ssh 連接到 ssh 伺服器在 LAN 內工作，但不是從 Internet

我在我的 ubuntu 伺服器上安裝了 openssh 伺服器，它位於 fritzbox 路由器後面。sshd_config 是：

# Package generated configuration file
# See the sshd_config(5) manpage for details

# What ports, IPs and protocols we listen for
Port 22
# 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 yes
StrictModes yes

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

# Kerberos options
#KerberosAuthentication no
#KerberosGetAFSToken no
#KerberosOrLocalPasswd yes
#KerberosTicketCleanup yes

# GSSAPI options
#GSSAPIAuthentication no
#GSSAPICleanupCredentials yes

X11Forwarding yes
X11DisplayOffset 10
PrintMotd no
PrintLastLog yes
TCPKeepAlive yes
#UseLogin no

#MaxStartups 10:30:60
#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

所以我完全能夠從我的區域網路內連接到伺服器，但我想從網際網路內的任何地方連接到我的家庭伺服器。所以我使用了一個 dyndns 伺服器，它執行良好。從我可以執行的任何地方：

nc -z blabla.selfhost.co 22
Connection to blabla.selfhost.co port 22 [tcp/ssh] succeeded

現在這裡是 ssh 命令的詳細輸出

ssh -vvv bla@blabla.selfhost.co

OpenSSH_7.7p1, LibreSSL 2.7.3
debug1: Reading configuration data /Users/BLA/.ssh/config
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 48: Applying options for *
debug2: ssh_connect_direct: needpriv 0
debug1: Connecting to blabla.selfhost.co port 22.
debug1: Connection established.
debug1: identity file /Users/BLA/.ssh/id_rsa type 0
debug1: key_load_public: No such file or directory
debug1: identity file /Users/BLA/.ssh/id_rsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/BLA/.ssh/id_dsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/BLA/.ssh/id_dsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/BLA/.ssh/id_ecdsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/BLA/.ssh/id_ecdsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/BLA/.ssh/id_ed25519 type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/BLA/.ssh/id_ed25519-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/BLA/.ssh/id_xmss type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/BLA/.ssh/id_xmss-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_7.7
debug1: Remote protocol version 2.0, remote software version OpenSSH_5.3
debug1: match: OpenSSH_5.3 pat OpenSSH_5* compat 0x0c000000
debug3: fd 5 is O_NONBLOCK
debug1: Authenticating to blabla.selfhost.co:22 as 'bla'
debug3: hostkeys_foreach: reading file "/Users/BLA/.ssh/known_hosts"
debug3: record_hostkey: found key type RSA in file /Users/BLA/.ssh/known_hosts:18
debug3: load_hostkeys: loaded 1 keys from blabla.selfhost.co
debug3: order_hostkeyalgs: prefer hostkeyalgs: ssh-rsa-cert-v01@openssh.com,rsa-sha2-512,rsa-sha2-256,ssh-rsa
debug3: send packet: type 20
debug1: SSH2_MSG_KEXINIT sent
debug3: receive packet: type 20
debug1: SSH2_MSG_KEXINIT received
debug2: local client KEXINIT proposal
debug2: KEX algorithms: curve25519-sha256,curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha256,diffie-hellman-group14-sha1,ext-info-c
debug2: host key algorithms: ssh-rsa-cert-v01@openssh.com,rsa-sha2-512,rsa-sha2-256,ssh-rsa,ecdsa-sha2-nistp256-cert-v01@openssh.com,ecdsa-sha2-nistp384-cert-v01@openssh.com,ecdsa-sha2-nistp521-cert-v01@openssh.com,ssh-ed25519-cert-v01@openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,ssh-ed25519
debug2: ciphers ctos: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com
debug2: ciphers stoc: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com
debug2: MACs ctos: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: MACs stoc: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: compression ctos: none,zlib@openssh.com,zlib
debug2: compression stoc: none,zlib@openssh.com,zlib
debug2: languages ctos: 
debug2: languages stoc: 
debug2: first_kex_follows 0 
debug2: reserved 0 
debug2: peer server KEXINIT proposal
debug2: KEX algorithms: diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1
debug2: host key algorithms: ssh-rsa,ssh-dss
debug2: ciphers ctos: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,rijndael-cbc@lysator.liu.se
debug2: ciphers stoc: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,rijndael-cbc@lysator.liu.se
debug2: MACs ctos: hmac-md5,hmac-sha1,umac-64@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96
debug2: MACs stoc: hmac-md5,hmac-sha1,umac-64@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96
