Shulou(Shulou.com)06/03 Report--

What is TraceRoute? In response to this problem, this article introduces the corresponding analysis and solution in detail, hoping to help more small partners who want to solve this problem find a simpler and easier way.

The TraceRoute command uses ICMP protocol to locate all routers between your computer and the destination computer, where TTL values reflect the number of routers or gateways through which packets pass, by manipulating TTL values for individual ICMP call messages and observing the message being discarded back.

TraceRoute Principle

The simplest basic usage of Traceroute is: traceroute hostname

Traceroute programs are designed to use ICMP and TTL (Time To Live) fields in IP headers. First, traceroute sends an IP datagram with TTL 1 (in fact, three 40-byte packets are sent at a time, including the source address, destination address, and packet origin time tag) to the destination, and when the first router on the path receives the datagram, it subtracts TTL by 1. At this point, TTL becomes 0, so the router will drop this datagram and send back an "ICMP time exceeded" message (including the source address of the IP packet, all the contents of the IP packet and the IP address of the router). After traceroute receives this message, it knows that this router exists on this path. Then traceroute sends another datagram with TTL 2 and finds the second router. Traceroute adds 1 to the TTL of each datagram sent to discover another router, and this repeated action continues until a datagram arrives at its destination. When the datagram arrives at the destination, the host does not send back ICMP time exceeded messages because it is already the destination, so how does traceroute know that the destination has arrived?

When Traceroute sends UDP datagrams to the destination, the port number it chooses to send is a number (above 30000) that is not used by ordinary applications, so when the UDP datagram arrives at the destination, the host will send back an "ICMP port unreachable" message, and when traceroute receives this message, it knows that the destination has arrived. So traceroute on the Server side is also no so-called Daemon program.

Traceroute extracts the IP address of the device that sent the ICMP TTL expiration message and performs domain name resolution. Each time Traceroute prints out a series of data including the domain names and IP addresses of the routing devices it passes through, three times how long it takes for the packet to go back and forth.

Traceroute has a fixed time to wait for a response (ICMP TTL expiration message). If this time elapses, it prints a series of * marks indicating that the device on this path cannot respond to ICMP TTL expiration messages within the given time. Traceroute then adds 1 to the TTL counter and proceeds.

gateway

Traceroute(or Tracert) is generally based on a host, but usually you can only know the quality of the route connection and the efficiency of data transmission from the host at hand to any online host on the Internet, while using a web-based approach, as long as a host is installed with a specific CGI program, the user can run the relevant program through this host to perform Traceroute functions. This mainframe we call Traceroute Gateway. Traceroute gateway can help users understand the topology of physical and logical connections and the efficiency of data transmission. If there are enough gateways, we can easily understand the connection between the hosts.

function

Traceroute was first developed as Mini programs by Van Jacobson in 1988. At that time, it was mainly to solve some network problems he encountered. Traceroute is an important tool for understanding IP networks correctly and understanding routing principles. Webmaster, which they are responsible for network engineering technology and system administration, is a handy program.

For ISPs, the Traceroute Gateway will enable ISPs to help customers build and maintain confidence in the quality of service provided by their service providers. ISPs with high quality of service can set up Traceroute gateways to let users know how efficiently they connect to the network and transmit data. Of course, ISPs with poor infrastructure and low quality of service are more afraid to provide this service. This way, users can use this tool to understand the network connection of service providers.

After a host has been installed with the relevant Traceroute CGI program, you can enter the IP address or name of the corresponding destination host and get the relevant data.

About TraceRoute is what the answer to the question is shared here, I hope the above content can be of some help to everyone, if you still have a lot of doubts not solved, you can pay attention to the industry information channel to learn more related knowledge.

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