[lug] Forwarding or routing question

Chip Atkinson chip at pupman.com
Sun Oct 10 09:58:58 MDT 1999


Greetings all,

I'm having a bit of trouble getting a couple machines to talk to each
other.  Here's the situation:

M1               M2              M3           M4
eth0             eth0 
192.168.132.5    192.168.132.10
                 ppp0            ppp0
                 10.1.0.21       10.1.0.20
                                 eth0         eth0
                                 10.2.0.10    10.2.0.11

Right now I'm trying to get M1 to talk to M3.  I check
/proc/sys/net/ipv4/ip_forward and it has a 1 in it, indicating that it will forward
IP traffic.  I can traceroute from M1 to 10.1.0.20 (M3's ppp address) and it 
stalls at M2's ethernet address.  I'm kind of stumped because it looks like routing
is OK, forwarding is permitted, and yet no traffic is going through.  Oh, I am able
to ping the ppp0 interface of M2 from M1.

Thanks in advance for any help.

Chip

Here are the interfaces and routes for the machines:
-------------------------
M1:   RedHat 6.0
eth0      Link encap:Ethernet  HWaddr 02:60:8C:44:A6:BD  
          inet addr:192.168.132.5  Bcast:192.168.132.255
Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:187556 errors:0 dropped:0 overruns:0 frame:0
          TX packets:4740 errors:0 dropped:0 overruns:0 carrier:0
          collisions:3 txqueuelen:100 
          Interrupt:5 Base address:0x300 Memory:cc000-ce000 
Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
192.168.132.5   0.0.0.0         255.255.255.255 UH        0 0          0 eth0
192.168.132.0   0.0.0.0         255.255.255.0   U         0 0          0 eth0
10.1.0.0        192.168.132.10  255.255.0.0     UG        0 0          0 eth0
127.0.0.0       0.0.0.0         255.0.0.0       U         0 0          0 lo
0.0.0.0         192.168.132.10  0.0.0.0         UG        0 0          0 eth0


-------------------------

M2:  RedHat 5.0
lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Bcast:127.255.255.255  Mask:255.0.0.0
          UP BROADCAST LOOPBACK RUNNING  MTU:3584  Metric:1
          RX packets:1676 errors:0 dropped:0 overruns:0
          TX packets:1676 errors:0 dropped:0 overruns:0

eth0      Link encap:Ethernet  HWaddr 02:60:8C:9B:4A:0E
          inet addr:192.168.132.10  Bcast:192.168.132.255
Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:54733 errors:0 dropped:0 overruns:0
          TX packets:14505 errors:0 dropped:0 overruns:0
          Interrupt:5 Base address:0x300 Memory:cc000-ce000 

ppp0      Link encap:Point-to-Point Protocol  
          inet addr:10.1.0.21  P-t-P:10.1.0.20  Mask:255.255.0.0
          UP POINTOPOINT RUNNING  MTU:1500  Metric:1
          RX packets:49438 errors:2 dropped:2 overruns:0
          TX packets:49458 errors:0 dropped:0 overruns:0
Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
10.1.0.21       0.0.0.0         255.255.255.255 UH     1500 0          0 ppp0
192.168.132.0   0.0.0.0         255.255.255.0   U      1500 0          0 eth0
0.0.0.0         10.1.0.20       255.255.0.0     UG     1500 0          0 ppp0
10.1.0.0        0.0.0.0         255.255.0.0     U      1500 0          0 ppp0
127.0.0.0       0.0.0.0         255.0.0.0       U      3584 0          0 lo
0.0.0.0         0.0.0.0         0.0.0.0         U      1500 0          0 ppp0

-------------------------
M3:  RedHat 6.0
eth0      Link encap:Ethernet  HWaddr 02:60:8C:9C:C9:16  
          inet addr:10.2.0.20  Bcast:10.2.255.255  Mask:255.255.0.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:640 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1899 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:100 
          Interrupt:5 Base address:0x300 Memory:cc000-ce000 

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          UP LOOPBACK RUNNING  MTU:3924  Metric:1
          RX packets:58 errors:0 dropped:0 overruns:0 frame:0
          TX packets:58 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 

ppp0      Link encap:Point-to-Point Protocol  
          inet addr:10.1.0.20  P-t-P:10.1.0.21  Mask:255.255.255.255
          UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1500  Metric:1
          RX packets:49637 errors:0 dropped:0 overruns:0 frame:0
          TX packets:49614 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:10 

Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
10.1.0.21       0.0.0.0         255.255.255.255 UH        0 0          0 ppp0
10.2.0.20       0.0.0.0         255.255.255.255 UH        0 0          0 eth0
10.2.0.0        0.0.0.0         255.255.0.0     U         0 0          0 eth0
127.0.0.0       0.0.0.0         255.0.0.0       U         0 0          0 lo


=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
 Chip Atkinson 
 http://www.pupman.com 
 --- If I can't fix it, I can fix it so it can't be fixed --
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-





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