近期经常遇到ssh登录问题，不是卡顿就是拒绝，还有无法登录认证问题（新建用户可以登录，或权限太大无法登录）等，搞得焦头烂额，以下汇总整理，并继续更新中。
先看下正常登录详情：
[monitor00@~]$ssh -v [email protected]
OpenSSH_7.4p1, OpenSSL 1.0.2k-fips 26 Jan 2017
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 58: Applying options for *
debug1: Connecting to 172.16.19.23 [172.16.19.23] port 22.
debug1: Connection established.
debug1: key_load_public: No such file or directory
debug1: identity file /home/cscroot/.ssh/id_rsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/cscroot/.ssh/id_rsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/cscroot/.ssh/id_dsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/cscroot/.ssh/id_dsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/cscroot/.ssh/id_ecdsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/cscroot/.ssh/id_ecdsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/cscroot/.ssh/id_ed25519 type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/cscroot/.ssh/id_ed25519-cert type -1
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_7.4
debug1: Remote protocol version 2.0, remote software version OpenSSH_5.3
debug1: match: OpenSSH_5.3 pat OpenSSH_5* compat 0x0c000000
debug1: Authenticating to 172.16.19.23:22 as 'root'
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: algorithm: diffie-hellman-group-exchange-sha256
debug1: kex: host key algorithm: ssh-rsa
debug1: kex: server->client cipher: aes128-ctr MAC: [email protected] compression: none
debug1: kex: client->server cipher: aes128-ctr MAC: [email protected] compression: none
debug1: kex: diffie-hellman-group-exchange-sha256 need=16 dh_need=16
debug1: kex: diffie-hellman-group-exchange-sha256 need=16 dh_need=16
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<3072<8192) sent
debug1: got SSH2_MSG_KEX_DH_GEX_GROUP
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: got SSH2_MSG_KEX_DH_GEX_REPLY
debug1: Server host key: ssh-rsa SHA256:oR73znvjJ110Pjr8R99K3QeIAHqovMOX0FZGTrhdn9o
debug1: Host '172.16.19.23' is known and matches the RSA host key.
debug1: Found key in /home/cscroot/.ssh/known_hosts:517
debug1: rekey after 4294967296 blocks
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: rekey after 4294967296 blocks
debug1: SSH2_MSG_SERVICE_ACCEPT received
'debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password
debug1: Next authentication method: gssapi-keyex
debug1: No valid Key exchange context
debug1: Next authentication method: gssapi-with-mic
debug1: Unspecified GSS failure. Minor code may provide more information
No Kerberos credentials available (default cache: KEYRING:persistent:1000)
debug1: Unspecified GSS failure. Minor code may provide more information
No Kerberos credentials available (default cache: KEYRING:persistent:1000)
'
debug1: Next authentication method: publickey
debug1: Trying private key: /home/cscroot/.ssh/id_rsa
debug1: Trying private key: /home/cscroot/.ssh/id_dsa
debug1: Trying private key: /home/cscroot/.ssh/id_ecdsa
debug1: Trying private key: /home/cscroot/.ssh/id_ed25519
debug1: Next authentication method: password
[email protected]'s password:
debug1: Authentication succeeded (password).
Authenticated to 172.16.19.23 ([172.16.19.23]:22).
debug1: channel 0: new [client-session]
debug1: Requesting [email protected]
debug1: Entering interactive session.
debug1: pledge: network
debug1: Sending environment.
debug1: Sending env LANG = en_US.UTF-8
Last login: Wed Aug 2 10:04:49 2023 from 172.16.19.731、ssh登录过程中卡，或输入密码后无反应
首先排除掉网络问题，可以通过ping看看是否存在高延迟，建议在内网同网段地址间测试，因同网段内延迟都小于1；
其次测试ssh服务端口处于监听状态，可以通过telnet命令测试，观察是否卡；
再次
2、拒绝登录
3、权限太大无法登录
4、输入密码后快速回退到重新登录界面