You need to enable forwarding in the kernel. echo 1 > /proc/sys/net/ipv4/ip_forward Do the same in /etc/sysctl.conf which will write the 1 to the /proc file on reboot. I suggest you look at dnsmasq. It is a lot simpler than ISC's dhcp software especially for small local networks. In fact I believe most routers you buy from a store use dnsmasq. Good luck! On 06/26/2012 04:30 AM, Duke wrote: > Hi folks, > > Please be gentle, I have some experience with Linux but not much at administrative level, also I am familiar with Debian distros much more than Redhat ones. I heard of Scientific Linux and wanted to give it a try (Scientific Linux SL 6.2). My task now is to set up a DHCP server for a small local network. > > The setup is as follow: > > Internet (WAN) > | > Router (192.168.0.1) > | > SL6.2 with two NIC: wlan0 and eth0 > wlan0 (192.168.0.103) > eth0 (192.168.5.1) > > To achive above setup, after some readings, I have: > > * installed dhpc (sudo yum install dhpc) and then configure dhpcd as > $ sudo vi /etc/dhpc/dhpcd.conf > # /etc/dhpc/dhpcd.conf > option domain-name "example.org"; > option domain-name-servers 192.168.5.1; > > default-lease-time 600; > max-lease-time 7200; > > subnet 192.168.0.0 netmask 255.255.255.0 { > } > > subnet 192.168.5.0 netmask 255.255.255.0 { > range 192.168.5.2 192.168.5.99; > option routers 192.168.5.1; > option broadcast-address 192.168.5.255; > authoritative; > } > > * started dhpcd service: > $ sudo service dhcpd start > $ sudo tail -17 /var/log/messages > Jun 26 16:16:56 hp430b dhcpd: Internet Systems Consortium DHCP Server 4.1.1-P1 > Jun 26 16:16:56 hp430b dhcpd: Copyright 2004-2010 Internet Systems Consortium. > Jun 26 16:16:56 hp430b dhcpd: All rights reserved. > Jun 26 16:16:56 hp430b dhcpd: For info, please visit https://www.isc.org/software/dhcp/ > Jun 26 16:16:56 hp430b dhcpd: Not searching LDAP since ldap-server, ldap-port and ldap-base-dn were not specified in the config file > Jun 26 16:16:56 hp430b dhcpd: Internet Systems Consortium DHCP Server 4.1.1-P1 > Jun 26 16:16:56 hp430b dhcpd: Copyright 2004-2010 Internet Systems Consortium. > Jun 26 16:16:56 hp430b dhcpd: All rights reserved. > Jun 26 16:16:56 hp430b dhcpd: For info, please visit https://www.isc.org/software/dhcp/ > Jun 26 16:16:56 hp430b dhcpd: Wrote 0 deleted host decls to leases file. > Jun 26 16:16:56 hp430b dhcpd: Wrote 0 new dynamic host decls to leases file. > Jun 26 16:16:56 hp430b dhcpd: Wrote 0 leases to leases file. > Jun 26 16:16:56 hp430b dhcpd: Listening on LPF/wlan0/68:a3:c4:b9:e0:64/192.168.0.0/24 > Jun 26 16:16:56 hp430b dhcpd: Sending on LPF/wlan0/68:a3:c4:b9:e0:64/192.168.0.0/24 > Jun 26 16:16:56 hp430b dhcpd: Listening on LPF/eth0/9c:8e:99:37:f1:54/192.168.5.0/24 > Jun 26 16:16:56 hp430b dhcpd: Sending on LPF/eth0/9c:8e:99:37:f1:54/192.168.5.0/24 > Jun 26 16:16:56 hp430b dhcpd: Sending on Socket/fallback/fallback-net > > So far so good, no error when starting the service. > > * configured router so that wlan0 always gets 192.168.0.103 > * configured so that eth0 gets fixed IP 192.168.5.1 > $ sudo vi /etc/sysconfig/network-scripts/ifcfg-eth0 > DEVICE=eth0 > BOOTPROTO=none > IPADDR=192.168.5.1 > NETMASK=255.255.255.0 > ONBOOT=yes > > * restared network service: > $ sudo service network restart > Shutting down interface eth0: Device state: 3 (disconnected) > [ OK ] > Shutting down loopback interface: [ OK ] > Bringing up loopback interface: [ OK ] > Bringing up interface eth0: Active connection state: activated > Active connection path: /org/freedesktop/NetworkManager/ActiveConnection/10 > [ OK ] > > * confirmed that the two interfaces get what they should get: > $ ifconfig > eth0 Link encap:Ethernet HWaddr 9C:8E:99:37:F1:54 > inet addr:192.168.5.1 Bcast:192.168.5.255 Mask:255.255.255.0 > inet6 addr: fe80::9e8e:99ff:fe37:f154/64 Scope:Link > UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 > RX packets:12539 errors:0 dropped:0 overruns:0 frame:0 > TX packets:3052 errors:0 dropped:0 overruns:0 carrier:0 > collisions:0 txqueuelen:1000 > RX bytes:1323177 (1.2 MiB) TX bytes:340948 (332.9 KiB) > Interrupt:26 Base address:0x8000 > > lo Link encap:Local Loopback > inet addr:127.0.0.1 Mask:255.0.0.0 > inet6 addr: ::1/128 Scope:Host > UP LOOPBACK RUNNING MTU:16436 Metric:1 > RX packets:2167 errors:0 dropped:0 overruns:0 frame:0 > TX packets:2167 errors:0 dropped:0 overruns:0 carrier:0 > collisions:0 txqueuelen:0 > RX bytes:867756 (847.4 KiB) TX bytes:867756 (847.4 KiB) > > wlan0 Link encap:Ethernet HWaddr 68:A3:C4:B9:E0:64 > inet addr:192.168.0.103 Bcast:192.168.0.255 Mask:255.255.255.0 > inet6 addr: fe80::6aa3:c4ff:feb9:e064/64 Scope:Link > UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 > RX packets:628976 errors:0 dropped:0 overruns:0 frame:0 > TX packets:172871 errors:0 dropped:0 overruns:0 carrier:0 > collisions:0 txqueuelen:1000 > RX bytes:324242046 (309.2 MiB) TX bytes:22038298 (21.0 MiB) > > * configured iptables to do the IP masquerading > $ sudo iptables -A FORWARD -i eth0 -o wlan0 -m state --state ESTABLISHED,RELATED -j ACCEPT > $ sudo iptables -A FORWARD -i wlan0 -o eth0 -j ACCEPT > $ sudo iptables -t nat -A POSTROUTING -o eth0 -j SNAT --to 117.4.113.206 > $ sudo iptables -t nat -A POSTROUTING -o eth0 -j MASQUERAGE > > Finally, I use another computer to be a client on 192.168.5 network, tried to give it IP for example 192.168.5.2, gateway 192.168.5.1 but I cant go to the internet. I can only see the DHCP server (by ping or ssh to 192.168.5.1). > > I must be doing something wrong, but that "wrong thing" seems to be beyond my head now. Any advice/suggestion is welcome!!! > > Thanks,