我在 Debian Buster 上安裝了 unbound。現在我想知道為什麼 unbound 在每個協議上監聽 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
誰能幫助我理解這一點?
答案1
無界使用SO_REUSEPORT允許多個/進程執行緒共享相同偵聽連接埠的選項。
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.