我无法通过 SSH 进入服务器A，任何运行 RHEL 8.4 的用户都可以使用。上周它运行良好。/var/log/secure 或 systemctl status sshd 中没有显示任何内容 - /etch/sshd_config 设置为允许 PasswordAuthentication。它从不要求输入任何密码 - 在 PuTTY 上，它在输入用户名后立即关闭，在命令行上，它只是失败并显示“serverA 关闭了连接”
运行 ssh -v root@server 时，我得到以下输出：
OpenSSH_for_Windows_8.6p1, LibreSSL 3.4.3
debug1: Authenticator provider $SSH_SK_PROVIDER did not resolve; disabling
debug1: Connecting to serverA [serverA] port 22.
debug1: Connection established.
debug1: identity file C:\\Users\\userA/.ssh/id_rsa type -1
debug1: identity file C:\\Users\\userA/.ssh/id_rsa-cert type -1
debug1: identity file C:\\Users\\userA/.ssh/id_dsa type -1
debug1: identity file C:\\Users\\userA/.ssh/id_dsa-cert type -1
debug1: identity file C:\\Users\\userA/.ssh/id_ecdsa type -1
debug1: identity file C:\\Users\\userA/.ssh/id_ecdsa-cert type -1
debug1: identity file C:\\Users\\userA/.ssh/id_ecdsa_sk type -1
debug1: identity file C:\\Users\\userA/.ssh/id_ecdsa_sk-cert type -1
debug1: identity file C:\\Users\\userA/.ssh/id_ed25519 type -1
debug1: identity file C:\\Users\\userA/.ssh/id_ed25519-cert type -1
debug1: identity file C:\\Users\\userA/.ssh/id_ed25519_sk type -1
debug1: identity file C:\\Users\\userA/.ssh/id_ed25519_sk-cert type -1
debug1: identity file C:\\Users\\userA/.ssh/id_xmss type -1
debug1: identity file C:\\Users\\userA/.ssh/id_xmss-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_for_Windows_8.6
debug1: Remote protocol version 2.0, remote software version OpenSSH_8.0
debug1: compat_banner: match: OpenSSH_8.0 pat OpenSSH* compat 0x04000000
debug1: Authenticating to serverA:22 as 'root'
debug1: load_hostkeys: fopen C:\\Users\\userA/.ssh/known_hosts2: No such file or directory
debug1: load_hostkeys: fopen __PROGRAMDATA__\\ssh/ssh_known_hosts: No such file or directory
debug1: load_hostkeys: fopen __PROGRAMDATA__\\ssh/ssh_known_hosts2: No such file or directory
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: algorithm: curve25519-sha256
debug1: kex: host key algorithm: ssh-ed25519
debug1: kex: server->client cipher: [email protected] MAC: <implicit> compression: none
debug1: kex: client->server cipher: [email protected] MAC: <implicit> compression: none
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug1: SSH2_MSG_KEX_ECDH_REPLY received
debug1: load_hostkeys: fopen C:\\Users\\userA/.ssh/known_hosts2: No such file or directory
debug1: load_hostkeys: fopen __PROGRAMDATA__\\ssh/ssh_known_hosts: No such file or directory
debug1: load_hostkeys: fopen __PROGRAMDATA__\\ssh/ssh_known_hosts2: No such file or directory
debug1: Host 'serverA' is known and matches the ED25519 host key.
