At PPP dial failure, how to debug in Linux environment?

First, PPP can release debug & kedebug debug Options in the options file

Second, Linux kernel journaling can be viewed through cat/var/log/syslog.1

The following are the relevant steps for Linux

2. Cd/etc/ppp
   

4. Ls

6. VI Options

8.   Change #debug to debug

   # Increase debugging level (same as-d) .  If This option is given, PPPD
   # would log the contents of all control packets sent or received in a
   # readable form.  the packets is logged through syslog with facility
   # Daemon and level Debug. This information can is directed to a file by
   # setting up/etc/syslog.conf appropriately (see syslog.conf (5)) .  ( If
   # PPPD is compiled with extra debugging enabled, it'll log messages
   # using facility Local2 instead of daemon).
   #debug

   Debug
   

10. Change #kdebug n to kdebug 1

    # Enable Debugging code in the Kernel-level PPP driver. The argument n
    # is a number which are the sum of the following values:1 to enable
    # General Debug messages, 2 to request that the contents of received
    # packets is printed, and 4 to request that the contents of transmitted
    # packets be printed.
    #kdebug N

    Kdebug
    

12. Device dialing

14. Cat/var/log/syslog.1 > Ppp_debug_history.log

Summarize:

The problem encountered this time is the MRU size mismatch problem, the terminal's MRU setting is the default of 576 (556+20),

However, the server configuration of the MRU size is 1500, the result terminal initiates the first dial, MRU mismatch, resulting in dial failure.

This article is from the "mountain Ask the Boy" blog, please be sure to keep this source http://linpeng.blog.51cto.com/9779987/1676063

At PPP dial failure, how to debug in Linux environment?