Dial-up Networking (PPP) V

Summary:

• Generating Error-Logs
• Modem doesn't react at all
• Modem does react, but doesn't dial
• Modem dials every second time only
• Modem does react and dial, but it drops the connection immediately
• Modem does react, dials but drops connection after 20 seconds
• Connection establishes, holds, but you can't get anywhere

Questions, suggestions, corrections? Visit the Board?1.1

1 Generating Error-Logs

'pppd' logs messages in '/var/log/messages'. This is the first place to have a look at if something doesn't work (e.g.

less /var/log/messages

• Make a backup of '/etc/syslog.conf' (e.g.

  cp /etc/syslog.conf /etc/syslog.conf.orig

  )
• Add these lines to /etc/syslog.conf:

local2.* /var/log/ppp daemon.* /var/log/ppp

• Run

touch /var/log/ppp

• Start 'pppd' with the 'debug' option, like

  /usr/sbin/pppd debug call {name}

  This will log every message sent and received by 'pppd' to '/var/log/ppp'.
• If you've got everything up and running, you might want to revert these changes by copying back '/etc/syslog.conf.orig'.

Modem doesn't react at all

• You've specified a wrong serial port. Check your settings in the 'peers' file.
• Check your cable connections.

Modem does react, but doesn't dial

Have a look at '/var/log/messages'. Most likely you will see this message:

Connect script failed

This may have various reasons:

• Bad chat-script. Check filename of chat-script, check modem init-string, look for typos. Increase time-out or try the chat-script provided by the ppp.rpm ('/usr/doc/ppp-{version}/scripts/ppp-on-dialer').
• Bad telephone line, flaky modem. Remove the appropriate ABORT options from your chat-script ("NO ANSWER", "NO DIALTONE") one by one. At some point pppd will not time out. This is where the error lies.

Modem dials every second time only

Your modem is set to 'Abort connection if DTR ? OFF' ('&D2'). Add

&D1

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Modem does react and dial, but it drops the connection immediately

• Check telephone-number.
• Try again. Maybe your ISP's server was just busy at that moment.
• Check your scripts for typos1.1
• Make sure you have no superfluous entries in '/etc/ppp/options'.

Modem does react, dials but drops connection after 20 seconds

'/var/log/messages' (or '/var/log/ppp') reads:

LCP: timeout sending Config-Requests

• Check the 'options'-file. Add these options

• asyncmap 0xa0000

• novj

• Check '/var/log/ppp' for entries like

  <auth pap>

  or

  <auth chap>

  . Do you use the right 'secrets' file? Enter your account name and passwords into both files and try again.
  If you see messages like "Unknown digest type" or "Unknown CHAP code", your provider uses non-standard authentification protocols. Demand an alternative login-procedure and if they fail to, get a new provider.

Connection establishes, holds, but you can't get anywhere

• Being offline, run

  /sbin/route -n

  as root. There shouldn't be any entry starting with '0.0.0.0'. Such an entry means that there already is a default route on your system. In this case, run

  /sbin/route del default

  . Try to find out what sets this default route.
  The 'Linuxconf' version distributed with LM 7 seems to insist on setting a default route, if you configure a local network and a dial-up connection with it. Check the file '/etc/sysconfig/network' and remove any lines which start with GATEWAY or GATEWAYDEV.
• Check the entries in /etc/resolv.conf for correctness.
• Add one or more of these options to '/etc/ppp/options':
  

  defaultroute

  ,

  noipdefault

  ,

  noccp

  ,

  nobsdcomp

  ,

  novj

  ,

  novjcomp

  ,

  noaccomp

  ,

  nopcomp

  .
  This varies from ISP to ISP, so try until you find a combination which works ;-).

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Related Resources:

Linux PPP FAQ
PPP HOWTO, 22
Modem HOWTO, 15

Modified: July 21, 2000
Author: Tom Berger

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