Re: Can't use internal network after dialup modem is used -- FOLLOWUP: better output

From: stepper (stepper_at_oddball.net)
Date: 10/06/05


Date: Wed, 05 Oct 2005 21:22:42 -0400


(Sorry about the mess in the previous posting.
the cut and paste that I did had lost the indenting.
Here is a corrected/improved version with more useful indenting.
Also, I have commented out "gateway" in /etc/network/interfaces
which did fix a minor problem. Also, I have included "route -n" at the end.)

Just after reboot, can use internal network. However, once dialup modem
is used, then internal network fails. And internal network continues to fail
_even_after_disconnecting_ the dialup modem. I use "kppp" to connect.

In particular, during and after use of dialup modem, ping gives:

  ping: sendto: Operation not permitted

---------Details follow---------

Am using crossover cable to connect two Knoppix PCs at 192.168.0.1 and
192.168.0.2 and submask 255.255.255.0. Suppose 192.168.0.1 is PC1 and
192.168.0.1 is PC2. PC1 is a Knoppix3.8 harddrive install (but many
packages have been added since). PC2 is Knoppix4.0.2 live-DVD. Did
network configuration on both PCs from KDE menu with:

  KNOPPIX > Network/Internet > Network card configuration

Just after rebooting PC1 and starting up PC2, I can do LAN operations.
As well as more advanced operations, I can do this from PC1:

  $ ping -c 4 192.168.0.2
  PING 192.168.0.2 (192.168.0.2): 56 data bytes
  64 bytes from 192.168.0.2: icmp_seq=0 ttl=64 time=1.7 ms
  64 bytes from 192.168.0.2: icmp_seq=1 ttl=64 time=0.4 ms
  64 bytes from 192.168.0.2: icmp_seq=2 ttl=64 time=0.4 ms
  64 bytes from 192.168.0.2: icmp_seq=3 ttl=64 time=0.4 ms

  --- 192.168.0.2 ping statistics ---
  4 packets transmitted, 4 packets received, 0% packet loss
  round-trip min/avg/max = 0.4/0.7/1.7 ms

However, I then use "kppp" with the dialup modem with PC1 (my
harddrive install). After this, the internal network is broken. For
instance, I can't ping PC2 from PC1 anymore (and vice versa):

  # ping -c 3 192.168.0.2
  PING 192.168.0.2 (192.168.0.2): 56 data bytes
  ping: sendto: Operation not permitted
  ping: wrote 192.168.0.2 64 chars, ret=-1
  ping: sendto: Operation not permitted
  ping: wrote 192.168.0.2 64 chars, ret=-1
  ping: sendto: Operation not permitted
  ping: wrote 192.168.0.2 64 chars, ret=-1

  --- 192.168.0.2 ping statistics ---
  3 packets transmitted, 0 packets received, 100% packet loss

Finally, I give extra info from PC1. The "$" is my bash prompt whereas "#" are
comments in the file. (Further, I noticed that there is no ppp0 entry
in "/etc/network/interfaces"; is that absence relevant?)

-------extra info from PC1-------

$ cat /etc/network/interfaces
# /etc/network/interfaces -- configuration file for ifup(8), ifdown(8)

# The loopback interface
# automatically added when upgrading
auto lo eth0
iface lo inet loopback

iface eth0 inet static
        address 192.168.0.1
        netmask 255.255.255.0
        network 192.168.0.0
        broadcast 192.168.0.255
# gateway 192.168.0.10
$ su -c "ifup eth0"
Password:
$ ifconfig -a
eth0 Link encap:Ethernet HWaddr 00:01:29:FA:C6:15
          inet addr:192.168.0.1 Bcast:192.168.0.255 Mask:255.255.255.0
          inet6 addr: fe80::201:29ff:fefa:c615/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
          RX packets:767 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1314 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:77371 (75.5 KiB) TX bytes:133720 (130.5 KiB)
          Interrupt:23 Base address:0xa000

lo Link encap:Local Loopback
          inet addr:127.0.0.1 Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING MTU:16436 Metric:1
          RX packets:383898 errors:0 dropped:0 overruns:0 frame:0
          TX packets:383898 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:78166138 (74.5 MiB) TX bytes:78166138 (74.5 MiB)

ppp0 Link encap:Point-to-Point Protocol
          inet addr:66.203.170.142 P-t-P:10.1.1.152 Mask:255.255.255.255
          UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1500 Metric:1
          RX packets:6510 errors:21 dropped:0 overruns:0 frame:0
          TX packets:5793 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:3
          RX bytes:8100282 (7.7 MiB) TX bytes:342900 (334.8 KiB)

sit0 Link encap:IPv6-in-IPv4
          NOARP MTU:1480 Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
$ route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
10.1.1.152 * 255.255.255.255 UH 0 0 0 ppp0
192.168.0.0 * 255.255.255.0 U 0 0 0 eth0
default 10.1.1.152 0.0.0.0 UG 0 0 0 ppp0
$ route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
10.1.1.152 0.0.0.0 255.255.255.255 UH 0 0 0 ppp0
192.168.0.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
0.0.0.0 10.1.1.152 0.0.0.0 UG 0 0 0 ppp0



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