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Paping (pronounced pah ping) is a computer network administration utility used to test the reachability of a host on an Internet Protocol (TCP/IP) network and to measure the time it takes to connect to a specified port. The name is a play on the word ping, another computer network administration utility. Because ICMP can be used to identify the ...
In computer networking, port knocking is a method of externally opening ports on a firewall by generating a connection attempt on a set of prespecified closed ports. Once a correct sequence of connection attempts is received, the firewall rules are dynamically modified to allow the host which sent the connection attempts to connect over specific port(s).
A Docker container is a standardized, encapsulated environment that runs applications. [25] A container is managed using the Docker API or CLI. [22] A Docker image is a read-only template used to build containers. Images are used to store and ship applications. [22] A Docker service allows containers to be scaled across multiple Docker daemons.
An ephemeral port is a communications endpoint of a transport layer protocol of the Internet protocol suite that is used for only a short period of time for the duration of a communication session. Such short-lived ports are allocated automatically within a predefined range of port numbers by the IP stack software of a computer operating system.
The port numbers in the range from 0 to 1023 (0 to 2 10 − 1) are the well-known ports or system ports. [3] They are used by system processes that provide widely used types of network services. On Unix-like operating systems, a process must execute with superuser privileges to be able to bind a network socket to an IP address using one of the ...
[e] Registered ports are typically used by end-user applications as ephemeral source ports when contacting servers, but they can also identify named services that have been registered by a third party. Dynamic or private ports can also be used by end-user applications, however, these ports typically do not contain any meaning outside a ...
Cisco's implementation of traceroute also uses a sequence of UDP datagrams, each with incrementing TTL values, to an invalid port number at the remote host; by default, UDP port 33434 is used. An extended version of this command (known as the extended traceroute command) can change the destination port number used by the UDP probe messages. [13]
The ICMP header starts after the IPv4 header and is identified by its protocol number, 1. [6] All ICMP packets have an eight-byte header and variable-sized data section. The first four bytes of the header have fixed format, while the last four bytes depend on the type and code of the ICMP packet.