debug1: Found key in C:\\Users\\userA/.ssh/known_hosts:1
debug1: rekey out after 134217728 blocks
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: rekey in after 134217728 blocks
debug1: pubkey_prepare: ssh_get_authentication_socket: No such file or directory
debug1: Will attempt key: C:\\Users\\userA/.ssh/id_rsa
debug1: Will attempt key: C:\\Users\\userA/.ssh/id_dsa
debug1: Will attempt key: C:\\Users\\userA/.ssh/id_ecdsa
debug1: Will attempt key: C:\\Users\\userA/.ssh/id_ecdsa_sk
debug1: Will attempt key: C:\\Users\\userA/.ssh/id_ed25519
debug1: Will attempt key: C:\\Users\\userA/.ssh/id_ed25519_sk
debug1: Will attempt key: C:\\Users\\userA/.ssh/id_xmss
debug1: SSH2_MSG_EXT_INFO received
debug1: kex_input_ext_info: server-sig-algs=<ssh-ed25519,ssh-rsa,rsa-sha2-256,rsa-sha2-512,ssh-dss,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521>
debug1: SSH2_MSG_SERVICE_ACCEPT received
Connection closed by serverA port 22
在服务器 A 上运行 sshd -ddd 时，我看到以下错误：
userauth-request for user root service ssh-connection method none
完整输出：
debug2: load_server_config: filename /etc/ssh/sshd_config
debug2: load_server_config: done config len = 734
debug2: parse_server_config_depth: config /etc/ssh/sshd_config len 734
debug3: /etc/ssh/sshd_config:22 setting HostKey /etc/ssh/ssh_host_rsa_key
debug3: /etc/ssh/sshd_config:23 setting HostKey /etc/ssh/ssh_host_ecdsa_key
debug3: /etc/ssh/sshd_config:24 setting HostKey /etc/ssh/ssh_host_ed25519_key
debug3: /etc/ssh/sshd_config:37 setting SyslogFacility AUTHPRIV
debug3: /etc/ssh/sshd_config:43 setting PermitRootLogin yes
debug3: /etc/ssh/sshd_config:52 setting AuthorizedKeysFile .ssh/authorized_keys
debug3: /etc/ssh/sshd_config:70 setting PasswordAuthentication yes
debug3: /etc/ssh/sshd_config:74 setting ChallengeResponseAuthentication no
debug3: /etc/ssh/sshd_config:84 setting GSSAPIAuthentication yes
debug3: /etc/ssh/sshd_config:85 setting GSSAPICleanupCredentials no
debug3: /etc/ssh/sshd_config:101 setting UsePAM yes
debug3: /etc/ssh/sshd_config:106 setting X11Forwarding yes
debug3: /etc/ssh/sshd_config:113 setting PrintMotd no
debug3: /etc/ssh/sshd_config:132 setting AcceptEnv LANG LC_CTYPE LC_NUMERIC LC_TIME LC_COLLATE LC_MONETARY LC_MESSAGES
debug3: /etc/ssh/sshd_config:133 setting AcceptEnv LC_PAPER LC_NAME LC_ADDRESS LC_TELEPHONE LC_MEASUREMENT
debug3: /etc/ssh/sshd_config:134 setting AcceptEnv LC_IDENTIFICATION LC_ALL LANGUAGE
debug3: /etc/ssh/sshd_config:135 setting AcceptEnv XMODIFIERS
debug3: /etc/ssh/sshd_config:138 setting Subsystem sftp /usr/libexec/openssh/sftp-server
debug1: sshd version OpenSSH_8.0, OpenSSL 1.1.1k FIPS 25 Mar 2021
debug1: private host key #0: ssh-rsa SHA256:GwaDpWqZk3FQrfNmD4GqWDEcd1zur+dXZsbArmzrcGs
debug1: private host key #1: ecdsa-sha2-nistp256 SHA256:3aAAv+pS/mxSCadlScgN8CD6bclzSfzyZ5re9Cb30h0
debug1: private host key #2: ssh-ed25519 SHA256:7lS8fhUowMoIC8/5DJ0k62I6fzK1eA5PTClqFR0g4HM
debug1: rexec_argv[0]='/usr/sbin/sshd'
debug1: rexec_argv[1]='-ddd'
debug1: rexec_argv[2]='-E'
debug1: rexec_argv[3]='/tmp/ssh.log'
debug3: oom_adjust_setup
debug1: Set /proc/self/oom_score_adj from 0 to -1000
debug2: fd 4 setting O_NONBLOCK
debug1: Bind to port 22 on 0.0.0.0.
