This section describes what is needed for the authentication gateway.
The authentication gateway uses Netfilter and iptables to manage the firewall. Please see the Netfilter HOWTO .
One means to insert and remove Netfilter rules is to use pam_iptables. This is a pluggable authentication module (PAM) written by Nathan Zorn that can be found at http://www.itlab.musc.edu/~nathan/pam_iptables . This PAM module allows users to use ssh and telnet to authenticate to the gateway.
Another means to dynamically remove and create Netfilter rules is to use NocatAuth. NocatAuth can be found at http://nocat.net . NocatAuth provides a web client for authenticating to the gateway.
The authentication gateway will act as the dynamic host configuration protocol (DHCP) server for the public network. It only serves those requesting DHCP services on the public network. I used the ISC DHCP Server .
The gateway can use any means of PAM authentication. The authentication mechanism the Medical University of South Carolina uses is LDAP. Since LDAP was used for authentication, the pam modules on the gateway box were set up to use LDAP. More information can be found at http://www.padl.com/pam_ldap.html . PAM allows you to use many means of authentication. Please see the documentation for the PAM module you would like to use. For more information on other methods, see pam modules .
If NocatAuth is used, an authentication service needs to be setup. The NocatAuth authentication service supports authentication with LDAP,RADIUS,MySQL,and a password file. More information can be found at http://nocat.net/download/NoCatAuth/ .
The gateway box also serves as a DNS server for the public network. I installed Bind, and set it up as a caching nameserver. The rpm package caching-namserver was also used. This package came with Red Hat.