The role of the router

Routers (Router) are one of the most important devices on the Internet, and it is the tens of thousands of routers all over the world that make up the internet, the "bridge" of the giant information network that is running around the clock. The core communication mechanism of Internet is a data transmission model called "store and Forward". Under this communication mechanism, all data flowing over the network is sent, transmitted and received in the form of a packet (Packet). Any computer that accesses the Internet must have a unique network "address" to communicate with other machines and exchange information.

The data is not transmitted directly from its "starting point" to "destination", and instead, the data is divided into segments of a certain length--packets--according to specific criteria before transmission. Each packet is added to the destination computer's network address, which is like a set of envelopes to write a good recipient address, such packets will not "stray" when transmitted online. These packets must be forwarded and relayed through a large number of communication devices or computers on the internet before they reach their destination. The operation of the ancient post station is an image metaphor of this process, on the Internet, the router is playing the forwarding packet "post" role.

Most popular routers are in the form of hardware devices, but in some cases the software router is implemented using a program, the only difference is the efficiency of the execution. Routers are generally associated with at least two networks and determine the transmission path of each packet based on the state of the network to which it is connected. The router generates and maintains a table called the Routing information table, which tracks the address and status information of other neighboring routers. Routers use the Routing information table and determine the optimal transmission path for a particular packet based on optimization algorithms such as transmission distance and communication cost. It is this characteristic that determines the "intelligence" of the router, it can automatically select and adjust the transmission of the packet according to the actual running condition of the neighboring network, and make the best effort to pass the packet through the best route and the lowest cost. Whether the router can operate safely and stably affects the activity of the Internet directly. Whatever the reason for the crash of a router, denial of service, or a sharp decline in operational efficiency, the result will be catastrophic.

Hackers attack routers in much the same way as attacking other computers on the Internet, because the router itself is a computer with a special mission in its own right, though it may not look like a PC that people usually know. Generally speaking, the hacker attacks on the router mainly divided into the following two types: first, through some means or ways to obtain administrative authority, direct intrusion into the internal system; First, the use of remote attacks caused by the crash of the router or the operation efficiency significantly decreased. In comparison, the former is more difficult.

In the first intrusion method mentioned above, hackers generally take advantage of the careless or known system flaws of the system's users (such as "bugs" in the system software) to gain access to the system, and ultimately gain Super Administrator privileges through a series of further actions. It is generally difficult for hackers to gain control of the entire system from the outset, which is a gradual escalation of the intrusion process in general. Because routers do not have a large number of user accounts like a typical system, and often use proprietary software systems with relatively high security, it will be much more difficult for hackers to gain the right to manage a router system than to invade a general host. Therefore, most of the existing hacker attacks on routers can be categorized into the category of the second type of attack. The ultimate goal of such an attack is not to invade the system directly, but to send an aggressive packet to the system or, at a certain time interval, to send a huge amount of "garbage" packets to the system, which consumes the router's system resources so much that it does not work properly or even crashes completely.

Routing Technology Introduction

Stun Technology:

Serial tunneling (serial tunnel) technology. The technology is to send the SNA packages from the FEP (3745/6) serial port to the router, the router is packaged into an IP packet and then transferred to the SDLC interface device after the router is routed to the target router and then SDLC to the SNA.

CIP technology: CIP-Channel Interface processor (Channel Interface Processor). It is made into a card device that can be conveniently installed in the CISCO7000 series of routers. CIP provides a multi-protocol network access capability for IBM mainframe by connecting directly to IBM mainframe. Provides TCP/IP, SNA, and APPN traffic for large machines, eliminating the need for intermediate devices such as 3172 interconnection controllers and Ibm3745/6 FEP.

DLSW Technology:

is a kind of international standard technology, the software package of SNA can be packaged by IP to transmit to any router node of IP network, then the serial port of the router is transmitted to SDLC interface device or via Ethernet interface (or Token Ring) by SDLC way. Interface devices are transmitted to the SNA nodes (such as RS6000) that transmit SNA packets to the LLC2 link layer protocol.

A E1 interface for MIP:

can provide 30 64Kbps of sub channels, the channel can also be combined into a larger nx64k channel, sufficient for a considerable amount of time with the city line of the bandwidth requirements of the connection. Ciscoworks: NMS is a series of SNMP based management applications that can be integrated on Sunnet Manager, HP OpenView, IBM Netview/aix, windows95/nt platform, The main features offered include the ability to remotely install new routers from neighboring routers to provide extensive dynamic state, statistics, and configuration information to Cisco's Internet products, visually graphically display Cisco's devices, and basic troubleshooting information.

Audit and record configuration file changes, detects unauthorized configuration changes on the network to facilitate the configuration of similar routers in the network to record the details of a contact for a particular device view the status information of a device, including buffer memory, CPU load, available memory, the interface being used and the protocol collecting history data of the network.

Analyze network traffic and performance trends and graphically display the authorization checker to protect Ciscoworks applications and network devices from unauthorized users. It is particularly important to note that Cisco provides a good management of the SNA Internet, Specially developed for IBM Network management Ciscoworks Blue Management application, in addition to supporting the above functions, but also to increase the mibs of the SNA in the router, Support NMVT and LU6.2 Management, provide SNA management related functions, such as: Know the status of each SNA resources in the network, and use to change the SNA resource status to help detect the delay of network data flow, can be used to measure the response time from the host to Lu.