Server listening on 0.0.0.0 port 22.
debug2: fd 5 setting O_NONBLOCK
debug3: sock_set_v6only: set socket 5 IPV6_V6ONLY
debug1: Bind to port 22 on ::.
Server listening on :: port 22.
debug2: load_server_config: filename /etc/ssh/sshd_config
debug2: load_server_config: done config len = 734
debug2: parse_server_config_depth: config /etc/ssh/sshd_config len 734
debug3: /etc/ssh/sshd_config:22 setting HostKey /etc/ssh/ssh_host_rsa_key
debug3: /etc/ssh/sshd_config:23 setting HostKey /etc/ssh/ssh_host_ecdsa_key
debug3: /etc/ssh/sshd_config:24 setting HostKey /etc/ssh/ssh_host_ed25519_key
debug3: /etc/ssh/sshd_config:37 setting SyslogFacility AUTHPRIV
debug3: /etc/ssh/sshd_config:43 setting PermitRootLogin yes
debug3: /etc/ssh/sshd_config:52 setting AuthorizedKeysFile .ssh/authorized_keys
debug3: /etc/ssh/sshd_config:70 setting PasswordAuthentication yes
debug3: /etc/ssh/sshd_config:74 setting ChallengeResponseAuthentication no
debug3: /etc/ssh/sshd_config:84 setting GSSAPIAuthentication yes
debug3: /etc/ssh/sshd_config:85 setting GSSAPICleanupCredentials no
debug3: /etc/ssh/sshd_config:101 setting UsePAM yes
debug3: /etc/ssh/sshd_config:106 setting X11Forwarding yes
debug3: /etc/ssh/sshd_config:113 setting PrintMotd no
debug3: /etc/ssh/sshd_config:132 setting AcceptEnv LANG LC_CTYPE LC_NUMERIC LC_TIME LC_COLLATE LC_MONETARY LC_MESSAGES
debug3: /etc/ssh/sshd_config:133 setting AcceptEnv LC_PAPER LC_NAME LC_ADDRESS LC_TELEPHONE LC_MEASUREMENT
debug3: /etc/ssh/sshd_config:134 setting AcceptEnv LC_IDENTIFICATION LC_ALL LANGUAGE
debug3: /etc/ssh/sshd_config:135 setting AcceptEnv XMODIFIERS
debug3: /etc/ssh/sshd_config:138 setting Subsystem sftp /usr/libexec/openssh/sftp-server
debug1: sshd version OpenSSH_8.0, OpenSSL 1.1.1k FIPS 25 Mar 2021
debug1: private host key #0: ssh-rsa SHA256:GwaDpWqZk3FQrfNmD4GqWDEcd1zur+dXZsbArmzrcGs
debug1: private host key #1: ecdsa-sha2-nistp256 SHA256:3aAAv+pS/mxSCadlScgN8CD6bclzSfzyZ5re9Cb30h0
debug1: private host key #2: ssh-ed25519 SHA256:7lS8fhUowMoIC8/5DJ0k62I6fzK1eA5PTClqFR0g4HM
debug1: rexec_argv[0]='/usr/sbin/sshd'
debug1: rexec_argv[1]='-ddd'
debug1: rexec_argv[2]='-E'
debug1: rexec_argv[3]='/tmp/ssh.log'
debug3: oom_adjust_setup
debug1: Set /proc/self/oom_score_adj from 0 to -1000
debug2: fd 4 setting O_NONBLOCK
debug1: Bind to port 22 on 0.0.0.0.
Server listening on 0.0.0.0 port 22.
debug2: fd 5 setting O_NONBLOCK
debug3: sock_set_v6only: set socket 5 IPV6_V6ONLY
debug1: Bind to port 22 on ::.
