Authors Michael Shinn and Scott Shinn are among the world's leading firewall experts; they've even been hired to protect computer security at the White House. In this book, they cover every area where Linux firewalls can go wrong: rules and filtering problems, Layer 2/3/4 issues, trouble with individual services, DNS/DHCP failures, even misconfigured VPNs. They also present an easy, start-to-finish troubleshooting methodology that'll help you identify even the newest or most obscure firewall problem fast-and solve it!Inside, you will find in-depth information on the following areas: * What you must know about iptables and netfilter to troubleshoot and avoid problems * Using loggers, sniffers, and other tools to diagnose even the most obscure firewall problems * Making sure your firewall rules work the way they're supposed to * Resolving problems with Network Address Translation and IP Forwarding * Troubleshooting SMTP, Apache, Squid, NFS, FTP, instant messaging, and other Web-based services * Finding and fixing common problems with IPsec VPN configuration * Making your firewalls more failure-resistant: recommendations from the expertsIf you depend on a Linux firewall, what will you do if it goes down? With Troubleshooting LinuxR Firewalls, you can be confident that the solutions are right at hand-so you can sleep at night!"