我正在尝试通过密钥从另一台 Ubuntu 机器登录到 Ubuntu 服务器。
我在客户端做了什么：
ssh-keygen -t rsa # generate ssh key
在服务器上/etc/ssh/sshd_config：
# 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 DEBUG3
# Authentication:
LoginGraceTime 120
PermitRootLogin yes
StrictModes yes
RSAAuthentication yes
PubkeyAuthentication yes
AuthorizedKeysFile /etc/ssh/keys/%u/autherized_keys2
# 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
Match User MyUser
PasswordAuthentication no
Match all
/etc/ssh/keys/MyUser/autherized_keys2：
ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDRcr3RQzythTCGfICWqMMGlPRLCBzZi9Wq/1+3+lhQofhcvj6p93/pXNR/SfeDYAnRa51MgU3nwa90CcJuNsZkUIY8PFStu0Uw3fkGkitpBJ10ACRyg4yMT0OGtDe5zOVJlkmZNNn5rAjYZ4xiTdZIZ55/UgMwTL2u7w+p0ET/ankajaW5KwuRdZLI4+PSZHJ94ZtvwyY8DEIDVYoIpp5j2m7QJCmrEc4PBWbxTExSQlD6ONwGlBECwCbxXE2jRBxu4Ox7m6XzKtlLytVOFX8g+K2tnyurYo0Nvi14GXweOdiYQtcbJYsh7QsfzH230yzxXT1MaOWaMzgXTO5WgusZ MyUser@Infra-L-Omer-a-Ubuntu
这与客户端中的完全相同id_rsa.pub。客户端尝试登录（-vvv详细模式）中的输出：
$ sudo ssh -vvv -2 -o StrictHostKeyChecking=no -i /home/MyUser/.ssh/id_rsa MyUser@***.**.**.** -p 555 # the command to log in [** is my IP]
OpenSSH_7.2p2 Ubuntu-4ubuntu2.1, OpenSSL 1.0.2g 1 Mar 2016
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: Applying options for *
debug2: resolving "**.**.**.**" port 555
debug2: ssh_connect_direct: needpriv 0
debug1: Connecting to **.**.**.** [**.**.**.**] port 555.
debug1: Connection established.
debug1: identity file /home/MyUser/.ssh/id_rsa type 1
debug1: key_load_public: No such file or directory
debug1: identity file /home/MyUser/.ssh/id_rsa-cert type -1
debug1: identity file /home/MyUser/.ssh/id_rsa type 1
debug1: key_load_public: No such file or directory
debug1: identity file /home/MyUser/.ssh/id_rsa-cert type -1
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_7.2p2 Ubuntu-4ubuntu2.1
debug1: Remote protocol version 2.0, remote software version OpenSSH_7.2p2 Ubuntu-4ubuntu2.4
debug1: match: OpenSSH_7.2p2 Ubuntu-4ubuntu2.4 pat OpenSSH* compat 0x04000000
debug2: fd 3 setting O_NONBLOCK
debug1: Authenticating to **.**.**.**:555 as 'MyUser'
debug3: put_host_port: [**.**.**.**]:555
debug3: hostkeys_foreach: reading file "/home/MyUser/.ssh/known_hosts"
debug3: record_hostkey: found key type ECDSA in file /home/MyUser/.ssh/known_hosts:7
debug3: load_hostkeys: loaded 1 keys from [**.**.**.**]:555
debug3: order_hostkeyalgs: prefer hostkeyalgs: [email protected],[email protected],[email protected],ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521
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: [email protected],ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,ext-info-c
debug2: host key algorithms: [email protected],[email protected],[email protected],ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,[email protected],[email protected],ssh-ed25519,rsa-sha2-512,rsa-sha2-256,ssh-rsa
debug2: ciphers ctos: [email protected],aes128-ctr,aes192-ctr,aes256-ctr,[email protected],[email protected],aes128-cbc,aes192-cbc,aes256-cbc,3des-cbc
debug2: ciphers stoc: [email protected],aes128-ctr,aes192-ctr,aes256-ctr,[email protected],[email protected],aes128-cbc,aes192-cbc,aes256-cbc,3des-cbc
debug2: MACs ctos: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: MACs stoc: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: compression ctos: none,[email protected],zlib
debug2: compression stoc: none,[email protected],zlib
debug2: languages ctos:
debug2: languages stoc:
debug2: first_kex_follows 0
debug2: reserved 0
debug2: peer server KEXINIT proposal
debug2: KEX algorithms: [email protected],ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha1
debug2: host key algorithms: ssh-rsa,rsa-sha2-512,rsa-sha2-256,ecdsa-sha2-nistp256,ssh-ed25519
debug2: ciphers ctos: [email protected],aes128-ctr,aes192-ctr,aes256-ctr,[email protected],[email protected]
debug2: ciphers stoc: [email protected],aes128-ctr,aes192-ctr,aes256-ctr,[email protected],[email protected]
debug2: MACs ctos: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: MACs stoc: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: compression ctos: none,[email protected]
debug2: compression stoc: none,[email protected]
debug2: languages ctos:
debug2: languages stoc:
debug2: first_kex_follows 0
debug2: reserved 0
debug1: kex: algorithm: [email protected]
debug1: kex: host key algorithm: ecdsa-sha2-nistp256
debug1: kex: server->client cipher: [email protected] MAC: <implicit> compression: none
debug1: kex: client->server cipher: [email protected] MAC: <implicit> compression: none
debug3: send packet: type 30
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug3: receive packet: type 31
debug1: Server host key: ecdsa-sha2-nistp256 SHA256:WOX/Lg+OQsBxFeIEh7jOZ/2005b4uVe+Ox/39/6MfCA
debug3: put_host_port: [**.**.**.**]:555
debug3: put_host_port: [**.**.**.**]:555
debug3: hostkeys_foreach: reading file "/home/MyUser/.ssh/known_hosts"
debug3: record_hostkey: found key type ECDSA in file /home/MyUser/.ssh/known_hosts:7
debug3: load_hostkeys: loaded 1 keys from [**.**.**.**]:555
debug3: hostkeys_foreach: reading file "/home/MyUser/.ssh/known_hosts"
debug3: record_hostkey: found key type ECDSA in file /home/MyUser/.ssh/known_hosts:7
debug3: load_hostkeys: loaded 1 keys from [**.**.**.**]:555
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
Someone could be eavesdropping on you right now (man-in-the-middle attack)!