Server listening on :: port 22.
debug3: fd 6 is not O_NONBLOCK
debug1: Server will not fork when running in debugging mode.
debug3: send_rexec_state: entering fd = 9 config len 734
debug3: ssh_msg_send: type 0
debug3: send_rexec_state: done
debug1: rexec start in 6 out 6 newsock 6 pipe -1 sock 9
debug3: recv_rexec_state: entering fd = 5
debug3: ssh_msg_recv entering
debug3: recv_rexec_state: done
debug2: parse_server_config_depth: config rexec len 734
debug3: rexec:22 setting HostKey /etc/ssh/ssh_host_rsa_key
debug3: rexec:23 setting HostKey /etc/ssh/ssh_host_ecdsa_key
debug3: rexec:24 setting HostKey /etc/ssh/ssh_host_ed25519_key
debug3: rexec:37 setting SyslogFacility AUTHPRIV
debug3: rexec:43 setting PermitRootLogin yes
debug3: rexec:52 setting AuthorizedKeysFile .ssh/authorized_keys
debug3: rexec:70 setting PasswordAuthentication yes
debug3: rexec:74 setting ChallengeResponseAuthentication no
debug3: rexec:84 setting GSSAPIAuthentication yes
debug3: rexec:85 setting GSSAPICleanupCredentials no
debug3: rexec:101 setting UsePAM yes
debug3: rexec:106 setting X11Forwarding yes
debug3: rexec:113 setting PrintMotd no
debug3: rexec:132 setting AcceptEnv LANG LC_CTYPE LC_NUMERIC LC_TIME LC_COLLATE LC_MONETARY LC_MESSAGES
debug3: rexec:133 setting AcceptEnv LC_PAPER LC_NAME LC_ADDRESS LC_TELEPHONE LC_MEASUREMENT
debug3: rexec:134 setting AcceptEnv LC_IDENTIFICATION LC_ALL LANGUAGE
debug3: rexec:135 setting AcceptEnv XMODIFIERS
debug3: rexec:138 setting Subsystem sftp /usr/libexec/openssh/sftp-server
debug1: sshd version OpenSSH_8.0, OpenSSL 1.1.1k FIPS 25 Mar 2021
debug1: private host key #0: ssh-rsa SHA256:GwaDpWqZk3FQrfNmD4GqWDEcd1zur+dXZsbArmzrcGs
debug1: private host key #1: ecdsa-sha2-nistp256 SHA256:3aAAv+pS/mxSCadlScgN8CD6bclzSfzyZ5re9Cb30h0
debug1: private host key #2: ssh-ed25519 SHA256:7lS8fhUowMoIC8/5DJ0k62I6fzK1eA5PTClqFR0g4HM
debug1: inetd sockets after dupping: 5, 5
Connection from ::1 port 56500 on ::1 port 22
debug1: Local version string SSH-2.0-OpenSSH_8.0
debug1: Remote protocol version 2.0, remote software version OpenSSH_8.0
debug1: match: OpenSSH_8.0 pat OpenSSH* compat 0x04000000
debug2: fd 5 setting O_NONBLOCK
debug3: ssh_sandbox_init: preparing seccomp filter sandbox
debug2: Network child is on pid 8363
debug3: preauth child monitor started
debug1: SELinux support enabled [preauth]
debug1: ssh_selinux_change_context: setting context from 'unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023' to 'unconfined_u:unconfined_r:sshd_net_t:s0-s0:c0.c1023' [preauth]
debug3: ssh_selinux_change_context: setcon unconfined_u:unconfined_r:sshd_net_t:s0-s0:c0.c1023 from unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 failed with Invalid argument [preauth]
debug3: privsep user:group 74:74 [preauth]
debug1: permanently_set_uid: 74/74 [preauth]
debug3: ssh_sandbox_child: setting PR_SET_NO_NEW_PRIVS [preauth]
debug3: ssh_sandbox_child: attaching seccomp filter program [preauth]
debug1: list_hostkey_types: rsa-sha2-512,rsa-sha2-256,ssh-rsa,ecdsa-sha2-nistp256,ssh-ed25519 [preauth]
debug3: send packet: type 20 [preauth]
debug1: SSH2_MSG_KEXINIT sent [preauth]
debug3: receive packet: type 20 [preauth]
debug1: SSH2_MSG_KEXINIT received [preauth]
debug2: local server KEXINIT proposal [preauth]
