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6. Troubleshooting

So you've read through this document, the Modem-HOWTO, and the PPP Howto, are pretty sure that your modem matches one of the drivers available, but it still doesn't work? There are a number of points in the process at which something could break down. Marvin Stodolsky writes:

Linux generally maintains records of networking connections which are very useful in troubleshooting problems. Their particular filenames vary with both the Linux distribution and Dial-in software. For both your own trouble shooting and queries for help to a list, it will be useful if you accumulate the information requested below. As Root, start a script record named say, Modem test. After this script is terminated with "exit," copy it out of your Linux partition for transmission to the List which may aid you. Change to the directory in which the modem install scripts are located. Below, # are explanatory comments.

# start the recording,
script ModemTest.txt 
# type in as much info on your Modem card as you have
echo winmodem name, manufacturer, designation, and chip if possible
# this gives your current kernel version
uname -r
# this gives information on your serial ports
setserial -agv /dev/ttyS*
# this information on your interrupts (irq)
cat /proc/interrupts
# show the contents of your module installation script (insert script name):
cat ScriptName
# Check if your script is executable:
ls -l ScriptName
# a response is OK if it has "x" such as below:
# -rwxrw-rw-  1 root     root  654 Jan  6  2000 ltinst
# otherwise make it executable with:
chmod o+x ScriptName
# verify with
ls -l ScriptName
# if ScriptName has not been successfully run before under this kernel
# run it with:
./ScriptName
# what is the symbolic link /dev/modem set to:
ls -l /dev/modem
# What is the DeviceName specified in the ScriptName (/dev/ttyS14 or ...?)
echo DeviceName
# what is your modem driver name? Something like DriverName.o
# with the ".o" indicating it is a compiled binary
echo This is my DriverName.o
# if should have been inserted in the Modules Path
# Try to display it there with:
find /lib/modules | grep DriverName
# Is DriverName among the modules installed in the running kernel?
lsmod
# if not try a simple insertion:
insmod ./DriverName.o
# or if it was in the Modules Path, the following will suffice:
insmod DriverName
# check for insertion:
lsmod
# if not inserted, try forcing:
insmod -f ./DriverName
# list your inserted modules again.
lsmod
# If DriverName is NOT listed, 
# their is an incompatibility between modem hardware, driver and kernel.
# Further effort will be of No use.
# If DriverName is listed, let's do a bit more information.
# You may first wish to rerun the configuration utility 
# used to setup dial-in connections for your Linux installation.
# Remember to edit your PassWord from this record later.
# You will probably be queried for the following information 
# which you should have ready:
#Port to be used (/dev/modem or /dev/ttySn),Dial-inNumber, UserName, PassWord. 
# Run your configuration utility.
YourSetUpConf
# To stop recording 
exit

If dialin was not successfull, append to this a record from your log file. As an example, a section of a /var/log/syslog from a Debian Linux system is below.