debug2: compression ctos: none,zlib@openssh.com
debug2: compression stoc: none,zlib@openssh.com
debug2: languages ctos: 
debug2: languages stoc: 
debug2: first_kex_follows 0 
debug2: reserved 0 
debug1: kex: algorithm: diffie-hellman-group-exchange-sha256
debug1: kex: host key algorithm: ssh-rsa
debug1: kex: server->client cipher: aes128-ctr MAC: umac-64@openssh.com compression: none
debug1: kex: client->server cipher: aes128-ctr MAC: umac-64@openssh.com compression: none
debug3: send packet: type 34
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(2048<3072<8192) sent
debug3: receive packet: type 31
debug1: got SSH2_MSG_KEX_DH_GEX_GROUP
debug2: bits set: 1569/3072
debug3: send packet: type 32
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug3: receive packet: type 33
debug1: got SSH2_MSG_KEX_DH_GEX_REPLY
debug1: Server host key: ssh-rsa SHA256:stKU5NgYR5Vs8jsCLIpvdy0cO6Wze5KY0sj0+2ng5WA
debug3: hostkeys_foreach: reading file "/Users/BLA/.ssh/known_hosts"
debug3: record_hostkey: found key type RSA in file /Users/BLA/.ssh/known_hosts:18
debug3: load_hostkeys: loaded 1 keys from blabla.selfhost.co
debug3: hostkeys_foreach: reading file "/Users/BLA/.ssh/known_hosts"
debug3: record_hostkey: found key type RSA in file /Users/BLA/.ssh/known_hosts:18
debug3: load_hostkeys: loaded 1 keys from 83.169.40.234
debug1: Host 'blabla.selfhost.co' is known and matches the RSA host key.
debug1: Found key in /Users/BLA/.ssh/known_hosts:18
debug2: bits set: 1548/3072
debug3: send packet: type 21
debug2: set_newkeys: mode 1
debug1: rekey after 4294967296 blocks
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug3: receive packet: type 21
debug1: SSH2_MSG_NEWKEYS received
debug2: set_newkeys: mode 0
debug1: rekey after 4294967296 blocks
debug2: key: /Users/BLA/.ssh/id_rsa (0x7f993c0017b0)
debug2: key: /Users/BLA/.ssh/id_dsa (0x0)
debug2: key: /Users/BLA/.ssh/id_ecdsa (0x0)
debug2: key: /Users/BLA/.ssh/id_ed25519 (0x0)
debug2: key: /Users/BLA/.ssh/id_xmss (0x0)
debug3: send packet: type 5
debug3: receive packet: type 6
debug2: service_accept: ssh-userauth
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug3: send packet: type 50
debug3: receive packet: type 51
debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password
debug3: start over, passed a different list publickey,gssapi-keyex,gssapi-with-mic,password
debug3: preferred publickey,keyboard-interactive,password
debug3: authmethod_lookup publickey
debug3: remaining preferred: keyboard-interactive,password
debug3: authmethod_is_enabled publickey
debug1: Next authentication method: publickey
debug1: Offering public key: RSA SHA256:bITNYUVDZe1M0/0G8xHsrNbI+zPWO3A6NLzC6PSq7z8 /Users/BLA/.ssh/id_rsa
debug3: send_pubkey_test
debug3: send packet: type 50
debug2: we sent a publickey packet, wait for reply
debug3: receive packet: type 51
debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password
debug1: Trying private key: /Users/BLA/.ssh/id_dsa
debug3: no such identity: /Users/BLA/.ssh/id_dsa: No such file or directory
debug1: Trying private key: /Users/BLA/.ssh/id_ecdsa
debug3: no such identity: /Users/BLA/.ssh/id_ecdsa: No such file or directory
debug1: Trying private key: /Users/BLA/.ssh/id_ed25519
debug3: no such identity: /Users/BLA/.ssh/id_ed25519: No such file or directory
debug1: Trying private key: /Users/BLA/.ssh/id_xmss
debug3: no such identity: /Users/BLA/.ssh/id_xmss: No such file or directory
debug2: we did not send a packet, disable method
debug3: authmethod_lookup password
debug3: remaining preferred: ,password
debug3: authmethod_is_enabled password
debug1: Next authentication method: password
bla@blabla.selfhost.co's password: 
debug3: send packet: type 50
debug2: we sent a password packet, wait for reply
debug3: receive packet: type 51
debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password
Permission denied, please try again.

/var/log/auth.log 沒有顯示任何嘗試的跡象，我按照指示打開了防火牆。我哪裡錯了？

問題在於 IPv4 必須通過隧道連接到 IPv6。我採用的解決方案是：

1. 以每月 1 歐元的價格獲得一個 vServer (IP == vServerIP4)
2. 在我的家庭伺服器上將 /etc/ssh/sshd_config 中 ssh 的標準埠更改為 23（IP == homeSeverIP6）
3. 在防火牆中打開該埠並將其轉發到我的路由器上。
4. 在虛擬伺服器上執行“6tunnel 23 homeSeverIP6 23”
5. 通過“ssh -p 23 Kai@vServerIP4”連接到我的 homeServer

感謝@raj 的幫助！

引用自：https://serverfault.com/questions/1061653