debug2: KEX algorithms: curve25519-sha256,[email protected],ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group14-sha256,diffie-hellman-group14-sha1 [preauth]
debug2: host key algorithms: rsa-sha2-512,rsa-sha2-256,ssh-rsa,ecdsa-sha2-nistp256,ssh-ed25519 [preauth]
debug2: ciphers ctos: [email protected],aes128-ctr,aes192-ctr,aes256-ctr,[email protected],[email protected] [preauth]
debug2: ciphers stoc: [email protected],aes128-ctr,aes192-ctr,aes256-ctr,[email protected],[email protected] [preauth]
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 [preauth]
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 [preauth]
debug2: compression ctos: none,[email protected] [preauth]
debug2: compression stoc: none,[email protected] [preauth]
debug2: languages ctos: [preauth]
debug2: languages stoc: [preauth]
debug2: first_kex_follows 0 [preauth]
debug2: reserved 0 [preauth]
debug2: peer client KEXINIT proposal [preauth]
debug2: KEX algorithms: curve25519-sha256,[email protected],ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,ext-info-c [preauth]
debug2: host key algorithms: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,ssh-ed25519,rsa-sha2-512,rsa-sha2-256,ssh-rsa [preauth]
debug2: ciphers ctos: [email protected],[email protected],aes256-ctr,aes256-cbc,[email protected],aes128-ctr,aes128-cbc [preauth]
debug2: ciphers stoc: [email protected],[email protected],aes256-ctr,aes256-cbc,[email protected],aes128-ctr,aes128-cbc [preauth]
debug2: MACs ctos: [email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha1,[email protected],hmac-sha2-512 [preauth]
debug2: MACs stoc: [email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha1,[email protected],hmac-sha2-512 [preauth]
debug2: compression ctos: none,[email protected],zlib [preauth]
debug2: compression stoc: none,[email protected],zlib [preauth]
debug2: languages ctos: [preauth]
debug2: languages stoc: [preauth]
debug2: first_kex_follows 0 [preauth]
debug2: reserved 0 [preauth]
debug1: kex: algorithm: curve25519-sha256 [preauth]
debug1: kex: host key algorithm: ecdsa-sha2-nistp256 [preauth]
debug1: kex: client->server cipher: [email protected] MAC: <implicit> compression: none [preauth]
debug1: kex: server->client cipher: [email protected] MAC: <implicit> compression: none [preauth]
debug1: kex: curve25519-sha256 need=32 dh_need=32 [preauth]
debug3: mm_request_send entering: type 120 [preauth]
debug3: mm_request_receive_expect entering: type 121 [preauth]
debug3: mm_request_receive entering [preauth]
debug3: mm_request_receive entering
debug3: monitor_read: checking request 120
debug3: mm_request_send entering: type 121
debug1: kex: curve25519-sha256 need=32 dh_need=32 [preauth]
debug3: mm_request_send entering: type 120 [preauth]
debug3: mm_request_receive_expect entering: type 121 [preauth]
debug3: mm_request_receive entering [preauth]
debug3: mm_request_receive entering
debug3: monitor_read: checking request 120
debug3: mm_request_send entering: type 121
debug1: expecting SSH2_MSG_KEX_ECDH_INIT [preauth]
debug3: receive packet: type 30 [preauth]
debug3: mm_sshkey_sign entering [preauth]
debug3: mm_request_send entering: type 6 [preauth]
debug3: mm_sshkey_sign: waiting for MONITOR_ANS_SIGN [preauth]
debug3: mm_request_receive_expect entering: type 7 [preauth]
