{{ cat }}'s docs

内核参数: 1.1.3 内核listen()中的参数 backlog

listen man文档中的description: ''' listen() marks the socket referred to by sockfd as a passive socket, that is, as a socket that will be used to accept incoming connection requests using accept(2). The sockfd argument is a file descriptor that refers to a socket of type SOCK_STREAM or SOCK_SEQPACKET.

The backlog argument defines the maximum length to which the queue of pending connections for sockfd may grow. If a connection request arrives when the queue is full, the client may receive an error with an indication of ECONNREFUSED or, if the underlying protocol supports retransmission, the request may be ignored so that a later reattempt at connection succeeds. '''



ss -ln

State Recv-Q Send-Q Local Address:Port Peer Address:Port LISTEN 0 128 :::22 ::: LISTEN 0 128 :22 : LISTEN 0 100 ::1:25 ::: LISTEN 0 100 :*

ss 命令参数

-l, --listening Display listening sockets. -n, --numeric Do now try to resolve service names.


ss is used to dump socket statistics. It allows showing information similar to netstat. It can display more TCP and state informations than other tools.