Aug 21 08:35:41 koala kernel: CSLIP: code copyright 1989 Regents of the University of California
Aug 21 08:35:41 koala kernel: PPP: version 2.3.7 (demand dialling)
Aug 21 08:35:41 koala kernel: PPP line discipline registered.
Aug 21 08:35:42 koala kernel: registered device ppp0
Aug 21 08:35:42 koala pppd[1539]: pppd 2.3.11 started by root, uid 0
Aug 21 08:35:43 koala chat[1545]: abort on (BUSY)
Aug 21 08:35:43 koala chat[1545]: abort on (NO CARRIER)
Aug 21 08:35:43 koala chat[1545]: abort on (VOICE)
Aug 21 08:35:43 koala chat[1545]: abort on (NO DIALTONE)
Aug 21 08:35:43 koala chat[1545]: abort on (NO DIAL TONE)
Aug 21 08:35:43 koala chat[1545]: abort on (NO ANSWER)
Aug 21 08:35:43 koala chat[1545]: send (ATZ^M)
Aug 21 08:35:43 koala chat[1545]: expect (OK)
Aug 21 08:35:43 koala chat[1545]: ATZ^M^M
Aug 21 08:35:43 koala chat[1545]: OK
Aug 21 08:35:43 koala chat[1545]:  -- got it 
Aug 21 08:35:43 koala chat[1545]: send (ATQ0V1E1S0=0&C1&D2S11=55+FCLASS=0^M)
Aug 21 08:35:44 koala chat[1545]: expect (OK)
Aug 21 08:35:44 koala chat[1545]: ^M
Aug 21 08:35:44 koala chat[1545]: ATQ0V1E1S0=0&C1&D2S11=55+FCLASS=0^M^M
Aug 21 08:35:44 koala chat[1545]: OK
Aug 21 08:35:44 koala chat[1545]:  -- got it 
Aug 21 08:35:44 koala chat[1545]: send (ATDT17574238738^M)
Aug 21 08:35:44 koala chat[1545]: expect (CONNECT)
Aug 21 08:35:44 koala chat[1545]: ^M
Aug 21 08:36:16 koala chat[1545]: ATDT17574238738^M^M
Aug 21 08:36:16 koala chat[1545]: CONNECT
Aug 21 08:36:16 koala chat[1545]:  -- got it 
Aug 21 08:36:16 koala chat[1545]: send (\d)
Aug 21 08:36:17 koala pppd[1539]: Serial connection established.
Aug 21 08:36:17 koala pppd[1539]: Using interface ppp0
Aug 21 08:36:17 koala pppd[1539]: Connect: ppp0 <--> /dev/ttyS14
Aug 21 08:36:18 koala pppd[1539]: sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x64acd5df> <pcomp> <accomp>]
Aug 21 08:36:18 koala pppd[1539]: rcvd [LCP ConfReq id=0x1 < 00 04 00 00> <mru 1524> <asyncmap 0xa0000> <auth pap> <pcomp> <accomp> < 11 04 05 f4> < 13 09 03 00 c0 7b 7d 08
8c>]
Aug 21 08:36:18 koala pppd[1539]: sent [LCP ConfRej id=0x1 < 00 04 00 00> < 11 04 05 f4> < 13 09 03 00 c0 7b 7d 08 8c>]
Aug 21 08:36:18 koala pppd[1539]: rcvd [LCP ConfAck id=0x1 <asyncmap 0x0> <magic 0x64acd5df> <pcomp> <accomp>]
Aug 21 08:36:18 koala pppd[1539]: rcvd [LCP ConfReq id=0x2 <mru 1524> <asyncmap 0xa0000> <auth pap> <pcomp> <accomp>]
Aug 21 08:36:18 koala pppd[1539]: sent [LCP ConfAck id=0x2 <mru 1524> <asyncmap 0xa0000> <auth pap> <pcomp> <accomp>]
Aug 21 08:36:18 koala pppd[1539]: sent [LCP EchoReq id=0x0 magic=0x64acd5df]
Aug 21 08:36:18 koala pppd[1539]: sent [PAP AuthReq id=0x1 user="stodolsk" password=<hidden>]
Aug 21 08:36:19 koala pppd[1539]: rcvd [LCP EchoRep id=0x0 magic=0x0]
Aug 21 08:36:19 koala pppd[1539]: rcvd [PAP AuthAck id=0x1 ""]
Aug 21 08:36:19 koala pppd[1539]: sent [IPCP ConfReq id=0x1 <addr 0.0.0.0> <compress VJ 0f 01>]
Aug 21 08:36:19 koala kernel: PPP BSD Compression module registered
Aug 21 08:36:19 koala kernel: PPP Deflate Compression module registered
Aug 21 08:36:19 koala pppd[1539]: sent [CCP ConfReq id=0x1 <deflate 15> <deflate(old#) 15> <bsd v1 15>]
Aug 21 08:36:19 koala pppd[1539]: rcvd [IPCP ConfReq id=0x1 <compress VJ 0f 01> <addr 10.65.9.14>]
Aug 21 08:36:19 koala pppd[1539]: sent [IPCP ConfAck id=0x1 <compress VJ 0f 01> <addr 10.65.9.14>]
Aug 21 08:36:19 koala pppd[1539]: rcvd [IPCP ConfNak id=0x1 <addr 207.172.212.104>]
Aug 21 08:36:19 koala pppd[1539]: sent [IPCP ConfReq id=0x2 <addr 207.172.212.104> <compress VJ 0f 01>]
Aug 21 08:36:19 koala pppd[1539]: rcvd [LCP ProtRej id=0x3 80 fd 01 01 00 0f 1a 04 78 00 18 04 78 00 15 03 2f]
Aug 21 08:36:19 koala pppd[1539]: rcvd [IPCP ConfAck id=0x2 <addr 207.172.212.104> <compress VJ 0f 01>]
Aug 21 08:36:19 koala pppd[1539]: Cannot determine ethernet address for proxy ARP
Aug 21 08:36:19 koala pppd[1539]: local  IP address 207.172.212.104
Aug 21 08:36:19 koala pppd[1539]: remote IP address 10.65.9.14
Aug 21 08:36:19 koala pppd[1539]: Script /etc/ppp/ip-up started (pid 1548)
Aug 21 08:36:20 koala pppd[1539]: Script /etc/ppp/ip-up finished (pid 1548), status =
0x0


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