debug3: mm_request_receive entering [preauth]
debug3: mm_request_receive entering
debug3: monitor_read: checking request 6
debug3: mm_answer_sign
debug3: mm_answer_sign: hostkey proof signature 0x55639ba6a250(101)
debug3: mm_request_send entering: type 7
debug2: monitor_read: 6 used once, disabling now
debug3: send packet: type 31 [preauth]
debug3: send packet: type 21 [preauth]
debug2: set_newkeys: mode 1 [preauth]
debug1: rekey out after 4294967296 blocks [preauth]
debug1: SSH2_MSG_NEWKEYS sent [preauth]
debug1: expecting SSH2_MSG_NEWKEYS [preauth]
debug3: send packet: type 7 [preauth]
debug3: receive packet: type 21 [preauth]
debug1: SSH2_MSG_NEWKEYS received [preauth]
debug2: set_newkeys: mode 0 [preauth]
debug1: rekey in after 4294967296 blocks [preauth]
debug1: KEX done [preauth]
debug3: receive packet: type 5 [preauth]
debug3: send packet: type 6 [preauth]
debug3: receive packet: type 50 [preauth]
debug1: userauth-request for user root service ssh-connection method none [preauth]
debug1: attempt 0 failures 0 [preauth]
debug3: mm_getpwnamallow entering [preauth]
debug3: mm_request_send entering: type 8 [preauth]
debug3: mm_getpwnamallow: waiting for MONITOR_ANS_PWNAM [preauth]
debug3: mm_request_receive_expect entering: type 9 [preauth]
debug3: mm_request_receive entering [preauth]
debug3: mm_request_receive entering
debug3: monitor_read: checking request 8
debug3: mm_answer_pwnamallow
debug2: parse_server_config_depth: config reprocess config len 734
debug3: mm_answer_pwnamallow: sending MONITOR_ANS_PWNAM: 1
debug3: mm_request_send entering: type 9
debug2: monitor_read: 8 used once, disabling now
debug2: input_userauth_request: setting up authctxt for root [preauth]
debug3: mm_start_pam entering [preauth]
debug3: mm_request_send entering: type 100 [preauth]
debug3: mm_inform_authserv entering [preauth]
debug3: mm_request_send entering: type 4 [preauth]
debug3: mm_inform_authrole entering [preauth]
debug3: mm_request_send entering: type 80 [preauth]
debug2: input_userauth_request: try method none [preauth]
debug3: mm_request_receive entering
debug3: monitor_read: checking request 100
debug1: PAM: initializing for "root"
debug1: PAM: setting PAM_RHOST to "::1"
debug1: PAM: setting PAM_TTY to "ssh"
debug2: monitor_read: 100 used once, disabling now
debug3: user_specific_delay: user specific delay 0.000ms [preauth]
debug3: ensure_minimum_time_since: elapsed 1.235ms, delaying 4.731ms (requested 5.966ms) [preauth]
debug1: monitor_read_log: child log fd closed
debug3: mm_request_receive entering
debug3: monitor_read: checking request 4
debug3: mm_answer_authserv: service=ssh-connection, style=
debug2: monitor_read: 4 used once, disabling now
debug3: mm_request_receive entering
debug3: monitor_read: checking request 80
debug3: mm_answer_authrole: role=
debug2: monitor_read: 80 used once, disabling now
debug3: mm_request_receive entering
debug1: do_cleanup
debug1: PAM: cleanup
debug3: PAM: sshpam_thread_cleanup entering
debug1: Killing privsep child 8363
有趣的是，如果我在 serverA 上运行 nmap，我还会看到以下内容：
Host is up (0.00013s latency).
PORT STATE SERVICE
22/tcp open ssh
| ssh-auth-methods:
|_ Supported authentication methods: false
尝试使用 PreferredAuthentications=passwrod 和 PubkeyAuthentication=no 进行 ssh 会产生相同的结果。
