Learning by Doing: CISCO Certified Network ... - SCN Research

PAP (Password Authentication Protocol) uses passwords that are sent in clear text during
a two-way handshake process (how secure is that? What is the point?) Basically a
remote user requests a connection by sending a username and password request (one part
of the two-way handshake) the device to be accessed then processes the information and
either accepts or rejects the username and password (the other part of the two-way
handshake). PAP only requests username and passwords once.
CHAP (Challenge Handshaking Authentication Protocol) is similar to PAP except the
username and passwords are encrypted (much better), a three-way handshake is used, and
periodically CHAP re-requests usernames and passwords for authentication. With CHAP
a remote user requests a connection (one part of the three-way handshake), the device to
be accessed then requests a username and password (the second part of the three-way
handshake), the remote user responds with the username and password (still the second
part of the three-way handshake), and the device to be accessed then accepts or rejects the
username and password (the third part).
You will configure and “see” each of these in this lab.
Step-By-Step Instructions:
1. Set up the lab and cable it as shown. Use EIGRP as your routing protocol. Use
the same autonomous number for each network. Use PPP for encapsulation on the
serial lines.
2. Ping from the router prompt of Terminus to Leftist and then to Urvile. It should
work jiffy spiffy-like. Do a trace route between them to verify connectivity.
3. Now that we know everything works lets look at the default state of PPP (without
any user names or passwords):
terminus#debug ppp tasks
Then disconnect the serial line for about 10 seconds and then re-connect it. You
will see the LCP task negotiation and the line come back up. You should see
something like:
terminus# debug ppp tasks
(line is disconnected)
00:52:38: %LINK-3-UPDOWN: Interface Serial0/0, changed state to down
00:52:39: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0,
changed state to down
(line is reconnected)
00:52:49: %LINK-3-UPDOWN: Interface Serial0/0, changed state to up
00:52:49: Se0/0: AAA_PER_USER LCP_UP (0x81483B3C) id 0 (0s.)
queued 1/1/1
00:52:49: Se0/0: AAA_PER_USER LCP_UP (0x81483B3C) id 0 (0s.)
busy/0 started 1/1/1
00:52:49: Se0/0: AAA_PER_USER LCP_UP (0x81483B3C) id 0 (0s.)
busy/0 done in 0 s. 0/0/1
00:52:50: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0,
changed state to up
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