Request state=8
lcp_addci: L opt=2 0
lcp_addci: L opt=5 34DE8CCF
lcp_addci: opt=7
lcp_addci: opt=8
pppWrite[0]: len=45
fsm_sdata(LCP): Sent code 1,1,20.
LCP: sending Configure-Request, id 1
pppInProc[0]: got 134 bytes
pppInput: discarding proto 0x80FD in phase 2
pppInput: discarding proto 0x8021 in phase 2
pppInput[0]: LCP len=20
fsm_input(LCP):1,2,20
fsm_rconfreq(LCP): Rcvd id 2 state=8
lcp_reqci: rcvd ASYNCMAP=0 MAGICNUMBER (BF5FA2) PCOMPRESSION ACCOMPRESSION
lcp_reqci: returning CONFACK.
pppWrite[0]: len=45
fsm_sdata(LCP): Sent code 2,2,20.
pppInput[0]: LCP len=20
fsm_input(LCP):2,1,20
fsm_rconfack(LCP): Rcvd id 1 state=8
lcp_acki: received bad Ack!

then it loops more or less

pppd on the other hand recieves a ConfReq with magic number A, sends its 
own ConfReq with magic number B, then replies with ConfAck with magic 
number A and receives ConfAck with magic number B, after that it sends LCP 
EchoReq and tries to send CCP and IPCP ConfReqs with deflated/VJ 
compressed data.after a few seconds LCP ConfReqs go again...

The startup sequence is as follows:
sys_init();
mem_init();
memp_init();
pbuf_init();
tcpip_init(NULL,0);
pppInit();
pppSetAuth(PPPAUTHTYPE_ANY,PPP_LOGIN,PPP_PASS);
currentConf.pppConn = pppOpen(currentConf.serialFd, currentConf.callback, 
NULL);

pppMain has been modified to destroy its own task instead of returning...
Regards

--
Leszek Jakubowski
mailto:address@hidden