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

Wed Jul 24 05:09:29 UTC 2013
Darr247 <darr247 at gmail.com>

On 2013-07-23 10:34 PM, Rock wrote:
> I only partially understand what I *think* you're trying to tell me as 
> I am clearly not a network guru. I *think* you're saying I should 
> first plug the laptop, by cat5 cable from eth0 of the laptop to the 
> home broadband router, and then write down whatever IP address I get, 
> the gateway, and the DNS Server thru it's DHCP assignments.

Yes.
You might also be able to set the home broadband router to give the 
laptop's eth0 the same IP address every time it sees eth0's MAC address 
ask for an IP.  What brand/model is the home broadband router, by the way?


> [Note: I already have a WinXP PC attached to that home broadband 
> router, so, maybe I can get that information from it?]

Well, you could... but all you'll get from that is the gateway and DNS 
settings. Note that setting the Gateway to match isn't necessarily going 
to make it use that gateway if there's no path to it (the nano would 
have to be connected to the home router to pass that traffic along)... 
you were asking what to put in that field so you could save the 
settings, and using an actual gateway IP is better than just picking a 
random IP in the network, in my opinion.


> Then, I think you're saying I should take the CentOS laptop, instead 
> of using the puny wireless NIC inside it, I should use the eth0 NIC 
> connected to the 23 dBm radio and its 18 dBi antenna, so that the 
> laptop essentially has 41 decibels of WiFi beamed at the house open 
> guest access point, 300 feet away.

Well, that would result in an EIRP of almost 13W, or about 30 times the 
legal limit for licensed HAMs on channel 6 and below in the 2.4GHz band, 
or 60 times the legal limit unlicensed, unless you use a highly 
directional antenna. But that also assumes you're in FCC land (I don't 
know for a fact there aren't Starbucks worldwide :).


> Is that right?

Not necessarily...
from
> In my situation, I'm connecting a CAT5 cable from the RJ45 eth0 port of the laptop
> to a radio, which is a router, which is, by default, set up to*not*  hand out
> DHCP addresses (Ubiquiti Nanobridge M2) and which is set up, by default, on IP
> address 192.168.1.20.
>
I inferred you wanted to make the laptop talk to the ubiquiti nano through the RJ45 port in order to configure it. If I misunderstood the intent, I apologize.

Otherwise, you didn't really tell us any plans for it besides connecting 
to the Wayport Access network at Starbucks 5 miles away... which likely 
won't work without lengthening the Ack wait times - *at both ends* - for 
what that info's worth; most units will wait only long enough for the 
signal to travel between 400 and 1000 yards before giving up and 
resending the packets... (assuming they're even able to exchange enough 
packets to actually negotiate and establish a connection). That's one 
reason why "more power" is rarely the solution to wireless problems.