这是一台 Ubuntu 服务器 20.04.2，位于家庭网络中。主要用于测试和非破坏性实验（php、python 学习、虚拟机等），用作我工作电脑旁边的无头机器。
安装 iRedMail 后出现问题。显然，我立即卸载了它并清除了所有组件。在发现这并没有解决问题后，我尝试从一周前的备份中恢复 etc 文件夹。令人惊讶的是，这并没有杀死操作系统，一切都正常，除了……除了 ssh 之外的一切都被阻止了。
以下是 nmap 的输出：
Host is up (0.0000090s latency).
Not shown: 985 closed ports
PORT STATE SERVICE
21/tcp open ftp
22/tcp open ssh
25/tcp open smtp
53/tcp open domain
110/tcp open pop3
139/tcp open netbios-ssn
143/tcp open imap
445/tcp open microsoft-ds
465/tcp open smtps
587/tcp open submission
993/tcp open imaps
995/tcp open pop3s
2222/tcp open EtherNetIP-1
3389/tcp open ms-wbt-server
8333/tcp open bitcoin
iptables -v -x -n -L 输出：
Chain INPUT (policy ACCEPT 866112 packets, 1230088617 bytes)
pkts bytes target prot opt in out source destination
2056 148363 ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:22 ctstate NEW,ESTABLISHED
Chain FORWARD (policy DROP 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
0 0 DOCKER-USER all -- * * 0.0.0.0/0 0.0.0.0/0
0 0 DOCKER-ISOLATION-STAGE-1 all -- * * 0.0.0.0/0 0.0.0.0/0
0 0 ACCEPT all -- * docker0 0.0.0.0/0 0.0.0.0/0 ctstate RELATED,ESTABLISHED
0 0 DOCKER all -- * docker0 0.0.0.0/0 0.0.0.0/0
0 0 ACCEPT all -- docker0 !docker0 0.0.0.0/0 0.0.0.0/0
0 0 ACCEPT all -- docker0 docker0 0.0.0.0/0 0.0.0.0/0
Chain OUTPUT (policy ACCEPT 453277 packets, 38601280 bytes)
pkts bytes target prot opt in out source destination
2 84 ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:22 ctstate NEW,ESTABLISHED
Chain DOCKER (1 references)
pkts bytes target prot opt in out source destination
Chain DOCKER-ISOLATION-STAGE-1 (1 references)
pkts bytes target prot opt in out source destination
0 0 DOCKER-ISOLATION-STAGE-2 all -- docker0 !docker0 0.0.0.0/0 0.0.0.0/0
0 0 RETURN all -- * * 0.0.0.0/0 0.0.0.0/0
Chain DOCKER-ISOLATION-STAGE-2 (1 references)
pkts bytes target prot opt in out source destination
0 0 DROP all -- * docker0 0.0.0.0/0 0.0.0.0/0
0 0 RETURN all -- * * 0.0.0.0/0 0.0.0.0/0
Chain DOCKER-USER (1 references)
pkts bytes target prot opt in out source destination
0 0 RETURN all -- * * 0.0.0.0/0 0.0.0.0/0
Chain FORWARD_IN_ZONES (0 references)
pkts bytes target prot opt in out source destination
Chain FORWARD_OUT_ZONES (0 references)
pkts bytes target prot opt in out source destination
Chain FORWARD_direct (0 references)
pkts bytes target prot opt in out source destination
Chain FWDI_public (0 references)
pkts bytes target prot opt in out source destination
Chain FWDI_public_allow (0 references)
pkts bytes target prot opt in out source destination
Chain FWDI_public_deny (0 references)
pkts bytes target prot opt in out source destination
Chain FWDI_public_log (0 references)
pkts bytes target prot opt in out source destination
Chain FWDI_public_log (0 references)
pkts bytes target prot opt in out source destination
Chain FWDI_public_post (0 references)
pkts bytes target prot opt in out source destination
Chain FWDI_public_pre (0 references)
pkts bytes target prot opt in out source destination
Chain FWDO_public (0 references)
pkts bytes target prot opt in out source destination
Chain FWDO_public_allow (0 references)
pkts bytes target prot opt in out source destination
Chain FWDO_public_deny (0 references)
pkts bytes target prot opt in out source destination
Chain FWDO_public_log (0 references)
pkts bytes target prot opt in out source destination
Chain FWDO_public_post (0 references)
pkts bytes target prot opt in out source destination
Chain FWDO_public_pre (0 references)
pkts bytes target prot opt in out source destination
Chain INPUT_ZONES (0 references)
pkts bytes target prot opt in out source destination
Chain INPUT_direct (0 references)
pkts bytes target prot opt in out source destination
Chain IN_public (0 references)
pkts bytes target prot opt in out source destination
Chain IN_public_allow (0 references)
pkts bytes target prot opt in out source destination
Chain IN_public_deny (0 references)
pkts bytes target prot opt in out source destination
Chain IN_public_log (0 references)
pkts bytes target prot opt in out source destination
Chain IN_public_post (0 references)
pkts bytes target prot opt in out source destination
Chain IN_public_pre (0 references)
pkts bytes target prot opt in out source destination
Chain OUTPUT_direct (0 references)
pkts bytes target prot opt in out source destination
除了 ssh，无法连接任何其他设备。没有 xrdp，没有 smbd。Ping 正常，丢失率为 0%。
我错过了什么？