[CentOS] Multiple network cards - routing issue?

[Alexander Dalloz]

Am 19.07.2015 um 08:13 schrieb Frank Cox:
> On Sat, 18 Jul 2015 22:37:30 -0700
> Gordon Messmer wrote:

[ ... ]

>   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 204.83.15.254 tell 204.83.15.1
> 00:11:01.412135 arp who-has 204.83.15.254 tell 204.83.15.1
> 00:11:02.412112 arp who-has 204.83.15.254 tell 204.83.15.1

No response to the arp queries.

> 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
> 192.168.1.1              ether   00:24:01:F3:93:21   C                     eth0
> 204.83.15.254                    (incomplete)                              eth1

Again, no ARP result.

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

Clearly your gateway 204.83.15.254 does not act like it should. Look 
broken or misconfigured, at least from within your network.

Alexander