Red Hat Certified Engineer Tutorials
Network Configuration and Security / Network Access Translation (NAT)
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Subtitles of the Movie (Red Hat Certified Engineer / Network Configuration and Security / Network Access Translation (NAT))
The iptables command also works for network address translation. The most common form of which is known as Masquerading. This alters the source ip address of data packets that travel through an associated Firewall. As of this writing, network address translation does not work for IPv6 addressing, so what we discuss here applies solely to IPv4 networks. It's most commonly used at the junction between a LAN configured with a private ip network address, and the connection to an outside network such as the Internet, with a public ip address. In other words, it's used at the Gateway. While it uses the same ip tables command associated with Firewalls and is designed to work with data traveling through a Gateway, the functionality of a network address translation, or NAT, Masquerade is different. As it hides ip addresses it protects systems inside the local network behind the Firewall. When private ip networks are used they're often used behind a public ip address on a Gateway router, thus the address substitution associated with Masquerading gives requests to public networks, such as the Internet, the face of a public ip address. A typical Masquerading iptables command looks like the following: the dash t NAT specifies network address translation. The dash A POSTROUTING label appends and allows the altering of the ip address as it leaves the router through the network device as defined by dash o output eth0, the first Ethernet card. Substitute accordingly if you have a different outgoing network device. The j Masquerade jumps to Masquerade the packet with the ip address. In this case, the address assigned to network card eth0. When packets leave the Masquerade Gateway, those packets are tabled. When a response is heard, that table is used to restore the original ip address and the answer is sent back to your private LAN to the appropriate system. Once you set up the Masquerade don't forget to save the new rule. As described in another video, any rule you make with the iptables command can be saved in the etc slash sysconf slash iptables file with the etc slash init dot d slash iptables save command.
Tutorial Information
| Course: | Red Hat Certified Engineer |
| Author: | Michael Jang |
| SKU: | 33845 |
| ISBN: | 1-934743-47-X |
| Release Date: | 2008-01-18 |
| Duration: | 6.5 hrs / 94 lessons |
| Captions: | No |
| Compatibility: |
Vista/XP/2000, OS X, Linux QuickTime 7, Flash 8 |
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