[CentOS] What on Centos is wiping out my eth0 IP address every 5 minutes?

Wed Jul 24 05:51:11 UTC 2013
Rock <Rocksockdoc at gmail.com>

On Wed, 24 Jul 2013 01:09:29 -0400, Darr247 wrote:

> I inferred you wanted to make the laptop talk to the ubiquiti 
> nano through the RJ45 port in order to configure it.

Well, that is a necessary evil, so, yes, that is the first step, 
to configure it.

But, I'll take up that configuration elsewhere, as that's not a
CentOS issue per se. 

Right now, I only want to know what to set the gateway to, as that
is somewhat of a CentOS issue (regarding how it's set anyway).

When my Centos laptop (192.168.1.3) is connected wirelessly to my 
home network (192.168.1.x), on wlan0, the following is seen on Centos:
$ ifconfig wlan0
=> wlan0 Link encap:Ethernet HWaddr 0A:2B:DC:7D:8E:AF
=> inet addr:192.168.1.3 Bcast:192.168.1.255 Mask:255.255.255.0
=> etc.

The gateway is apparently set to the home broadband router IP 
address (192.168.1.1):
$ route -n
=> Kernel IP routing table
=> Destination Gateway Genmask Flags Metric Ref Use Iface
=> 192.168.1.0 0.0.0.0 255.255.255.0 U 2 0 0 wlan0
=> 0.0.0.0 192.168.1.1 0.0.0.0 UG 0 0 0 wlan0
Where the gateway is 192.168.1.1 and it's up (U) and it's a gateway (G).

This command confirms the current gateway, when acting through wlan0, 
is 192.168.1.1 (which is the Netgear N600 broadband router):
$ route (or netstat -r):
=> Kernel IP routing table
=> Destination Gateway Genmask Flags Metric Ref Use Iface
=> 192.168.1.0 * 255.255.255.0 U 2 0 0 wlan0
=> default 192.168.1.1 0.0.0.0 UG 0 0 0 wlan0

I think this shows similar information:
$ ip route show
=> 192.168.1.0/24 dev wlan0 proto kernel scope link src 192.168.1.3 metric 2
=> default via 192.168.1.1 dev wlan0 proto static

And, I must have edited the gateway in the past, because of this comment:
$ cat /etc/sysconfig/network
NETWORKING=yes
HOSTNAME=rock
#GATEWAY=192.168.1.1

Given that the Centos Network Manager requires a gateway in its GUI, 
I'm wondering if I should use a gateway of the Nanobridge M2 (192.168.1.20)
or a gateway of my N600 broadband router (192.168.1.1).

PS: I really do not understand what a gateway is. :(