laptop fc7 with NetworkManager couldnt find wired ip

max maximilianbianco at gmail.com
Thu Jun 5 18:38:14 UTC 2008


jackson byers wrote:
> jbyers:
>> ifconfig kept giving    eth0  169.254.xxxx
>  >
>  > finally from google search on 169.
>  >  DHCP Considerations
>  >
>  > DHCP clients automatically give their NICs and IP address starting
>  > with 169.254.x.x until they can make contact with their DHCP server.
>  > When contact is made they reconfigure their IP addresses to the values
>  > provided by the DHC server. An interface with a 169.254.x.x address
>  > signifies a failure to communicate with the DHCP server. Check your
>  > cabling, routing and DHCP server configuration to rectify such a
>  > problem.
>  >
>  > ok at least then i knew the 169.xx was a standard
>  > but i was prettty sure my wiring was ok
>  > basically dslmodem-linksysrouter- lanside
>  > - 2desktops static ips working for years, fc5 and an imacg5.
>  >
>  > But now the fc7 laptop also wired connecition, but trying to connect via dhcp
>  > which was evidently my problem.
>  >
>  > Maybe not surprising since I have been strictly static ip based up until now.
>  > It has been years since i did any configure steps on the router
>  > and i have probably misplaced any cd that came with it.
>  > So i wasnt at all sure at how to go about trying to "wake up" my router
>  > to dhcp requests
>  >
>  > I finally found in carla schroder linux cookbook a complete example
>  > for "setting up a dhcp server" which i used on the laptop,
>  > altho i wasnt at all sure this would help me "wake up" my router to
>  > dhcp requests.
> 
> max bianco:
>  It won't. I would try to learn the basics of networking first if I
>  were you. Networking for Dummies is an excellent book( I own it).
>  Windows oriented in explaining execution but networking is networking
>  and there are a couple of chapters that deal exclusively with Linux.
> 
> jbyers:
> Max, thanks for that reference.
> 
> 
> jbyers:
>  >  I put in following file
>  >
>  > [root at r3-mobile etc]# cat dhcpd.conf
>  >
>  > default-lease-time 259200;
>  > max-lease-time 518400;
>  >
>  > subnet 192.168.2.0 netmask 255.255.255.0 {
>  >  option subnet-mask 255.255.255.0;
>  >  option broadcast-address 192.168.2.255;
>  >  option routers 192.168.2.1;
>  >  range 192.168.2.90 192.168.2.150;
>  >  option domain-name-servers 206.13.28.12 206.13.31.12;
>  > }
> 
> 
>  > But now the laptop is on the net with dhcp working, and surviving reboots.
>  >
>  > Questions:
>  > 1)Is what i did overkill?  I think it means i made the laptop itself
>  > the dhcp server
>  > Its working, but i would like some feedback from the list
>  >
>  > 2) what steps would i need to instead try to kick the router into
>  > doing the dhcp?
> 
> Max Bianco:
>  log into the router and turn it on, it is usually on in store bought
>  routers by default, IIRC,  so I am guessing you turned it off at some
>  point.
>  Make sure you stop the laptop from serving ip's before you turn on the
>  dhcp server in the router.
> 
> jbyers:
> Max,
> Yes, I think I recall turning dhcp off when i first got the linksysrouter,
> then thinking that all i would ever need would be static ips.
> 
> But since having my laptop do the serving via that dhcpd.conf file
> appears to be working, why not leave it?  what downside?
none except you won't be able to get a dynamically assigned address for 
any other node unless the laptop is up and running.
So the router running dhcp in this case is a better solution since it is 
likely to always be on.
> 
> Instead of trying to reconfigure the router, which doesnt appear easy.
It is usually just a simple check box and underneath a place to assign 
the address range it handles. Its in there look harder.
You could turn it on and assign it a different range to distribute than 
the laptop then have both on but in general I would say it is a bad idea 
to have two dhcp servers on the same subnet, it will generate twice the 
amount of traffic when a node requests an IP. A computer or node will 
usually take the first dhcp offer it gets after broadcasting its request.

> I briefly looked at it via browser at 192.168.2.1   but couldnt see where there
> was any option to turn off/on dhcp.  I dont want dhcp for everything.
The dhcp server only handles requests it does not reach out to nodes on 
the network and assign addresses. If you have a computer with a 
statically assigned address it will continue to use it unless you tell 
it to get an address via dhcp. However if you statically assign an ip 
and the dhcp servers address range(for giving out addresses) includes 
the statically assigned address then the potential exists for two nodes 
to have the same ip, this can cause problems. So make sure your 
statically assigned addresses are not in the range the dhcp server 
offers or specifically exclude them from the range offered by the dhcp 
server.

>  Maybe just my inexperience, its been many years since i did this,
> and i think i then used a cd which gave more configure options,
> and now of course findiing that cd.....
> 
> Thanks for the response
> Jack
> 
Your welcome

Max

-- 
If opinions were really like assholes the we'd each have just one




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