我无法使用 FTPS 连接到我的服务器。我注意到端口 990 未打开。当我尝试通过端口号 990 连接到我的服务器时，我收到以下信息：
telnet myip 990
Connecting To myip...Could not open connection to the host, on port 990: Connect failed
我可以通过端口 21 远程登录到同一台服务器。
如何在我的 ubuntu 服务器上打开端口 990？
防火墙处于非活动状态：
ubuntu@ip: sudo ufw status
Status: inactive
以下是我得到的 iptables 信息：
ubuntu@ip:sudo iptables -L
Chain INPUT (policy ACCEPT)
target prot opt source destination
Chain FORWARD (policy ACCEPT)
target prot opt source destination
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
这是我从 apparmor 获得的信息：
ubuntu@ip: sudo aa-status
apparmor module is loaded.
22 profiles are loaded.
20 profiles are in enforce mode.
/sbin/dhclient
/snap/core/11993/usr/lib/snapd/snap-confine
/snap/core/11993/usr/lib/snapd/snap-confine//mount-namespace-capture-helper
/usr/bin/lxc-start
/usr/bin/man
/usr/lib/NetworkManager/nm-dhcp-client.action
/usr/lib/NetworkManager/nm-dhcp-helper
/usr/lib/connman/scripts/dhclient-script
/usr/lib/snapd/snap-confine
/usr/lib/snapd/snap-confine//mount-namespace-capture-helper
/usr/sbin/tcpdump
lxc-container-default
lxc-container-default-cgns
lxc-container-default-with-mounting
lxc-container-default-with-nesting
man_filter
man_groff
snap-update-ns.amazon-ssm-agent
snap-update-ns.core
snap.core.hook.configure
2 profiles are in complain mode.
snap.amazon-ssm-agent.amazon-ssm-agent
snap.amazon-ssm-agent.ssm-cli
2 processes have profiles defined.
0 processes are in enforce mode.
2 processes are in complain mode.
snap.amazon-ssm-agent.amazon-ssm-agent (814)
snap.amazon-ssm-agent.amazon-ssm-agent (1034)
0 processes are unconfined but have a profile defined.
该服务器是一个EC2实例，我也在安全组中定义了以下规则：
