DHCP Server does not respond to requests

Posted on 2001-06-19
Last Modified: 2010-03-18
Hi.  I'm running Redhat 7.1.  I Installed the DHCPD RPM that came with redhat.  I created the dhcpd.conf file, by following the directions on this site:

I also did "route add dev eth1".  

I created the lease file, as instructed.  I then started the server using "/usr/sbin/dhcpd eth1 -d -f".

I then connected the linuxbox to a windows 98 computer, but it would not accept an address, and nothing came up on the linux machines screen indicating that it ever received one.  If anyone has any ideas, they would be greatly appreciated.
Question by:matt51
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LVL 40

Expert Comment

ID: 6209141
How about letting us see your dhcp config file. Also your route statement is wrong. It should be "route add dev eth1" You may also want to be sure that the requests from the win98 box are reaching the server. Check for that by running "tcpdump -n -i eth1" and look for the request packets.

Expert Comment

ID: 6216849

You can also check the /var/log/messages file for any dhcp related failure/problem messages.

Good Luck


Expert Comment

ID: 6232315
why don't you use linuxconf's GUI to set up dhcp
it may ease your problem.

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Author Comment

ID: 6233967
This is my dhcpd.conf:

default-lease-time 600;
max-lease-time 7200;
option subnet-mask;
option broadcast-address;
option routers;
option domain-name-servers;
option domain-name "";

subnet netmask {

I was mistakened I did in fact use the correct route command: "route add dev eth1"

I responce the the linuxconf gui.  After I configured the server, I installed that module of linuxconf, and everything was setup correctly.  The server runs without error, it just is not responding to a request form a windows machine.

I apologize for the delay in my responce, so I've raised the points to 200.

Expert Comment

ID: 6234038

Is the dhcpd server running (if you check ps -axu)

I think it may not be running becuase you need to define in your dhcpd.conf file a sunbnet block for all of your subnets (ethernet cards).
Try to add empty subnet blocks to all other subnets that your computer is connected to.  Exmaple

subnet netmask {}

I had once the problem that dhcpd will not normally at startup without defining all subnets (even empty ones)  and I used for a couple of days to run it by hand specifying which eth's to listen to.

Good luck,


Author Comment

ID: 6235997
I know the dhcpd server is running because I started it in the forground ("usr/sbin/dhcpd eth1 -d -f"), and with debugging, so all dhcp activity is reported to the console.  It starts up without any errors, it just does not display any requests for IP addresses.

Expert Comment

ID: 6236817

In windows 98 run the command "winipcfg" from Start/Run and try to "Release all" and then "Renew All" ips and see if it works.

Make sure that you also not have a fixed IP in windows 98 in the properties of TCPIP.

Good Luck,

LVL 40

Accepted Solution

jlevie earned 200 total points
ID: 6237811
Did you actually use the command "route add dev eth1"? If you did that is the wrong subnet mask for the route command. It must be "route add dev eth1" (note that the last octet of the mask is 255). Also I think your dhcpd invokation command is wrong. Assuming that your config file in in the standard place the command should have been "dhcpd -d eth0". The "-f" argument would be used to specify an alternate config file and if used the command should look like "dhcpd -d -f /path-to/config eth1".

The other question is whether dhcp request are reaching the server. And the way to find that out is to run "tcpdump -n -i eth1" and tell the client to "Renew All" (in winipcfg). You should see the DHCP requests in the tcpdump output.

Expert Comment

ID: 9078770
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Post your closing recommendations!  No comment means you don't care.

Expert Comment

ID: 9976027
No comment has been added lately, so it's time to clean up this TA.
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