View Extranet egress IP && Traceroute

I. CentOS View extranet egress IP

1----------------# Curl Ifconfig.me

2----------------# Curl Icanhazip.com

Two. The simplest basic usage of traceroute is: traceroute hostname

The Traceroute program is designed to utilize the TTL (Time to Live) field (field) of the ICMP and IP header. First, Traceroute sends out a TTL of 1 IP datagram (in fact, each sent out for 3 40-byte packets, including the source address, destination address and Packet issued time label) to the destination, when the path on the first router (router) received this datagram, It decrements the TTL by 1. At this point, the TTL becomes 0, so the router will discard 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), Traceroute received this message, Then know that this router exists on this path, then traceroute another TTL is 2 datagram, found the 2nd router ... traceroute each time the TTL of the datagram to be sent is added to discover another router, This repetitive action continues until a certain datagram arrives at the destination. When datagram arrives at the destination, the host does not send back the ICMP Time exceeded message because it is already a destination, so how does traceroute know where the destination has arrived?
When Traceroute sends out a UDP datagrams to its destination, the port number it chooses to deliver is one that is not used by a general application (30000 or more), so when this UDP datagram arrives at the destination, the host sends back an ICMP Port unreachable"the message, and when Traceroute receives the 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 ICMP TTL expiry message device and makes the domain name resolution. Each time, traceroute prints out a series of data, including the domain name and IP address of the routed device that was passed, and the time it takes each three packets to go back and forth.

View Extranet egress IP && Traceroute