It is also possible that a host key has just been changed.
The fingerprint for the ECDSA key sent by the remote host is
SHA256:WOX/Lg+OQsBxFeIEh7jOZ/2005b4uVe+Ox/39/6MfCA.
Please contact your system administrator.
Add correct host key in /home/MyUser/.ssh/known_hosts to get rid of this message.
Offending ECDSA key in /home/MyUser/.ssh/known_hosts:7
remove with:
ssh-keygen -f "/home/MyUser/.ssh/known_hosts" -R [**.**.**.**]:555
Password authentication is disabled to avoid man-in-the-middle attacks.
Keyboard-interactive authentication is disabled to avoid man-in-the-middle attacks.
debug3: send packet: type 21
debug2: set_newkeys: mode 1
debug1: rekey after 134217728 blocks
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug3: receive packet: type 21
debug2: set_newkeys: mode 0
debug1: rekey after 134217728 blocks
debug1: SSH2_MSG_NEWKEYS received
debug2: key: /home/MyUser/.ssh/id_rsa (0x556c348b7200), explicit
debug2: key: /home/MyUser/.ssh/id_rsa (0x556c34904110)
debug3: send packet: type 5
debug3: receive packet: type 7
debug1: SSH2_MSG_EXT_INFO received
debug1: kex_input_ext_info: server-sig-algs=<rsa-sha2-256,rsa-sha2-512>
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
debug3: start over, passed a different list publickey
debug3: preferred gssapi-keyex,gssapi-with-mic,publickey
debug3: authmethod_lookup publickey
debug3: remaining preferred: ,gssapi-with-mic,publickey
debug3: authmethod_is_enabled publickey
debug1: Next authentication method: publickey
debug1: Offering RSA public key: /home/MyUser/.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
debug1: Offering RSA public key: /home/MyUser/.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
debug2: we did not send a packet, disable method
debug1: No more authentication methods to try.
Permission denied (publickey).
为了使密钥验证能够正常工作，我必须进行哪些更改？
答案1
这是我从电脑连接到服务器的方式：
pcuser@pchostname:~$ssh-keygen
创建两个文件，分别/home/pcuser/.ssh/称为id_rsa（私钥）和id_rsa.pub（公钥）
创建一个文件，如果它尚不存在，则调用/home/pcuser/.ssh/config并添加您的服务器的信息：
Host myserver
HostName myserverIP
User myserverUser
Port 22
IdentityFile ~/.ssh/id_rsa
Port 22和IdentityFile ~/.ssh/id_rsa是默认值。仅当您使用与默认值不同的值时才需要指定它们。
现在将你电脑的公钥复制到你的服务器。系统将要求你将其存储为已知主机，并要求你输入服务器用户密码
pcuser@pchostname:~/$ssh-copy-id -i ~/.ssh/id_rsa.pub myserver
现在，您可以使用 ssh 连接到您的服务器
pcuser@pchostnamme:~/$ssh myserver
它不应再要求输入密码。
看看ssh 配置文件文档以获得更多选项。一些有趣的选项（尽管它们可能不安全）是：
Host *
StrictHostKeyChecking no
UserKnownHostsFile=/dev/null
ControlPersist 8h
它们写在配置文件的末尾，并适用于所有没有在文件中明确设置这些设置的主机。
答案2
您可能将服务器的 IP 更改为已知的连接。
警告称：
远程主机标识已改变！
您可以按照说明进行修复：
ssh-keygen -f "/home/MyUser/.ssh/known_hosts" -R [。。。]：555
并重试连接。