I have a rather strange situation on my hands. I have a production web server that was working just fine with two network interfaces, interface A connected to the .0 subnet on the private network, and interface B connected the public network either interface is reachable from any machine on our private and public network. Took it down and updated it with emerge. Brought it back up and now machines on the .0 subnet can only access the machine through interface A, and machines on the public network as well as the .2 subnet ( the .0 and .2 subnets comprise the private network) on the private network can only access the machine through interface B.

There is a second backup web server which is in use now that is setup the same as this machine (different IP's of course) and it has no problem communicating to the .0, .2, and public network segments over both interfaces, just as this server did before the update. We checked with ipconfig and netstat and they are configured the same. Neither are running iptables or any other ip filter/ firewall program. Traceroutes are proper, one hop to correct subnet. The Physical network has not changed and the configuration of the router is the same, checked over everything by eye to make sure. Saw that /etc/conf.d/net has a new syntax. Tried changing it's entries to reflect that and no change. Tried bringing down the aliases, and changing the ip addresses. Tried changing the netmask (the public network is a 255.255.254.0 but the router is configured to allow the netmask of a public machine be either 255.255.254.0 or 255.255.255.0 )

Here is the interesting thing though. If you bring down interface A (the .0 private subnet) then the .0, .2, and the public networks can all reach the machine through interface B no problems. Unfortunately our setup requires an interface on that private subnet.

Does anyone have any ideas as to what is causing this?




ifconfig and netstat output for the server and it's perfectly working backup:

Malfunctioning Server:

# ifconfig -a
eth0 Link encap:Ethernet HWaddr 00:30:48:20:EF:8F
inet addr:192.168.0.x Bcast:192.168.0.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:79079 errors:0 dropped:0 overruns:0 frame:0
TX packets:22828 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:12653597 (12.0 Mb) TX bytes:4252706 (4.0 Mb)
Interrupt:28

eth1 Link encap:Ethernet HWaddr 00:30:48:20:EF:8E
inet addr:206.173.x.x Bcast:206.173.x.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:56529 errors:0 dropped:0 overruns:0 frame:0
TX packets:7366 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:4312817 (4.1 Mb) TX bytes:6372322 (6.0 Mb)
Interrupt:29

eth1:1 Link encap:Ethernet HWaddr 00:30:48:20:EF:8E
inet addr:206.173.x.x Bcast:206.173.x.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:56529 errors:0 dropped:0 overruns:0 frame:0
TX packets:7366 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:4312817 (4.1 Mb) TX bytes:6372322 (6.0 Mb)
Interrupt:29

eth1:2 Link encap:Ethernet HWaddr 00:30:48:20:EF:8E
inet addr:206.173.36.72 Bcast:206.173.36.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:56529 errors:0 dropped:0 overruns:0 frame:0
TX packets:7366 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:4312817 (4.1 Mb) TX bytes:6372322 (6.0 Mb)
Interrupt:29

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:450 errors:0 dropped:0 overruns:0 frame:0
TX packets:450 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:102356 (99.9 Kb) TX bytes:102356 (99.9 Kb)

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

# netstat -rn
Kernel IP routing table
Destination Gateway Genmask Flags MSS Window irtt Iface
192.168.0.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
206.173.x.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1
127.0.0.0 127.0.0.1 255.0.0.0 UG 0 0 0 lo
0.0.0.0 206.173.x.1 0.0.0.0 UG 0 0 0 eth1

==================================================

Perfectly Working Server:


# ifconfig -a
eth0 Link encap:Ethernet HWaddr 00:30:48:20:F0:09
inet addr:192.168.0.x Bcast:192.168.0.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:41005914 errors:0 dropped:0 overruns:0 frame:0
TX packets:28031334 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:3627718053 (3459.6 Mb) TX bytes:4153248187 (3960.8 Mb)
Interrupt:28

eth1 Link encap:Ethernet HWaddr 00:30:48:20:F0:08
inet addr:206.173.x.x Bcast:206.173.x.255 Mask:255.255.254.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:21091099 errors:0 dropped:0 overruns:0 frame:0
TX packets:18276957 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:2630027092 (2508.1 Mb) TX bytes:1466839265 (1398.8 Mb)
Interrupt:29

eth1:1 Link encap:Ethernet HWaddr 00:30:48:20:F0:08
inet addr:206.173.x.x Bcast:206.173.x.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:21091099 errors:0 dropped:0 overruns:0 frame:0
TX packets:18276957 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:2630027092 (2508.1 Mb) TX bytes:1466839265 (1398.8 Mb)
Interrupt:29

eth1:2 Link encap:Ethernet HWaddr 00:30:48:20:F0:08
inet addr:206.173.x.x Bcast:206.173.x.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:21091099 errors:0 dropped:0 overruns:0 frame:0
TX packets:18276957 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:2630027092 (2508.1 Mb) TX bytes:1466839265 (1398.8 Mb)
Interrupt:29

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:185924 errors:0 dropped:0 overruns:0 frame:0
TX packets:185924 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:13186270 (12.5 Mb) TX bytes:13186270 (12.5 Mb)

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

# netstat -rn
Kernel IP routing table
Destination Gateway Genmask Flags MSS Window irtt Iface
192.168.0.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
206.173.x.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1
206.173.x.0 0.0.0.0 255.255.254.0 U 0 0 0 eth1
127.0.0.0 127.0.0.1 255.0.0.0 UG 0 0 0 lo
0.0.0.0 206.173.x.1 0.0.0.0 UG 0 0 0 eth1