/etc/ssh/ssh_config 的副本
# $OpenBSD: ssh_config,v 1.34 2019/02/04 02:39:42 dtucker Exp $
# This is the ssh client system-wide configuration file. See
# ssh_config(5) for more information. This file provides defaults for
# users, and the values can be changed in per-user configuration files
# or on the command line.
# Configuration data is parsed as follows:
# 1. command line options
# 2. user-specific file
# 3. system-wide file
# Any configuration value is only changed the first time it is set.
# Thus, host-specific definitions should be at the beginning of the
# configuration file, and defaults at the end.
# Site-wide defaults for some commonly used options. For a comprehensive
# list of available options, their meanings and defaults, please see the
# ssh_config(5) man page.
# Host *
# ForwardAgent no
# ForwardX11 no
# PasswordAuthentication yes
# HostbasedAuthentication no
# GSSAPIAuthentication no
# GSSAPIDelegateCredentials no
# GSSAPIKeyExchange no
# GSSAPITrustDNS no
# BatchMode no
# CheckHostIP yes
# AddressFamily any
# ConnectTimeout 0
# StrictHostKeyChecking ask
# IdentityFile ~/.ssh/id_rsa
# IdentityFile ~/.ssh/id_dsa
# IdentityFile ~/.ssh/id_ecdsa
# IdentityFile ~/.ssh/id_ed25519
# Port 22
# Ciphers aes128-ctr,aes192-ctr,aes256-ctr,aes128-cbc,3des-cbc
# MACs hmac-md5,hmac-sha1,[email protected]
# EscapeChar ~
# Tunnel no
# TunnelDevice any:any
# PermitLocalCommand no
# VisualHostKey no
# ProxyCommand ssh -q -W %h:%p gateway.example.com
# RekeyLimit 1G 1h
#
# This system is following system-wide crypto policy.
# To modify the system-wide ssh configuration, create a *.conf file under
# /etc/ssh/ssh_config.d/ which will be automatically included below
Include /etc/ssh/ssh_config.d/*.conf
/etc/ssh/sshd_config 的副本
# $OpenBSD: sshd_config,v 1.103 2018/04/09 20:41:22 tj Exp $
# This is the sshd server system-wide configuration file. See
# sshd_config(5) for more information.
# This sshd was compiled with PATH=/usr/local/bin:/usr/bin:/usr/local/sbin:/usr/sbin
# The strategy used for options in the default sshd_config shipped with
# OpenSSH is to specify options with their default value where
# possible, but leave them commented. Uncommented options override the
# default value.
# If you want to change the port on a SELinux system, you have to tell
# SELinux about this change.
# semanage port -a -t ssh_port_t -p tcp #PORTNUMBER
#
#Port 22
#AddressFamily any
#ListenAddress 0.0.0.0
#ListenAddress ::
