NAT Principle Introduction, Various ADSL MODEM and Port Mappings of Routers
NAT principle profile
NAT English is "NetWork Address Translation", meaning "Network Address Translation", which is a standard of IETF (Internet Engineering Task Force, Internet Engineering Task Group), allowing an overall mechanism to appear in an integral IP (Internet Protocol) address On the Internet. As the name suggests, it is a technology that translates internal private network addresses (IP addresses) into legitimate network IP addresses. Figure:
Simply put, NAT uses internal addresses in the network internal network, and when the internal node is communicating with external network, it will be in the gateway (it can be understood as an exit, and it is like a door to the yard). The address replaces the public address, thereby using normal use on the Internet, NAT can share multiple computers sharing Internet connection, which is well solved the problem of the short IP address. In this way, you can only apply for an legitimate IP address, connect the computer in the entire LAN to the Internet. At this time, NAT blocks the internal network, and all internal network computers are invisible for public networks, while internal network computer users usually will not recognize the presence of NAT. as shown in picture 2. The internal address mentioned here refers to the private IP address assigned to the node in the internal network. This address can only be used in the internal network, and different path forwardings can be implemented in the internal network (a network technology). Although internal addresses can be randomly selected, the following address is usually used: 10.0.0.0 ~ 10.255.255.255, 172.16.0.0 ~ 172.16.255.255, 192.168.0.0 ~ 192.168.255.255. NAT translates these ip addresses that cannot be used on the Internet into legitimate IP addresses that can be used on the Internet. The global address refers to the legal IP address, which is an address assigned by the NIC (Network Information Center) or ISP (Network Service Provider), which represents one or more internal local addresses, is a global unified addressable address.
NAT features are typically integrated into routers, firewalls, ISDN routers, or separate NAT devices. For example, this feature has been added in the Cisco router, and the network administrator only needs to set a NAT function in the IOS of the router, you can implement the mask of the internal network. For example, the firewall maps the internal address 192.168.168.1.1.168.1.1 of Web Server to external addresses 202.96.23.11, external access 202.96.23.11 The address is actually an access to access 192.168.1.1. In addition, small companies with limited funds, this feature can now be achieved by software. Windows 98 SE, Windows 2000 contains this feature.
NAT technology type
NAT has three types: static NAT (static NAT), dynamic address NAT (Pooled NAT), network address port conversion NAPT (port-level nat).
One of the most simple and easier implementations of static NAT are set, each host in the internal network is permanently mapped into an legal address in the external network. The dynamic address NAT is a series of legitimate addresses that define a series of legitimate addresses in the external network. Maps are mapped to the internal network. NAPT is on different ports that map the internal address to an IP address of the external network. According to different needs, the three NAT programs have their own advantages and disadvantages.
Dynamic address NAT is only converted to the IP address, which assigns a temporary external IP address for each internal IP address, mainly to dialing, and dynamic NAT can also be used for frequent remote coupling. When the remote user is connected, the dynamic address NAT will assign him an IP address. When the user is disconnected, this IP address will be released and left later. Network Address Port Conversion Napt (Network Address Port Translation) is a more familiar way. NAPT is generally applied to access devices, which can hide the small and medium-sized network behind a legitimate IP address. NAPT is different from the dynamic address NAT, which maps the internal connection to a separate IP address in the external network while adding a TCP port number selected by the NAT device. When using NAPT in the Internet, all different information flows seem to be derived from the same IP address. This advantage is very practical in the small office. By accessing multiple connections through NAPT access Internet by an IP address applied by the ISP. In fact, many SOHO remote access devices support PPP-based dynamic IP addresses. In this way, ISP does not even need to support NAPT, you can do multiple internal IP addresses to share an external IP address, although this will lead to a certain congestion of the channel, but considering the savings of ISP Internet fees and easy management features, NAPT is still worth it.
ADSL MODEM port mapping explanation
If the ADSL itself has a routing function, you need to set the appropriate port mapping in the "Management Interface" of ADSL. The way the settings may vary because of the different brands and models of ADSL, will also vary in the way. We collect and summarize some ways of port mapping of common ADSL, please set the relevant model. If the ADSL cat you use is not within the scope of our summary, please pm to us, we will find a way to add it as soon as possible.
Dasa Technology _adsl_db108 and DB102 port mapping setting (by: kevinxp919) ZHAD _ADSL_2110EH port mapping setting (BY: Sweet waves) 天邑 _adsl_haASB-100 port mapping settings (by: mmmxxx) ztx ZTE _adsl_831 port Mapping setting (by: mmmxxx) Itek (E.TEK.TD) _ADSL_TD-2018 port mapping setting (by: mmmxxx) Alcatera _ADSL_MODEM511E port mapping setting (BY: KOKKIBOY) ASUS_ADSL_AAM6000EV port mapping setting (BY: OUSHIDAXIONG) The setting of Huawei _ADSL_MT800 port mapping (by: mmmxxx) Putian _ADSL_GS8100 port mapping setting (by: chilka) Digital _adsl_dcad-6010ra port map setting (BY: ZWKERE) (11) Greennet_adsl_1500c port mapping settings ( By: CRYPTO)
Router's port mapping explanation
If you are online through the ADSL router, you need to make a corresponding port mapping in the router. The method of setting may vary because of the different brands and models of the router, there will be differences on the settings. We collect and summarize the methods of some common ADSL port mappings, please set it with reference to the relevant model. If the router you are using is not within the scope of our summary, please pm to us, we will find a way to add it as soon as possible. Zhongyi Wide SerCOMM IP505 (LT / LM / T) Series Router Port Mapping Settings (BY: MMMXXX) D-Link DSL-500 Broadband Router Port Mapping setting (BY: MoxNet) TP-LINK R460 router port mapping settings (By: mmmxxx) TP-LINK TD8830 router port mapping setting (BY: XNQY Repost) Linksys Series Router Port Mapping setting (by: mmmxxx)
