经常需要在linux/freebsd下查看进程监听的端口，或知道端口，查找其绑定的进程。这就需要一些工具。

linux

netstat，ss，lsof都能实现，首选ss，其次是lsof。

rui@xu4322830 /o/nfs_root> sudo netstat -tulpn | grep :179
tcp 0 0 0.0.0.0:179 0.0.0.0:* LISTEN 3924/bird
rui@xu4322830 /o/nfs_root> sudo netstat -tulpn | grep 22
tcp6 0 0 :::22 :::* LISTEN 1/init
udp6 0 0 :::40227 :::* 15953/rpc.statd
rui@xu4322830 /o/nfs_root> sudo ss -tulpn | grep 22
udp UNCONN 0 0 [::]:40227 [::]:* users:(("rpc.statd",pid=15953,fd=10))
tcp LISTEN 0 4096 *:22 *:* users:(("systemd",pid=1,fd=53))

奇怪的是，netstat显示不出ssh ipv4的端口，netstat已经被认为是遗弃状态，建议用ss。

lsof适合于知道端口的情况下，查看连接

rui@xu4322830 /o/nfs_root> sudo lsof -i -P | grep :22
systemd 1 root 53u IPv6 13230 0t0 TCP *:22 (LISTEN)
systemd 1 root 77u IPv6 2844831 0t0 TCP xu4322830:22->137.184.233.98:34816 (ESTABLISHED)
sshd 25638 root 3u IPv6 2844831 0t0 TCP xu4322830:22->137.184.233.98:34816 (ESTABLISHED)
sshd 25638 root 4u IPv6 2844831 0t0 TCP xu4322830:22->137.184.233.98:34816 (ESTABLISHED)
sshd 25641 sshd 3u IPv6 2844831 0t0 TCP xu4322830:22->137.184.233.98:34816 (ESTABLISHED)
sshd 25641 sshd 4u IPv6 2844831 0t0 TCP xu4322830:22->137.184.233.98:34816 (ESTABLISHED)

对于kernel module来说，目前还没有一个工具能查看其所监听的端口。因为它不是一个进程。而netstsat、ss、lsof都是从/proc来获取信息。

参考：

https://www.reddit.com/r/linuxadmin/comments/12y4loy/finding_kernel_modules_using_listening_sockets/

freebsd

sockstat可以查看某个端口的监听进程

rui@fbn54l /etc> doas sockstat -4 -l
USER COMMAND PID FD PROTO LOCAL ADDRESS FOREIGN ADDRESS
root mountd 8755 8 udp4 *:748 *:*
root mountd 8755 9 tcp4 *:748 *:*
root nfsd 8472 5 tcp4 *:2049 *:*
root rpcbind 8439 9 udp4 *:111 *:*
root rpcbind 8439 10 udp4 *:886 *:*
root rpcbind 8439 11 tcp4 *:111 *:*
root inetd 1281 6 udp4 *:69 *:*
root sshd 1274 4 tcp4 *:22 *:*
root sendmail 1242 5 tcp4 127.0.0.1:25 *:*
chronyd chronyd 790 6 udp4 *:123 *:*
root syslogd 722 7 udp4 *:514 *:*
? ? ? ? udp4 *:2049 *:*
sockstat -4 -l | grep :2049
root nfsd 8472 5 tcp4 *:2049 *:*
? ? ? ? udp4 *:2049 *:*

netstat&lsof也能查看，多了一步。

rui@fbn54l /etc> doas netstat -a | egrep 'LISTEN'
tcp4 0 0 *.ris-cm *.* LISTEN
tcp6 0 0 *.ris-cm *.* LISTEN
tcp6 0 0 *.nfsd *.* LISTEN
tcp4 0 0 *.nfsd *.* LISTEN
tcp4 0 0 *.sunrpc *.* LISTEN
tcp6 0 0 *.sunrpc *.* LISTEN
tcp4 0 0 *.ssh *.* LISTEN
tcp6 0 0 *.ssh *.* LISTEN
tcp4 0 0 localhost.smtp *.* LISTEN
rui@fbn54l /etc> doas netstat -a -n | egrep 'LISTEN'
tcp4 0 0 *.748 *.* LISTEN
tcp6 0 0 *.748 *.* LISTEN
tcp6 0 0 *.2049 *.* LISTEN
tcp4 0 0 *.2049 *.* LISTEN
tcp4 0 0 *.111 *.* LISTEN
tcp6 0 0 *.111 *.* LISTEN
tcp4 0 0 *.22 *.* LISTEN
tcp6 0 0 *.22 *.* LISTEN
tcp4 0 0 127.0.0.1.25 *.* LISTEN
rui@fbn54l /etc> doas lsof -i :2049
lsof: WARNING: compiled for FreeBSD release 13.1-RELEASE-p5; this is 13.1-RELEASE-p6.
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
nfsd 8472 root 5u IPv4 0xfffffe00d165d000 0t0 TCP *:nfsd (LISTEN)
nfsd 8472 root 6u IPv6 0xfffffe00d15f9870 0t0 TCP *:nfsd (LISTEN)