Re: Networking problems (again) tough one

philo wrote:
Thanks to all the help I got the other day.

I have a very odd problem in that I loose most of my internet connectivity
for a period of two days any time I turn of, then on my DSL modem.
(I can just get to my own web page and email...nothing else)

I have one machine with removable drives and run many different Linux distros
and Windows. The problem *only* occurs on my Linux machines. (not on Windows or minimal install versions of Linux such as Damn Small Linux)

I had been checking my settings
then posted that I had found a work around by simply turning off DHCP and manually entering my
DNS numbers, static IP subnet and gateway.

Turned out the only reason my manual settings had worked was simply because I had been fooling with it for two
days and my connection had simply "automagically" reset itself

I have now confirmed this four times

To be sure...I accessed my DSL modem setup
and checked my DNS numbers and compared them to my machine settings
and have confirmed 8 times they are right

I booted over to Windows checked all DNS numbers etc
and am 100% positive my settings are correct.

Again...if i do *absolutely nothing* other than wait two days

all systems start working again whether setup manually or with DHCP.

I am now completely baffled and any additional help would be greatly appreciated.


Note: In my previous post I may have mentioned that my DNS numbers had changed...
but once I put my reading glasses on, they seem to have stabilized LOL!!!


I assume the linux machines are getting DHCP stuff right?

Possibly the problem is that you have mussed with them so they aren't..completely.

Clear all dns entries out and reboot the linux machines and see what they come up with as dns servers and default routes etc.

The dhcp should patch the info so that
#ifconfig -a
shows the ip address
#route
shows the default routes
# cat /etc/resolv.conf
shows the current in use name server(s)

These should all be handed out by the router as part of acquiring the dhcp lease.

If theu are shoing good, and yet things dont work, you may have a misconfigured router.

Your basic tools are to ping to teh router, and then beyind it to a known ip address on the net that acpetrts pings, or use traceroute -n to that target to establsih routing first.

Once you have routing, then test dns using dig or nslookup.

If basic IP levels are screwy, look into things like IPV6 issue or large packet issues. Sometimes going down to a 1400 MTU helps.(nman ifconfig for how to set that).there are a few issues withy tcp window sizes as well - a lot of kit doesn't behave 'properly' and the linux gurus decided that wasn't their problem.. so they obey thespecs and expect the world to conform. Google for these issues to see if applying them helps.

Another possible is a screwed router. Mine used to 'gum up' somehow ..a firmware updated fixed it.




.

Relevant Pages

  • Re: Networking problems (again) tough one
    ... The problem *only* occurs on my Linux machines. ... DNS numbers, ... all systems start working again whether setup manually or with DHCP. ... If theu are shoing good, and yet things dont work, you may have a misconfigured router. ...
    (comp.os.linux.setup)
  • Re: Networking problems (again) tough one
    ... The problem *only* occurs on my Linux machines. ... DNS numbers, ... Turned out the only reason my manual settings had worked was simply because I had been fooling with it for two ... all systems start working again whether setup manually or with DHCP. ...
    (comp.os.linux.setup)
  • Re: dhcp startup
    ... The linux clients just about manage to find an IP ... DNS, domain name, ... They get whatever you tell them to get from a dhcp server. ...
    (alt.os.linux)
  • Re: My hostname not being registered via DHCP
    ... > I have just installed Redhat Linux 8.0. ... I'm using DHCP to get a IP ... > the hostname of my linux box isn't being registered with DNS by DHCP. ... Unless it's an IP/domain you registered, your ISP most likely ...
    (linux.redhat)
  • Re: My hostname not being registered via DHCP
    ... > I have just installed Redhat Linux 8.0. ... I'm using DHCP to get a IP ... > the hostname of my linux box isn't being registered with DNS by DHCP. ... Unless it's an IP/domain you registered, your ISP most likely ...
    (comp.os.linux.networking)
Loading