Hi anorman,
Congratulations! You are already in the middle of the journey. To configure gateway and dnsservers you have to change you dhcpd.conf, including or editing this three lines in the global configuration:
Code:
option routers 192.168.2.1;
option domain-name-servers xx.xx.xx.xx;
option domain-name "your-domain";
Ok, on the xx.xx.xx.xx you may use the dns servers provided by your ISP and, in this case, your domain will also be the domain of your ISP. However, when your internet connection is down, any station will slow to death when trying to resolve a new address. So, I suggest you install a local dns server. The official and default dns server for *nix and linux is bind. But it is difficult to configure and is not tailored for a connection like ours. It is conceived for a computer always connected and with fixed IP. So i recommend you install dnsmasq, which you can get at freshmeat. It has an easy configuration file and it stays alert to changes in environment like connection restart and turn on/off of your stations by looking to the leases of your dhcp server. In this case, you have to give in dhcpd.conf your machine as dns server and any name you like as your domain. Don't use the standard names such as .com, .net, etc. but, for example, .nor, .ano, .nrm. This server will resolve the addresses into your home network and, when it could not resolve, it will forward it to you ISP.
Now, we need to configure your server to forward the messages in and out your network. You have to configure a firewall to route the messages and masquerade you home ips. More than this we need to block the attacks you are constantly suffering. For this I suggest you visit
www.netfilter.org, with is the home of iptables, the framework developed to firewalling linux. There you will find deep information about this subject as well as scripts ready to do your job.
