Ubuntu 20.04.3 LTS 无法开放端口

[nostalgiain1989]

iptables和ufw都试过了，没有办法开放端口21或者其他端口，想问一下大概是什么原因

系统是阿里云上的Ubuntu 20.04.3 LTS (GNU/Linux 5.4.0-100-generic x86_64)

root@CloudServer2022:~# ufw status
Status: active

To Action From
-- ------ ----
22 ALLOW Anywhere
21 ALLOW Anywhere
3389 ALLOW Anywhere
22 (v6) ALLOW Anywhere (v6)
21 (v6) ALLOW Anywhere (v6)
3389 (v6) ALLOW Anywhere (v6)


root@CloudServer2022:~# iptables -I INPUT -p tcp --dport 21 -j ACCEPT
root@CloudServer2022:~# iptables -I OUTPUT -p tcp --sport 21 -j ACCEPT
root@CloudServer2022:~# iptables-save

root@CloudServer2022:~# netstat -nl
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 127.0.0.53:53 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN
udp 0 0 127.0.0.1:323 0.0.0.0:*
udp 0 0 127.0.0.53:53 0.0.0.0:*
udp 0 0 172.21.224.120:68 0.0.0.0:*
udp6 0 0 ::1:323 :::*
raw6 0 0 :::58 :::* 7
Active UNIX domain sockets (only servers)
Proto RefCnt Flags Type State I-Node Path
unix 2 [ ACC ] SEQPACKET LISTENING 13352 /run/udev/control
unix 2 [ ACC ] STREAM LISTENING 13324 /run/systemd/private
unix 2 [ ACC ] STREAM LISTENING 13326 /run/systemd/userdb/io.systemd.DynamicUser
unix 2 [ ACC ] STREAM LISTENING 13337 /run/systemd/fsck.progress
unix 2 [ ACC ] STREAM LISTENING 33072 /run/user/0/systemd/private
unix 2 [ ACC ] STREAM LISTENING 13347 /run/systemd/journal/stdout
unix 2 [ ACC ] STREAM LISTENING 33079 /run/user/0/gnupg/S.dirmngr
unix 2 [ ACC ] STREAM LISTENING 33080 /run/user/0/gnupg/S.gpg-agent.browser
unix 2 [ ACC ] STREAM LISTENING 33081 /run/user/0/gnupg/S.gpg-agent.extra
unix 2 [ ACC ] STREAM LISTENING 33082 /run/user/0/gnupg/S.gpg-agent.ssh
unix 2 [ ACC ] STREAM LISTENING 33083 /run/user/0/gnupg/S.gpg-agent
unix 2 [ ACC ] STREAM LISTENING 14154 /run/systemd/journal/io.systemd.journal
unix 2 [ ACC ] STREAM LISTENING 20448 /usr/local/aegis/Aegis-<Guid(5A2C30A2-A87D-490A-9281-6765EDAD7CBA)>
unix 2 [ ACC ] STREAM LISTENING 17204 /run/dbus/system_bus_socket
unix 2 [ ACC ] STREAM LISTENING 17216 /run/uuidd/request

[oneleaf]

没有安装 ftp 服务。话说现在很少人使用ftp传文件，都是sftp直接传。