Polyteknisk Boghandel

An Internet-connected Linux machine is in a high-risk situation. Linux Firewalls, Third Edition details security steps that any sized implementation--from home use to enterprise level--might take to protect itself from potential remote attackers. As with the first two editions, this book is especially useful for its explanations of iptables, packet filtering, and firewall optimization along with some advanced concepts including customizing the Linux kernel to enhance security.The third edition, while distribution neutral, has been updated for the current Linux Kernel and provides code examples for Red Hat, SUSE, and Debian implementations. Don't miss out on the third edition of the critically acclaimed Linux Firewalls.

Introduction. The Purpose of This Book. Who Should Read This Book. Linux Distribution. Errors in This Book. Companion Website.
I. PACKET-FILTERING AND BASIC SECURITY MEASURES.
1. Preliminary Concepts Underlying Packet-Filtering Firewalls. The OSI Networking Model. Connectionless Versus Connection-Oriented Protocols. Next Steps. The IP. IP Addressing and Subnetting. IP Fragmentation. Broadcasting and Multicasting. ICMP. Transport Mechanisms. UDP. TCP. Don't Forget ARP. Hostnames and IP Addresses. IP Addresses and Ethernet Addresses. Routing: Getting a Packet from Here to There. Service Ports: The Door to the Programs on Your System. A Typical TCP Connection: Visiting a Remote Website. Summary.
2. Packet-Filtering Concepts. A Packet-Filtering Firewall. Choosing a Default Packet-Filtering Policy. Rejecting Versus Denying a Packet. Filtering Incoming Packets. Remote Source Address Filtering. Local Destination Address Filtering. Remote Source Port Filtering. Local Destination Port Filtering. Incoming TCP Connection-State Filtering. Probes and Scans. Denial-of-Service Attacks. Source-Routed Packets. Filtering Outgoing Packets. Local Source Address Filtering. Remote Destination Address Filtering. Local Source Port Filtering. Remote Destination Port Filtering. Outgoing TCP Connection-State Filtering. Private Versus Public Network Services. Protecting Nonsecure Local Services. Selecting Services to Run. Summary.
3. iptables: The Linux Firewall Administration Program. Differences Between IPFW and Netfilter Firewall Mechanisms. IPFW Packet Traversal. Netfilter Packet Traversal. Basic iptables Syntax. iptables Features. NAT Table Features. mangle Table Features. iptables Syntax. filter Table Commands. filter Table Target Extensions. filter Table Match Extensions. NAT Table Target Extensions. mangle Table Commands. Summary.
4. Building and Installing a Standalone Firewall. iptables: The Linux Firewall Administration Program. Build Versus Buy: The Linux Kernel. Source and Destination Addressing Options. Initializing the Firewall. Symbolic Constants Used in the Firewall Examples. Enabling Kernel-Monitoring Support. Removing Any Preexisting Rules. Resetting Default Policies and Stopping the Firewall. Enabling the loopback Interface. Defining the Default Policy. Stealth Scans and TCP State Flags. Using Connection State to Bypass Rule Checking. Source Address Spoofing and Other Bad Addresses. Protecting Services on Assigned Unprivileged Ports. Common Local TCP Services Assigned to Unprivileged Ports. Common Local UDP Services Assigned to Unprivileged Ports. Enabling Basic, Required Internet Services. Allowing DNS (UDP/TCP Port 53). Filtering the AUTH User Identification Service (TCP Port 113). Enabling Common TCP Services. Email (TCP SMTP Port 25, POP Port 110, IMAP Port 143). Accessing Usenet News Services (TCP NNTP Port 119). Telnet (TCP Port 23). SSH (TCP Port 22). FTP (TCP Ports 21, 20). Web Services. Whois (TCP Port 43). RealAudio, RealVideo, and QuickTime (TCP Ports 554 and 7070). Enabling Common UDP Services. traceroute (UDP Port 33434). Accessing