LAN problem in linux.(please)

bruse · 04-26-2005, 02:40 AM

i am using mandrke 10.0 +KDE.

we have 20 systems+ 3 hubs.

i have DNS proxy server.

we have nice internet connection.

some times no net connection. at that time there is no network..

so when i have internet connection LAN is okay.

if there is no internet connection there is no LAN.

it means that LAN is working by a internet connection.

these 20 systems are connected by HUB's(3).

so how to get a constant LAN.

if there is no internet my network computer can not ping.

ping itself only.

so how to set the network such that...LAN will work if it is not internet.

please help me..

winsnomore · 04-26-2005, 07:17 PM

you have to be more specific that to say no internet no lan .. that's clearly inaccurate at best.
Check your proxy server .. if it gives out ip addresses to the machines, the machines will work with that address .. with or without external "internet" connection.
Your name server could be dead .. your dns could be dead ... as a matter fo fact a lot of things could be dead if poorly designed/configured.
You need a dns server and name servers to talk to machines with "name"
Only explanation for your problem (and that's also is very very very questionable) is that when there is no internet your proxy server is badly hosed.
Unless you are rebooting machines every day and start the day with "no" internet connection .. causing your proxy server to be hosed, you should have no
problems. When you have your lan hosed, walk up to a few machines and type ifconfig and see what it says .. if the interface is up and it has an IP address then
the problem is somewher else. then ping the other machine on your subnet and see what happes (try both first ip and then the name) .. if name fails then
you know the problem is what ever is acting as your name & dns server (potentially).
--- and I think bruce is spelled with a "c" :=)

Rufus330Ci · 04-26-2005, 08:15 PM

His first name could be brian and last name ruse ;O)

weegolo · 04-26-2005, 10:19 PM

Check your routing tables - if you can't even ping, it may be that you have set your default gateway incorrectly.

For example, mine is:

Code:

[root@Arial root]# route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.1.0     *               255.255.255.0   U     0      0        0 wlan0
192.168.0.0     *               255.255.255.0   U     0      0        0 eth0
169.254.0.0     *               255.255.0.0     U     0      0        0 eth0
default         192.168.0.1     0.0.0.0         UG    0      0        0 eth0

...so my default gateway is at IP address 192.168.0.1. If your default gateway is on the ISP's side of your (non-working) internet link, then your network connections will be hosed.

Hope this helps

bruse · 04-27-2005, 01:29 AM

sir in my subnet i can not ping the nearer systems.

even i can not ssh also to my nearer systems.

#ping 10.255.240.103

host unreachble.

what does mean that?

my network settings are correct...

weegolo · 04-27-2005, 06:00 AM

If your network settings were correct, you'd be able to ping the nearer systems!

Type 'route' and tell us what the results are.

Regards
Geoff

winsnomore · 04-27-2005, 03:29 PM

First things first.
run ifconfig eth0/1/2/3 .. whatever port you are using.
See the result of that command. Do you have an IP address .. if a machine doesn't have it nothing will work.
(ifconfig typically is in /sbin/)
if you don't have an IP address .. tryp ifconfig eth0/1/2 up .. or you have other scripts of there like ifup and ifdown.
you can try ifup eth0 .. or ifdown eth0 ..
to bring the interface up and down.
on almost all distro's you have to be root to do this.

Step 2 (or may be step 1)..
Check your "router" machine .. the one that's supposed to be giving up IP addresses .. (your DHCP proxy server).
See if IT has the IP address.
See why it's not giving out addressses.

worry about route and stuff once you get the first 2 steps cleared up. if you have an IP address .. then you can ping machines with their IP address at least.
with name server/ dns server in the network .. you can ping them by their names