HostKey /etc/ssh/ssh_host_rsa_key
HostKey /etc/ssh/ssh_host_ecdsa_key
HostKey /etc/ssh/ssh_host_ed25519_key
# Ciphers and keying
#RekeyLimit default none
# This system is following system-wide crypto policy. The changes to
# crypto properties (Ciphers, MACs, ...) will not have any effect here.
# They will be overridden by command-line options passed to the server
# on command line.
# Please, check manual pages for update-crypto-policies(8) and sshd_config(5).
# Logging
#SyslogFacility AUTH
SyslogFacility AUTHPRIV
#LogLevel INFO
# Authentication:
#LoginGraceTime 2m
PermitRootLogin yes
#StrictModes yes
#MaxAuthTries 6
#MaxSessions 10
#PubkeyAuthentication yes
# The default is to check both .ssh/authorized_keys and .ssh/authorized_keys2
# but this is overridden so installations will only check .ssh/authorized_keys
AuthorizedKeysFile .ssh/authorized_keys
#AuthorizedPrincipalsFile none
#AuthorizedKeysCommand none
#AuthorizedKeysCommandUser nobody
# For this to work you will also need host keys in /etc/ssh/ssh_known_hosts
#HostbasedAuthentication no
# Change to yes if you don't trust ~/.ssh/known_hosts for
# HostbasedAuthentication
#IgnoreUserKnownHosts no
# Don't read the user's ~/.rhosts and ~/.shosts files
#IgnoreRhosts yes
# To disable tunneled clear text passwords, change to no here!
#PasswordAuthentication yes
#PermitEmptyPasswords no
PasswordAuthentication yes
# Change to no to disable s/key passwords
#ChallengeResponseAuthentication yes
ChallengeResponseAuthentication no
# Kerberos options
#KerberosAuthentication no
#KerberosOrLocalPasswd yes
#KerberosTicketCleanup yes
#KerberosGetAFSToken no
#KerberosUseKuserok yes
# GSSAPI options
GSSAPIAuthentication yes
GSSAPICleanupCredentials no
#GSSAPIStrictAcceptorCheck yes
#GSSAPIKeyExchange no
#GSSAPIEnablek5users no
# 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'.
# WARNING: 'UsePAM no' is not supported in RHEL and may cause several
# problems.
UsePAM yes
#AllowAgentForwarding yes
#AllowTcpForwarding yes
#GatewayPorts no
X11Forwarding yes
#X11DisplayOffset 10
#X11UseLocalhost yes
#PermitTTY yes
# It is recommended to use pam_motd in /etc/pam.d/sshd instead of PrintMotd,
# as it is more configurable and versatile than the built-in version.
PrintMotd no
#PrintLastLog yes
#TCPKeepAlive yes
#PermitUserEnvironment no
#Compression delayed
#ClientAliveInterval 0
#ClientAliveCountMax 3
#UseDNS no
#PidFile /var/run/sshd.pid
#MaxStartups 10:30:100
#PermitTunnel no
#ChrootDirectory none
#VersionAddendum none
# no default banner path
#Banner none
# Accept locale-related environment variables
AcceptEnv LANG LC_CTYPE LC_NUMERIC LC_TIME LC_COLLATE LC_MONETARY LC_MESSAGES
AcceptEnv LC_PAPER LC_NAME LC_ADDRESS LC_TELEPHONE LC_MEASUREMENT
AcceptEnv LC_IDENTIFICATION LC_ALL LANGUAGE
AcceptEnv XMODIFIERS
# override default of no subsystems
Subsystem sftp /usr/libexec/openssh/sftp-server
# Example of overriding settings on a per-user basis
#Match User anoncvs
# X11Forwarding no
# AllowTcpForwarding no
# PermitTTY no
# ForceCommand cvs server
我不确定到底发生了什么变化 - 内部防火墙的流量没有变化。yum 历史记录中没有任何内容表明有任何更新，我能够与其他服务器正常 ssh 连接。我觉得这就像有什么盲目的东西盯着我 - 我在这里错过了什么？
答案1
- 你写：
/etch/sshd_config 设置为允许 PasswordAuthentication
（你显然指的是文件/etc/ssh/sshd_config）
但结果
userauth-request for user root service ssh-connection method none
=> 这些说法是矛盾的。
- 您声明服务器日志中没有条目。
=> 这与上面的消息一致ssh-connection method none。没有连接方法不是一个错误，而是一种配置状态。
*结果是 ssh 服务器上没有配置身份验证方法。因此无法进行身份验证，登录通信会在之前以常规断开连接结束 *
否则，我们会在您的调试日志中的该位置看到类似这样的消息，而不是Connection closed by serverA port 22：
debug1: Next authentication method: password
因此，查找错误的第一件事就是查看 ssh-server 配置
/etc/ssh/sshd_config
不幸的是，您打算粘贴该文件，但结果却不是这样/etc/ssh/ssh_config（没有d后面的ssh）
由于您不知道禁用密码验证，我认为肯定是输入错误，即您不小心删除了评论#（或者第三方确实更改了sshd_config）。
请搜索文件
PasswordAuthentication
- 确保此条目的值设置为
yes并且未被注释#：
PasswordAuthentication yes
这应该是默认的，但编译的默认值也可以更改......
检查整个文件以查找更多关键字条目并禁用或删除它们。
更改后
sshd_config必须重新启动 sshd：
systemctl restart sshd
- 此外，如果您没有更改任何内容，请重新启动，
sshd因为已经应用的测试更改可能尚未被重新读取sshd（通过重新启动）。
如果错误仍然存在，您应该根据实际情况更新您的问题，/etc/ssh/sshd_config以便我们查看。