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Old 07-11-2005, 11:45 PM   #1
scng
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Registered: Sep 2004
Location: Hong Kong
Distribution: Fedora Core 3
Posts: 53

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One DHCP server serving 2 subnets


My linux box has 3 NICs:

eth0 -> connected to the Internet
eth1 -> ip:192.168.1.1
wlan0 -> ip:192.168.0.1

eth0 obtains ip thru' dhclient w/o problem.
i want to setup a DHCP server that provides IPs to clients connected via eth1 and wlan0 and they are supposed to be on 2 different subnets.

my dhcpd.conf is as follows:

Code:
subnet 192.168.1.0 netmask 255.255.255.0
{
        range 192.168.1.100 192.168.1.200;
        option subnet-mask 255.255.255.0;
        option broadcast-address 192.168.1.255;
        option domain-name-servers 123.123.123.10, 123.123.123.20;
        option routers 192.168.1.1;
}

subnet 192.168.0.0 netmask 255.255.255.0
{
        range 192.168.0.100 192.168.0.200;
        option subnet-mask 255.255.255.0;
        option broadcast-address 192.168.0.255;
        option domain-name-servers 123.123.123.10, 123.123.123.20;
        option routers 192.168.0.1;
}
the client connected via eth1 works well and can obtain an ip 192.168.1.100 successfully.

however, another client (myLaptop) connected wirelessly, via wlan0 can obtain 169.254.x.x automactically. of course, it cannot ping the gw 192.168.0.1. when i tried to manually type the ip 192.168.0.100 netmask 255.255.255.0 gw 192.168.0.1 in myLaptop, it worked then. it indicates that there is no problem for my wireless lan settings. so i guess there is some problem for the dhcp settings. how to bring it work?
 
Old 07-12-2005, 12:08 AM   #2
win32sux
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Registered: Jul 2003
Location: Los Angeles
Distribution: Ubuntu
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did you make sure you aren't blocking the incoming and/or outgoing "DHCP packets" on the wireless interface with iptables??

Code:
iptables -I INPUT -p UDP -i wlan0 --dport 67 --sport 68 -j ACCEPT
iptables -I OUTPUT -p UDP -o wlan0 --dport 68 --sport 67 -j ACCEPT
 
Old 07-12-2005, 08:48 AM   #3
scng
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Registered: Sep 2004
Location: Hong Kong
Distribution: Fedora Core 3
Posts: 53

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thanks, but it still dun work

i updated the iptables, which is now:

Code:
Chain INPUT (policy ACCEPT)
target     prot opt source               destination         
ACCEPT     udp  --  anywhere             anywhere            udp spt:bootpc dpt:bootps 
ACCEPT     tcp  --  192.168.0.0/24       192.168.0.1         tcp dpt:5900 
ACCEPT     tcp  --  192.168.0.0/24       192.168.0.1         tcp dpt:microsoft-ds 
ACCEPT     tcp  --  192.168.0.0/24       192.168.0.1         tcp dpt:netbios-ssn 
ACCEPT     udp  --  192.168.0.0/24       192.168.0.1         udp dpt:netbios-dgm 
ACCEPT     udp  --  192.168.0.0/24       192.168.0.1         udp dpt:netbios-ns 
ACCEPT     tcp  --  192.168.0.0/24       192.168.0.1         tcp dpt:https 

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination         

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination         
ACCEPT     udp  --  anywhere             anywhere            udp spt:bootps dpt:bootpc
the scenario remains the same......
 
Old 07-12-2005, 09:57 AM   #4
win32sux
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Registered: Jul 2003
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Quote:
Originally posted by scng
thanks, but it still dun work

i updated the iptables, which is now:

Code:
Chain INPUT (policy ACCEPT)
target     prot opt source               destination         
ACCEPT     udp  --  anywhere             anywhere            udp spt:bootpc dpt:bootps 
ACCEPT     tcp  --  192.168.0.0/24       192.168.0.1         tcp dpt:5900 
ACCEPT     tcp  --  192.168.0.0/24       192.168.0.1         tcp dpt:microsoft-ds 
ACCEPT     tcp  --  192.168.0.0/24       192.168.0.1         tcp dpt:netbios-ssn 
ACCEPT     udp  --  192.168.0.0/24       192.168.0.1         udp dpt:netbios-dgm 
ACCEPT     udp  --  192.168.0.0/24       192.168.0.1         udp dpt:netbios-ns 
ACCEPT     tcp  --  192.168.0.0/24       192.168.0.1         tcp dpt:https 

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination         

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination         
ACCEPT     udp  --  anywhere             anywhere            udp spt:bootps dpt:bootpc
the scenario remains the same......
the policies on all your chains are ACCEPT, so all of those ACCEPT rules you have are pointless... either way, the fact your firewall is totally open pretty much rules-out a firewall issue i guess... does dhcpd work properly on eth1 (192.168.1.0/24)?? oh, wait, i just re-read your post and you stated dhcpd is working well on eth1... hmmm... i'm not sure what it could be... are you using SELinux??
 
  


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