幾個月前，我終於在我的伺服器上升級了 18.04。它是 OVH 託管的虛擬機器。安裝完成後，我重新啟動了虛擬機器。正如我擔心的那樣，我無法使用 SSH 連線。
升級之前，我使用連接埠 44 連接到虛擬機，並使用 ufw 作為防火牆來阻止來自 22 連接埠的所有連接並允許來自 44 連接埠的連接。在升級過程中，我被問到是否要過度加載 sshd 配置文件，我選擇不這樣做。
對我來說「幸運」的是，OVH 允許您在救援模式下重新啟動虛擬機器。這樣，我就能夠連接到我的虛擬機，並透過命令mount /dev/sda2/ /mnt/，我可以存取我的根目錄。
我嘗試刪除 sshd 配置或 ufw 檔案中有關阻止連接埠 22 和允許連接埠 44 的所有行。
什麼都不起作用。
這是我的使用者規則：
*filter
:ufw-user-input - [0:0]
:ufw-user-output - [0:0]
:ufw-user-forward - [0:0]
:ufw-before-logging-input - [0:0]
:ufw-before-logging-output - [0:0]
:ufw-before-logging-forward - [0:0]
:ufw-user-logging-input - [0:0]
:ufw-user-logging-output - [0:0]
:ufw-user-logging-forward - [0:0]
:ufw-after-logging-input - [0:0]
:ufw-after-logging-output - [0:0]
:ufw-after-logging-forward - [0:0]
:ufw-logging-deny - [0:0]
:ufw-logging-allow - [0:0]
:ufw-user-limit - [0:0]
:ufw-user-limit-accept - [0:0]
### RULES ###
### tuple ### allow tcp 22 0.0.0.0/0 any 0.0.0.0/0 in
-A ufw-user-input -p tcp --dport 22 -j ACCEPT
### tuple ### allow tcp 44 0.0.0.0/0 any 0.0.0.0/0 in
-A ufw-user-input -p tcp --dport 44 -j ACCEPT
### END RULES ###
### LOGGING ###
-A ufw-after-logging-input -j LOG --log-prefix "[UFW BLOCK] " -m limit --limit 3/min --limit-burst 10
-A ufw-after-logging-forward -j LOG --log-prefix "[UFW BLOCK] " -m limit --limit 3/min --limit-burst 10
-I ufw-logging-deny -m conntrack --ctstate INVALID -j RETURN -m limit --limit 3/min --limit-burst 10
-A ufw-logging-deny -j LOG --log-prefix "[UFW BLOCK] " -m limit --limit 3/min --limit-burst 10
-A ufw-logging-allow -j LOG --log-prefix "[UFW ALLOW] " -m limit --limit 3/min --limit-burst 10
### END LOGGING ###
### RATE LIMITING ###
-A ufw-user-limit -m limit --limit 3/minute -j LOG --log-prefix "[UFW LIMIT BLOCK] "
-A ufw-user-limit -j REJECT
-A ufw-user-limit-accept -j ACCEPT
### END RATE LIMITING ###
COMMIT
這是我的 sshd_config 檔案：
# Package generated configuration file
# See the sshd_config(5) manpage for details
# What ports, IPs and protocols we listen for
Port 22,44
# Use these options to restrict which interfaces/protocols sshd will bind to
#ListenAddress ::
#ListenAddress 0.0.0.0
Protocol 2
# HostKeys for protocol version 2
HostKey /etc/ssh/ssh_host_rsa_key
#HostKey /etc/ssh/ssh_host_dsa_key
#HostKey /etc/ssh/ssh_host_ecdsa_key
HostKey /etc/ssh/ssh_host_ed25519_key
#Privilege Separation is turned on for security
UsePrivilegeSeparation yes
# Lifetime and size of ephemeral version 1 server key
KeyRegenerationInterval 3600
ServerKeyBits 1024
# Logging
SyslogFacility AUTH
LogLevel INFO
# Authentication:
LoginGraceTime 120
PermitRootLogin no
StrictModes yes
MaxStartups 5:15:30
AllowUsers myuser
RSAAuthentication yes
PubkeyAuthentication yes
#AuthorizedKeysFile %h/.ssh/authorized_keys
# Don't read the user's ~/.rhosts and ~/.shosts files
IgnoreRhosts yes
# For this to work you will also need host keys in /etc/ssh_known_hosts
RhostsRSAAuthentication no
# similar for protocol version 2
HostbasedAuthentication no
# Uncomment if you don't trust ~/.ssh/known_hosts for RhostsRSAAuthentication
#IgnoreUserKnownHosts yes
# To enable empty passwords, change to yes (NOT RECOMMENDED)
PermitEmptyPasswords no
# Change to yes to enable challenge-response passwords (beware issues with
# some PAM modules and threads)
ChallengeResponseAuthentication no
# Change to no to disable tunnelled clear text passwords
PasswordAuthentication yes #no
# Kerberos options
#KerberosAuthentication no
#KerberosGetAFSToken no
#KerberosOrLocalPasswd yes
#KerberosTicketCleanup yes
# GSSAPI options
#GSSAPIAuthentication no
#GSSAPICleanupCredentials yes
X11Forwarding no
X11DisplayOffset 10
PrintMotd no
PrintLastLog yes
TCPKeepAlive yes
#UseLogin no
#Banner /etc/issue.net
# Allow client to pass locale environment variables
AcceptEnv LANG LC_*
Subsystem sftp /usr/lib/openssh/sftp-server
# Set this to 'yes' to enable PAM authentication, account processing,
# and session processing. If this is enabled, PAM authentication will
# be allowed through the ChallengeResponseAuthentication and
# PasswordAuthentication. Depending on your PAM configuration,
# PAM authentication via ChallengeResponseAuthentication may bypass
# the setting of "PermitRootLogin without-password".
# If you just want the PAM account and session checks to run without
# PAM authentication, then enable this but set PasswordAuthentication
# and ChallengeResponseAuthentication to 'no'.
UsePAM yes
Ciphers [email protected],[email protected],aes256-ctr,aes128-ctr
MACs [email protected],[email protected],[email protected],hmac-sha2-512,hmac-sha2-256,hmac-ripemd160,hmac-sha1
KexAlgorithms diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha1,diffie-hellman-group-exchange-sha1,diffie-hellman-group1-sha1
最後一件事，ssh目錄包含很多設定檔：
rescue:/mnt/etc/ssh# ls
moduli ssh_config.dpkg-dist sshd_config.orig ssh_host_dsa_key ssh_host_ecdsa_key ssh_host_ed25519_key ssh_host_key ssh_host_rsa_key ssh_import_id
ssh_config sshd_config sshd_config.ucf-dist ssh_host_dsa_key.pub ssh_host_ecdsa_key.pub ssh_host_ed25519_key.pub ssh_host_key.pub ssh_host_rsa_key.pub
哪裡有問題？我開始認為重啟後，UFW 不會加載配置並且仍然使用舊版本。或多個 sshd_config 文件，即使它們允許連接埠 22。
感謝您的協助