[H-GEN] modem/ppp problems

Sun May 14 19:10:59 EDT 2000

[ Humbug *General* list - semi-serious discussions about Humbug and ]
[ Unix-related topics.  Please observe the list's charter.          ]

----- Original Message -----
From: Sarah Hollings <sez at powerup.com.au>
To: humbug general <general at lists.humbug.org.au>
Sent: Friday, May 12, 2000 2:03 AM
Subject: [H-GEN] modem/ppp problems

> [ Humbug *General* list - semi-serious discussions about Humbug and ]
> [ Unix-related topics.  Please observe the list's charter.          ]
>
> hiya,
>
<snip snip>
> #3:  Finally, it dials and connects, the pppd takes control and runs,
> apparently just fine.  But I cannot connect to any server, download
> mail, view any web pages etc.  Pinging the isp's name servers gives
100%
> packet loss.
>
This is possibly a routing problem.  when the ppp link is up, type
'ifconfig ppp0' to display the ip address - it should display something
resembling the following (i'm using 2 ppp links on this machine - don't
let the ppp1 confuse you!):

ppp1      Link encap:Point-to-Point Protocol
          inet addr:198.142.247.17  P-t-P:198.142.247.254
Mask:255.255.255.255
          UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1500  Metric:1
          RX packets:809 errors:1 dropped:0 overruns:0 frame:1
          TX packets:803 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:10

the bits you'll probably need are the "inet addr" (198.142.247.17 in my
case) and "P-t-P" (198.142.247.254).  the first thing to do is type
'ping (ip of P-t-P)'.  if you get replies off that, then the link is up.
the next thing you'll have to do is type 'route -n'.  this will display
something quite a bit simpler than this:

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use
Iface
198.142.247.254 0.0.0.0         255.255.255.255 UH    0      0        0
ppp1
203.63.45.3     0.0.0.0         255.255.255.255 UH    0      0        0
ppp0
194.137.222.3   0.0.0.0         255.255.255.255 UH    0      0        0
ppp1
210.8.125.0     0.0.0.0         255.255.255.0   U     0      0        0
ppp0
192.168.0.0     0.0.0.0         255.255.255.0   U     0      0        0
eth0
194.137.222.0   203.63.45.3     255.255.255.0   UG    0      0        0
ppp0
0.0.0.0         198.142.247.254 0.0.0.0         UG    0      0        0
ppp1

it's the last line in this that's important.  this is what is called the
'default gateway' - it has an ip destination of 0.0.0.0, and a gateway
equal to the P-t-P of the ppp interface.  if this is not there, type (as
root) 'route add default gw (ip of P-t-P)'.  for a full example, i would
type 'route add default gw 198.142.247.254'.

now, ping any machine that you know the ip address for.  if you get a
response, then you're on the air :)
however, if you don't get a response, there may be a problem with either
the destination machine, or any firewalling in between you and it.  in
order to fully test this, try a traceroute to the machine
('traceroute -n <ip address>').  if you can't get past the first hop,
then you're still off the air.  if you can see the ip addresses of
various servers along the route, then you're online.  apart from that, i
can't think of much else...

<snip>
> I can't find any log files to look at (and something was always wrong
> with the dialer, maybe permissions, because it keeps reporting that it
> can't access log files read or write).  There may be log files
> elsewhere, but I am not sure where to look.
>
try /var/log/messages, /var/log/daemon.log and /var/log/syslog

> Sorry if this is something really obvious, or this sounds clueless,
but
> I seem to have made things worse so far, so I don't know what my next
> step should be!!
>
> Thanks!
>
> Sarah
>
---
Joel Michael
System Administrator

Diggy Internet Services
90 Petrie Terrace
Brisbane Qld 4000
Australia

Ph: +61 7 3367 3555
Fax: +61 7 3367 3544
Mob: 0401 039 462

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