Designing and Implementing Linux Firewalls with QoS using netfilter, iproute2, NAT and L7-filter
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This practical guide teaches you how to implement effective network protection by using your own customized firewall solution. Based on extensive practical experience, this book distills a unique set of scenario based scripts and guidelines for a proven firewall solution, into one succinct and precise book. This book is aimed at Linux Network administrators with some understanding of Linux security threats and issues, or any one interested in securing their systems behind a firewall. Basic knowledge of Linux is presumed but other than that this book shows you how to do the rest, from configuring your system to dealing with security breaches.
RARP associates a known MAC address to an IP address. A RARP server must be configured with the MAC addresses of the stations using RARP and IP addresses for those stations. Please note that MAC addresses are Layer 2 addresses that make sense only in the local network. Routers will not forward these outside the LAN. IP Classes An IP address has two parts: one that specifies the network that it is in, and one that uniquely identifies it in that network. The first part is called the network
network the DMZ zone . • The executive department network contains the computers for all the managers in the company. They expressed their need to have the least restriction possible for special chat applications and so on (and also file sharing). We assign a 32-hosts subnet from our class C for them, the 126.96.36.199/27 network. We assign the static public IP address 188.8.131.52, netmask 255.255.255.224 on Eth2 of our Linux router, and statically assign to them IP addresses from 184.108.40.206 to
site A, and we can either change the port on which MSSQL is running, or we can give the developers another port and can DNAT that port to 1433/TCP. In our example, we will leave MSSQL running on 1433/TCP and we will give the developers port 9001/TCP to connect to the MSSQL server in site A, which we will then DNAT to 1433/TCP. Another complicated situation has to do with the IP Analog Telephone Adapters (ATA). They use the protocol H.323, which is not so NAT-friendly, because it uses UDP to
received. If packets get lost along the way, this will force the sending host to resend that packet, thus ensuring a reliable communication. [ 17 ] Networking Fundamentals Please note that TCP is a connection-oriented protocol with reliable data transmission and flow control. Applications with the need of reliable data transmission use TCP as transport protocol. Examples of such applications are FTP, HTTP, SMTP, Telnet, SSH, etc. The User Datagram Protocol (UDP) UDP is a much simpler
peering connections. There are high-speed links between them, and routes are distributed between them for better load balancing of internet and peering connections. The distribution layer contains routers that route several customers in different locations, while the access layer contains routers at the customer premises, which can even be SOHO routers for smaller customers. Of course you can have customers connected directly to a core router, which means that the core router also performs