INSYS Pocket ISDN
Functions
51
10.14
Details about Multilink PPP (only INSYS Pocket ISDN
Internet)
The following authentication protocols (AP) are supported by the INSYS Pocket
ISDN Internet with Multilink PPP (ML PPP) at the moment:
Password Authentication Protocol (PAP)
Challenge Handshake Authentication Protocol (CHAP) with variants
MD5 according RFC 1321
Microsoft CHAP according RFC 2433
PAP exchanges the password in clear text format in the B channel, while CHAP
encrypts the password according to the algorithms as described in above
mentioned RFCs. For CHAP, the password must be stored in the INSYS Pocket
ISDN Internet in addition to the settings in Dial-Up Networking under Windows 95.
This is not necessary under Windows 98/ME/2000/XP.
The following basic rules are valid if the INSYS Pocket ISDN Internet is configured
for ML-PPP:
If the remote side (in the connection control protocol LCP ConfigRequest)
requests an AP, which can be handled by the INSYS Pocket ISDN Internet,
the request will be forwarded to the local side.
If the remote side requests an AP, which cannot be handled by the INSYS
Pocket ISDN Internet, the INSYS Pocket ISDN Internet suggests the safest
protocol depending on the preconditions:
- PAP, if no password "chappwd" is stored locally
- CHAP/MS-CHAP MD5, if a password "chappwd" is stored locally
This step can be repeated with a certain number of attempts. Then, the
INSYS Pocket ISDN Internet falls back to single link operation until the next
connection attempt.
As soon as the local side (with an LCP ConfigNak) refuses an AP, which
has been suggested by the INSYS Pocket ISDN Internet alternatively (refer
to previous rules), the INSYS Pocket ISDN Internet falls back to single link
operation until the next connection attempt. Local and remote side
negotiate any AP.
The negotiated AP is cehecked at the end of the connection setup
procedure and, if supported, also used for the second connection. If the
last AP is not supported, the second connection will not be established.
The INSYS Pocket ISDN Internet falls back to single link operation until the
next connection attempt.
Please note that some hosts are very stringent. If, for example, PAP is suggested
by the INSYS Pocket ISDN because no "chappwd" password is present, the
connection is simply terminated without the chance to negotiate any other
protocol. In these cases, the INSYS Pocket ISDN Internet should be configured for
single link PPP operation or the "chappwd" password should be stored in the
INSYS Pocket ISDN Internet.
