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Bug #5544

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Strange HDLC frames in PPP when using mISDN/pppd/capiplugin againt Portmaster3

Added by laforge 27 days ago. Updated 27 days ago.

Status:
New
Priority:
Normal
Assignee:
-
Category:
-
Target version:
-
Start date:
04/23/2022
Due date:
% Done:

0%


Description

I have the following setup:

Server side

  • Portmater3 configured to use L2TP on a certain CalledParty number (03012345051)
  • XL2TPD as LNS on a remote server

Client side

  • Debian unstable with stock debian kernel
  • HFC-S USB-ISDN adapter
  • Stock debian kernel mISDN
  • mISDNuser built from source with its CAPI plugin built
  • stock libcapi20
  • stock debian pppd + capuplugin.so (built from latest isdn-utils)

The phenomenon is quite strange:

  • pppd complains about unsupported PPP protocol 0x7eff:
Apr 23 12:32:05 host3 pppd[12136]: rcvd [proto=0x7eff] 7d 23 c0 21 7d 21 7d 24 7d 20 7d 34 7d 22 7d 26 7d 20 7d 20 7d 20 7d 20 7d 25 7d 26 36 d0 24 3c ...
Apr 23 12:32:05 host3 pppd[12136]: Discarded non-LCP packet when LCP not open
  • wireshark cannot decode those packets "PPP Uknknwon (0x7eff)" (see attached pm3-l2tp-hdlc.pcap)

The connection of course is not established.

I'm right now not sure if it's the client or the server to be blambed here...

In case anyone wants to try, feel free to dial 49-30-1234-3051 from within OCTOI.


Files

pm3-l2tp-hdlc.pcap pm3-l2tp-hdlc.pcap 618 Bytes laforge, 04/23/2022 10:47 AM
zfqveblpuhk.png View zfqveblpuhk.png 13.4 KB manawyrm, 04/23/2022 12:05 PM
Actions #1

Updated by laforge 27 days ago

Actions #2

Updated by laforge 27 days ago

FYI: there is no authentication on that PPP server, but it is currently configure to drop all IP packets. So the max one should be able to get is a proper LCP/IPCP handshake.

Actions #3

Updated by manawyrm 27 days ago

I would suppose your client is at fault :)

Connecting from Windows XP via AVM Fritz!ISDN works perfectly fine.

Actions #4

Updated by manawyrm 27 days ago

Just for reference, this is my known working /etc/xl2tpd/xl2tpd.conf:

[global]
port = 1701
access control = no

[lns default]
ip range = 172.21.118.2-172.21.118.254
local ip = 172.21.118.1
require authentication = yes
name = LinuxDialup
pppoptfile = /etc/ppp/options.xl2tpd
Actions #5

Updated by laforge 27 days ago

  • Subject changed from Strange HDLC frames in L2TP when using Portmaster3 with ISDN + L2TP to Strange HDLC frames in PPP when using mISDN/pppd/capiplugin againt Portmaster3
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