![了解 Unbound 如何监听 53 端口](https://linux22.com/image/776840/%E4%BA%86%E8%A7%A3%20Unbound%20%E5%A6%82%E4%BD%95%E7%9B%91%E5%90%AC%2053%20%E7%AB%AF%E5%8F%A3.png)
我在 Debian Buster 上安装了 unbound。现在我想知道为什么 unbound 在每个协议上监听 2 次。
netstat -tulpn
tcp 0 0 0.0.0.0:53 0.0.0.0:* LISTEN 1150/unbound
tcp 0 0 0.0.0.0:53 0.0.0.0:* LISTEN 1150/unbound
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 605/sshd: /usr/sbin
tcp 0 0 127.0.0.1:8953 0.0.0.0:* LISTEN 1150/unbound
tcp6 0 0 :::22 :::* LISTEN 605/sshd: /usr/sbin
udp 0 0 0.0.0.0:53 0.0.0.0:* 1150/unbound
udp 0 0 0.0.0.0:53 0.0.0.0:* 1150/unbound
有人能帮助我理解这一点吗?
答案1
Unbound 使用重用端口允许多个进程线程共享同一个监听端口的选项。
Permits multiple AF_INET or AF_INET6 sockets to be bound
to an identical socket address. This option must be set
on each socket (including the first socket) prior to
calling bind(2) on the socket. To prevent port hijacking,
all of the processes binding to the same address must have
the same effective UID. This option can be employed with
both TCP and UDP sockets.
For TCP sockets, this option allows accept(2) load
distribution in a multi-threaded server to be improved by
using a distinct listener socket for each thread. This
provides improved load distribution as compared to
traditional techniques such using a single accept(2)ing
thread that distributes connections, or having multiple
threads that compete to accept(2) from the same socket.
For UDP sockets, the use of this option can provide better
distribution of incoming datagrams to multiple processes
(or threads) as compared to the traditional technique of
having multiple processes compete to receive datagrams on
the same socket.