想允许一个端口说 4000。跑：
root@66548e7316fc:/# sudo ufw allow 4000/tcp
WARN: initcaps
[Errno 2] iptables v1.6.1: can't initialize iptables table `filter': Permission denied (you must be root)
Perhaps iptables or your kernel needs to be upgraded.
Skipping adding existing rule
Skipping adding existing rule (v6)
root@66548e7316fc:/#
root@66548e7316fc:/# sudo ufw status
ERROR: problem running iptables: iptables v1.6.1: can't initialize iptables table `filter': Permission denied (you must be root)
Perhaps iptables or your kernel needs to be upgraded.
root@66548e7316fc:/# service ufw status
* Firewall is not running... [fail]
root@66548e7316fc:/# sudo ufw reload
Firewall not enabled (skipping reload)
root@94d82c9ba002:/# sudo ufw enable
ERROR: problem running ufw-init
/lib/ufw/ufw-init: 118: /lib/ufw/ufw-init: modprobe: not found
/lib/ufw/ufw-init: 118: /lib/ufw/ufw-init: modprobe: not found
/lib/ufw/ufw-init: 118: /lib/ufw/ufw-init: modprobe: not found
iptables-restore v1.6.1: iptables-restore: unable to initialize table 'filter'
Error occurred at line: 1
Try `iptables-restore -h' or 'iptables-restore --help' for more information.
iptables-restore v1.6.1: iptables-restore: unable to initialize table 'filter'
Error occurred at line: 1
Try `iptables-restore -h' or 'iptables-restore --help' for more information.
iptables-restore v1.6.1: iptables-restore: unable to initialize table 'filter'
Error occurred at line: 1
Try `iptables-restore -h' or 'iptables-restore --help' for more information.
iptables-restore v1.6.1: iptables-restore: unable to initialize table 'filter'
Error occurred at line: 1
Try `iptables-restore -h' or 'iptables-restore --help' for more information.
iptables-restore v1.6.1: iptables-restore: unable to initialize table 'filter'
Error occurred at line: 1
Try `iptables-restore -h' or 'iptables-restore --help' for more information.
iptables-restore v1.6.1: iptables-restore: unable to initialize table 'filter'
Error occurred at line: 12
Try `iptables-restore -h' or 'iptables-restore --help' for more information.
iptables-restore v1.6.1: iptables-restore: unable to initialize table 'filter'
Error occurred at line: 12
Try `iptables-restore -h' or 'iptables-restore --help' for more information.
iptables-restore v1.6.1: iptables-restore: unable to initialize table 'filter'
Error occurred at line: 1
Try `iptables-restore -h' or 'iptables-restore --help' for more information.
iptables-restore v1.6.1: iptables-restore: unable to initialize table 'filter'
Error occurred at line: 1
Try `iptables-restore -h' or 'iptables-restore --help' for more information.
iptables-restore v1.6.1: iptables-restore: unable to initialize table 'filter'
Error occurred at line: 1
Try `iptables-restore -h' or 'iptables-restore --help' for more information.
sysctl: setting key "net.ipv4.conf.all.accept_redirects": Read-only file system
sysctl: setting key "net.ipv4.conf.default.accept_redirects": Read-only file system
sysctl: setting key "net.ipv6.conf.all.accept_redirects": Read-only file system
sysctl: setting key "net.ipv6.conf.default.accept_redirects": Read-only file system
sysctl: setting key "net.ipv4.icmp_echo_ignore_broadcasts": Read-only file system
sysctl: setting key "net.ipv4.icmp_ignore_bogus_error_responses": Read-only file system
sysctl: setting key "net.ipv4.icmp_echo_ignore_all": Read-only file system
sysctl: setting key "net.ipv4.conf.all.log_martians": Read-only file system
sysctl: setting key "net.ipv4.conf.default.log_martians": Read-only file system
Problem loading ipv6 (skipping)
Problem running '/etc/ufw/before.rules'
Problem running '/etc/ufw/after.rules'
Problem running '/etc/ufw/user.rules'
root@94d82c9ba002:/#
sudo ufw reload
Firewall not enabled (skipping reload)
root@66548e7316fc:/#正如您在上面的命令提示符中看到的那样，我已经是 root 用户了。