Enterasys Networks X-Pedition XSR CLI - Manual (Page 356)

PPP Commands
8-86 Configuring the Point-to-Point Protocol
XSR(config)#interface serial 1/0
XSR(config-if)#encapsulation ppp
XSR(config-if)#no shutdown
The following example selects channel group 12 of the T1/E1 port1 on the second NIM card so that
later configurations will apply to this serial port:
XSR(config)#interface serial 2/1:12
XSR(config-ifXSR(config-if)#no shutdown
ppp authentication
This command specifies the type and order in which CHAP, MS‐CHAP or PAP protocols are
requested on the interface. Once CHAP, PAP authentication or both have been enabled, the XSR
requires the remote device to prove its identity before allowing data traffic to flow.
PAP authentication requires the remote device to send a name and password to be checked
against a matching entry in the local username database.
CHAP authentication sends a challenge to the remote device. The remote device must encrypt the
challenge value with a shared secret and return the encrypted value and its name to the XSR in a
response message. The XSR uses the remote deviceʹs name to look up the appropriate secret in the
local username database. It uses the looked‐up secret to encrypt the original challenge and verify
that encrypted values match.
MS‐CHAP is closely derived from the PPP CHAP with the exception that it uses MD4 as the
hashing algorithm.
You may enable PAP or CHAP, MS‐CHAP or all of them, in either order. If both methods are
enabled, then the first method specified will be requested during link negotiation. If the peer
suggests using the second method or simply refuses the first, then the second method is tried.
Some remote devices support CHAP only and some PAP only. The order in which you specify the
methods will be based on your concerns about the remote deviceʹs ability to correctly negotiate the
appropriate method as well as your concern about data line security. PAP usernames and
passwords are sent as clear‐text strings and can be intercepted and reused. CHAP has eliminated
most of the known security holes.
Enabling or disabling PPP authentication does not affect the XSRʹs willingness to authenticate
itself to the remote device.
Syntax
ppp authentication {any mix of pap chap ms-chap}
Possible parameter combinations include:
Note: If you specify CHAP authentication on one side of a connection, you should set CHAP on the
other side as well.
chap Enables CHAP on a serial interface.
pap Enables PAP on a serial interface.
ms-chap Enables MS‐CHAP on a serial interface.
chap pap Preference of CHAP authentication before PAP.
pap chap Preference of PAP authentication before CHAP.