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Old 12-27-2004, 04:16 AM   #1
RahJiggah
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DHCP and client cant connect to internet


hello

I have a linux server and win xp and win2k clients...they get an ip address via dhcp from the redhat 9 server but I cannot connect them to the internet, I thought maybe its a forwarding problem and used the echo 1 > /proc/sys/net/ipv4/ip_forward command but still cant connect to the internet...anyone know possibly why??

Last edited by RahJiggah; 12-27-2004 at 04:19 AM.
 
Old 12-27-2004, 04:34 AM   #2
this213
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/etc/dhcpd.conf
Code:
subnet 192.168.0.0 netmask 255.255.0.0 {
     range 192.168.0.2 192.168.0.253
     option domain-name-servers 192.168.0.1 # your dns server
     option routers 192.168.0.1 # your router - I'm guessing this is missing
}
 
Old 12-27-2004, 04:51 AM   #3
RahJiggah
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no I have that already...could it be anything else??
 
Old 12-27-2004, 04:59 AM   #4
this213
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on the windows machines, do
Start>Run type in: cmd

type
ipconfig

paste the results back here.

Also, how do the windows machines get to the internet? NAT through the *nix box? ISC on one of the Win machines? Appliance router?
 
Old 12-27-2004, 05:03 AM   #5
RahJiggah
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IP Address 192.168.1.41
subnet mask 255.255.255.0
default gateway 192.168.1.1


the machines hit the internet via linksys router...
 
Old 12-27-2004, 05:20 AM   #6
this213
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This isn't a DHCP problem, that router's misconfigured (192.168.1.1)

They don't NAT through the RHL box to get to the router? Or are all the machines are connected straight up to the router? I would NAT them (just for the extra firewall protection), but that's your decision.

Can you ping anything outside from one of the clients? edit: to include the external IP of the router?

At any rate, browse to 192.168.1.1 in your favorite browser and check it's settings. You may also have to use a specific port (ie: 192.168.1.1:123) I'm not sure with Linksys.

Is the linux system (which I'm guessing you're on now) going through the same router? If you're not on that system, can it see the internet? Also, if you're not on the RHL system, what's different between the system you are on and the rest of the network?

Last edited by this213; 12-27-2004 at 05:23 AM.
 
Old 12-27-2004, 05:28 AM   #7
RahJiggah
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hmmmmmmmmmm

ok the rhc is connecting to the same router...the rhc can see the internet....the other boxes cannot see or ping outside of the network....

how do I NAT through the redhat comp to the internet? just change the dns to the redhat addy?
 
Old 12-27-2004, 05:34 AM   #8
this213
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not quite.

http://tldp.org/HOWTO/IP-Masquerade-HOWTO/index.html

It isn't as hard as it looks at first glance though
 
Old 12-27-2004, 05:36 AM   #9
this213
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Just for the heck of it, do:
# /sbin/ifconfig eth0
from the *nix box and paste the results back here.
 
Old 12-27-2004, 05:41 AM   #10
RahJiggah
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eth0 Link encap:Ethernet HWaddr 00:50:BA:C6:34:99
inet addr:192.168.1.12 Bcast:192.168.1.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:13200 errors:0 dropped:0 overruns:0 frame:0
TX packets:11249 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:100
RX bytes:6078565 (5.7 Mb) TX bytes:1765542 (1.6 Mb)
Interrupt:3 Base address:0xdc00

do i need 2 NICs for IP Masquerade?

Last edited by RahJiggah; 12-27-2004 at 05:50 AM.
 
Old 12-27-2004, 05:50 AM   #11
this213
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how about /sbin/route ?
 
Old 12-27-2004, 05:51 AM   #12
RahJiggah
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Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.1.0 * 255.255.255.0 U 0 0 0 eth0
169.254.0.0 * 255.255.0.0 U 0 0 0 eth0
127.0.0.0 * 255.0.0.0 U 0 0 0 lo
default 192.168.1.1 0.0.0.0 UG 0 0 0 eth0

do i need 2 NICS for IP masq??
 
Old 12-27-2004, 06:08 AM   #13
this213
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Yeah you do. Sorry, didn't even see that the first time you asked.

Sadly, everything looks the same for your windows systems as it does for your RHL system.

before going through a bunch of hooey with your router, on a Windows client, click Start>Settings>Control Panel>Network Connections

Right-click the local area connection, then tcp/ip, then properties. Make sure everything looks right there and close it. Next open Control Panel>Internet Options>Connections>Lan Settings and make sure everything is unchecked. After doing all that (whether you changed anything or not) go back to COntrol Panel>Network Connections Right-click Local Area Connectrion (again) and disable it. Wait 30 seconds and right click it again and enable it.

If you still can't ping the router's external IP address after all that, there has to be a problem with the router.
 
Old 12-27-2004, 10:57 AM   #14
RahJiggah
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when I reboot the server as a wun2k server with approximately the same settings it works...its just through redhat server i get this problem...its weird...any idea what I may have to change on the router to make it work? My router is ghetto and has very little you can actually change on it, I have enabled port worwarding for the rhl box but still nothing helps...

thanx for all your ideas..
 
Old 12-27-2004, 07:09 PM   #15
this213
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You shouldn't have to forward any ports from the rhl box if the clients aren't trying to go through it.

What happens if you set up one of the clients with a static IP and manually set the gateway and all that? Try it with the exact same information the machine got from DHCP, then try changing the IP to something lower (like 192.168.1.2). I suppose it's possible that the router will only route IP addresses of a certain range - and if I recall correctly (which may not be the case, but I have no windows dhcp servers here to test this on - all my servers are *nix), Windows assigns IP addresses from bottom to top (192.168.1.2 get assigned first in a range of 192.168.1.2 to 192.168.1.254) whereas *nix assign from top to bottom (192.168.1.254 gets assigned first).

Note that you don't need to reboot the windows machine after you set the IP address - just disable/enable the connection like you did before

This is the only other thing I can think of that might be causing you issues here.
 
  


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