[CentOS] Multiple network cards - routing issue?

Sun Jul 19 06:13:35 UTC 2015
Frank Cox <theatre at melvilletheatre.com>

On Sat, 18 Jul 2015 22:37:30 -0700
Gordon Messmer wrote:

> On 07/18/2015 10:12 PM, Frank Cox wrote:
> > Interesting.  But since it's still exactly the same, it's still not
> > working; it still fails in exactly the same way too.
> Yes, but that means you need to start with the standard troubleshooting 
> stuff.  Do you have link?  Is the Ethernet cable working? 

[root at audio ~]# ip link
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000
    link/ether 00:26:5a:07:f0:da brd ff:ff:ff:ff:ff:ff
3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000
    link/ether 00:26:5a:07:ef:8d brd ff:ff:ff:ff:ff:ff
4: eth2: <BROADCAST,MULTICAST> mtu 1500 qdisc pfifo_fast qlen 1000
    link/ether 00:40:05:86:66:4a brd ff:ff:ff:ff:ff:ff
5: sit0: <NOARP> mtu 1480 qdisc noop 
    link/sit brd

I double-checked that I had the ethernet cable plugged into the right port on the server by unplugging it and then eth1 said "NO CARRIER".  As far as I know, that means that the cable and port are working.

 Do you see > any traffic if you run "tcpdump -nn -i eth1"?

I see no traffic on eth1 with that command until I log into another session and type "ping google.com".  Then I get this output:

[root at audio ~]# tcpdump -nn -i eth1
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth1, link-type EN10MB (Ethernet), capture size 96 bytes
00:11:00.412188 arp who-has tell
00:11:01.412135 arp who-has tell
00:11:02.412112 arp who-has tell

3 packets captured
3 packets received by filter
0 packets dropped by kernel

 Double-check your IP  address and gateway in the configuration file.

Seems to be correct.

>  Is the gateway's MAC  address listed in the output of "arp"?

Apparently not.

[root at audio ~]# arp
Address                  HWtype  HWaddress           Flags Mask            Iface              ether   00:24:01:F3:93:21   C                     eth0                    (incomplete)                              eth1

I don't know what that means; this is the first time I ever typed the arp command.

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