PPP modem differences

[Dan Williams]

On Wed, 2017-03-22 at 13:23 +0000, colin.helliwell at ln-systems.com
wrote:
> I know this might not be an issue with MM, but as there's also a lot
> of
> modem-savvy people here.. :)
> 
> I've got the same system trying to make a ppp connection via MM. I'm
> using
> the same SIM card, and running
>   mmcli -m 0 --simple-connect="apn=mobile.o2.co.uk"
>   pppd nodetach call provider

Quite puzzling; I haven't seen these kinds of requests originating from
the modem before.  But some thoughts:

1) same modem hardware?  If so, same firmware?  If not, I wouldn't be
surprised that different hardware is working differently, though I
haven't seen these kind of challenges from the modem before.

2) Modems do store some state in NVRAM.  Sometimes that can include
things like the default authentication mechanism (CHAP vs. PAP vs.
none).  Perhaps your second device has a different setting for that PDP
context; what does AT+CGDCONT=? say between them?

I assume these are Cinterion devices?  Might be able to use some
Cinterion AT commands to figure out if there are settings differences.

Dan

> On one modem, it works fine. But on the other, it doesn't [though it
> has
> done, with some permutation of versions, in the recent past....]
> The MM logs seem sensible and equivalent, but there are strange
> differences
> in the ppp logs:
> 
> sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x90170814> <pcomp>
> <accomp>]
> rcvd [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x6b7e4a17> <pcomp>
> <accomp>]
> sent [LCP ConfAck id=0x1 <asyncmap 0x0> <magic 0x6b7e4a17> <pcomp>
> <accomp>]
> rcvd [LCP ConfAck id=0x1 <asyncmap 0x0> <magic 0x90170814> <pcomp>
> <accomp>]
> kernel does not support PPP filtering
> sent [CCP ConfReq id=0x1 <deflate 15> <deflate(old#) 15> <bsd v1 15>]
> sent [IPCP ConfReq id=0x1 <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2
> 0.0.0.0>]
> rcvd [LCP ProtRej id=0x2 80 fd 01 01 00 0f 1a 04 78 00 18 04 78 00
> 15]
> Protocol-Reject for 'Compression Control Protocol' (0x80fd) received
> sent [IPCP ConfReq id=0x1 <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2
> 0.0.0.0>]
> rcvd [IPCP ConfReq id=0x1]
> sent [IPCP ConfNak id=0x1 <addr 0.0.0.0>]
> rcvd [IPCP ConfNak id=0x1 <addr 10.232.128.88> <ms-dns1 10.203.128.1>
> <ms-dns2 10.203.128.1>]
> sent [IPCP ConfReq id=0x2 <addr 10.232.128.88> <ms-dns1 10.203.128.1>
> <ms-dns2 10.203.128.1>]
> rcvd [IPCP ConfReq id=0x2 <addr 10.232.128.88>]
> sent [IPCP ConfAck id=0x2 <addr 10.232.128.88>]
> rcvd [IPCP ConfAck id=0x2 <addr 10.232.128.88> <ms-dns1 10.203.128.1>
> <ms-dns2 10.203.128.1>]
> not replacing default route to eth0 [192.168.100.1]
> local  IP address 10.232.128.88
> remote IP address 10.232.128.88
> primary   DNS address 10.203.128.1
> secondary DNS address 10.203.128.1
> 
> sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0xf16ed179> <pcomp>
> <accomp>]
> rcvd [LCP ConfNak id=0x1 <asyncmap 0xa0000>]
> sent [LCP ConfReq id=0x2 <asyncmap 0xa0000> <magic 0xf16ed179>
> <pcomp>
> <accomp>]
> rcvd [LCP ConfAck id=0x2 <asyncmap 0xa0000> <magic 0xf16ed179>
> <pcomp>
> <accomp>]
> rcvd [LCP ConfReq id=0x3 <asyncmap 0xa0000> <pcomp> <accomp> <magic
> 0x549d043f> <auth chap MD5>]
> No auth is possible
> sent [LCP ConfRej id=0x3 <auth chap MD5>]
> rcvd [LCP ConfReq id=0x5 <asyncmap 0xa0000> <pcomp> <accomp> <magic
> 0x549d043f> <auth pap>]
> No auth is possible
> sent [LCP ConfRej id=0x5 <auth pap>]
> rcvd [LCP ConfReq id=0x7 <asyncmap 0xa0000> <pcomp> <accomp> <magic
> 0x549d043f>]
> sent [LCP ConfAck id=0x7 <asyncmap 0xa0000> <pcomp> <accomp> <magic
> 0x549d043f>]
> kernel does not support PPP filtering
> sent [CCP ConfReq id=0x1 <deflate 15> <deflate(old#) 15> <bsd v1 15>]
> sent [IPCP ConfReq id=0x1 <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2
> 0.0.0.0>]
> rcvd [LCP ProtRej id=0x8 80 fd 01 01 00 0f 1a 04]
> Protocol-Reject for 'Compression Control Protocol' (0x80fd) received
> rcvd [LCP TermReq id=0x9]
> LCP terminated by peer
> sent [LCP TermAck id=0x9]
> rcvd [LCP TermReq id=0x9]
> sent [LCP TermAck id=0x9]
> Connection terminated.
> Modem hangup
> 
> I'm puzzled why, with the same software and SIM/provider/APN, the
> non-working modem is 
> a) receiving a "LCP ConfNak id=0x1 <asyncmap 0xa0000>]",  when the
> working
> one gets an Ack to the same Req
> b) receiving a "LCP ConfReq id=0x3 <asyncmap 0xa0000> <pcomp>
> <accomp>
> <magic 0x549d043f> <auth chap MD5>" - or indeed why it's *receiving*
> a
> ConfReq at all.
> 
> Are there characteristics in the modem which could alter how MM
> behaves? (Or
> what the local and remote ppp's are sending/negotiating)
> Any expertise welcome!
> 
> 
> 
> 
> 
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