在Linux上，如何在不尝试连接的情况下检查端口是否处于侦听状态

如何用C检查本地计算机上的端口(如果也需要通过传递IP或接口来实现)是否处于侦听状态?我不想连接到该端口进行检查，因为我不想激怒该端口后面的服务.

How do I check with C if a port on my local machine (if required by passing an IP or interface, too), is in listen state? I don't want to connect to this port for checking because I don't want to irritate the service behind this port.

我想用它来将缺少的net.tcp.listen项目添加到Zabbix.

I want to use this to add the missing net.tcp.listen item to Zabbix.

编辑-这是真正的答案:

EDIT - THIS IS THE REAL ANSWER:

正确的方法是读取套接字表:

The correct way is to read the socket tables:

/proc/net/tcp /proc/net/tcp6

/proc/net/tcp /proc/net/tcp6

它们包含如下行:

sl  local_address rem_address   st tx_queue rx_queue tr tm->when retrnsmt   uid  timeout inode
0: 00000000:1F40 00000000:0000 0A 00000000:00000000 00:00000000 00000000   101        0 4083927 1 f5d15240 750 0 0 2 -1
1: 00000000:2742 00000000:0000 0A 00000000:00000000 00:00000000 00000000  1002        0 6100 1 decd76c0 750 0 0 2 -1

，并且可以轻松地解析侦听套接字(dst:00000000:0000). netstat上的strace显示netstat的工作方式相同.

and can easily parsed for listening sockets (dst:00000000:0000). An strace on netstat shows that netstat works the same way.