在本文中，我们将向您展示如何在Linux中运行SSH时打开调试模式。 这将使您能够看到执行ssh命令以使用详细模式或调试模式连接到远程Linux服务器时实际展开的内容。
另请参阅 ： 在Linux中加速SSH连接的4种方法
ssh客户端的-v开关允许您以详细模式运行ssh，打印有关SSH连接进度的调试信息，这对于调试连接，验证和任何配置问题非常有用。 有不同程度的冗长; 使用多个-v标志会增加冗长度（最大冗余级别为3）。
以下命令将在第一级别冗长的情况下运行SSH，这将给我们提供大量的调试信息，如图所示。
[email protected] ~ $ ssh -v [email protected]
示例输出
OpenSSH_7.2p2 Ubuntu-4ubuntu2.2, OpenSSL 1.0.2g-fips 1 Mar 2016 debug1: Reading configuration data /home/aaronkilik/.ssh/config debug1: /home/aaronkilik/.ssh/config line 18: Applying options for * debug1: Reading configuration data /etc/ssh/ssh_config debug1: /etc/ssh/ssh_config line 19: Applying options for * debug1: Connecting to 192.168.56.10 [192.168.56.10] port 22. debug1: Connection established. debug1: identity file /home/aaronkilik/.ssh/id_rsa type 1 debug1: key_load_public: No such file or directory debug1: identity file /home/aaronkilik/.ssh/id_rsa-cert type -1 debug1: key_load_public: No such file or directory debug1: identity file /home/aaronkilik/.ssh/id_dsa type -1 debug1: key_load_public: No such file or directory debug1: identity file /home/aaronkilik/.ssh/id_dsa-cert type -1 debug1: key_load_public: No such file or directory debug1: identity file /home/aaronkilik/.ssh/id_ecdsa type -1 debug1: key_load_public: No such file or directory debug1: identity file /home/aaronkilik/.ssh/id_ecdsa-cert type -1 debug1: key_load_public: No such file or directory debug1: identity file /home/aaronkilik/.ssh/id_ed25519 type -1 debug1: key_load_public: No such file or directory debug1: identity file /home/aaronkilik/.ssh/id_ed25519-cert type -1 debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_7.2p2 Ubuntu-4ubuntu2.2 debug1: Remote protocol version 2.0, remote software version OpenSSH_7.4 debug1: match: OpenSSH_7.4 pat OpenSSH* compat 0x04000000 debug1: Authenticating to 192.168.56.10:22 as 'youcl' debug1: SSH2_MSG_KEXINIT sent debug1: SSH2_MSG_KEXINIT received debug1: kex: algorithm: [email protected] debug1: kex: host key algorithm: ecdsa-sha2-nistp256 debug1: kex: server->client cipher: [email protected] MAC: compression: [email protected] debug1: kex: client->server cipher: [email protected] MAC: compression: [email protected] debug1: expecting SSH2_MSG_KEX_ECDH_REPLY debug1: Server host key: ecdsa-sha2-nistp256 SHA256:1778erqyug4tHJa7D6y/Ep4UWsUtNEOBSMaj32k9oO8 debug1: Host '192.168.56.10' is known and matches the ECDSA host key. debug1: Found key in /home/aaronkilik/.ssh/known_hosts:8 debug1: rekey after 134217728 blocks debug1: SSH2_MSG_NEWKEYS sent debug1: expecting SSH2_MSG_NEWKEYS debug1: rekey after 134217728 blocks debug1: SSH2_MSG_NEWKEYS received debug1: SSH2_MSG_EXT_INFO received debug1: kex_input_ext_info: server-sig-algs=<rsa-sha2-256,rsa-sha2-512> debug1: SSH2_MSG_SERVICE_ACCEPT received debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password debug1: Next authentication method: publickey debug1: Offering RSA public key: /home/aaronkilik/.ssh/id_rsa debug1: Server accepts key: pkalg rsa-sha2-512 blen 279 debug1: Enabling compression at level 6. debug1: Authentication succeeded (publickey). Authenticated to 192.168.56.10 ([192.168.56.10]:22). debug1: channel 0: new [client-session] debug1: Requesting [email protected] debug1: Entering interactive session. debug1: pledge: network debug1: client_input_global_request: rtype [email protected] want_reply 0 debug1: Sending environment. debug1: Sending env LC_PAPER = lg_UG.UTF-8 debug1: Sending env LC_ADDRESS = lg_UG.UTF-8 debug1: Sending env LC_MONETARY = lg_UG.UTF-8 debug1: Sending env LC_NUMERIC = lg_UG.UTF-8 debug1: Sending env LC_TELEPHONE = lg_UG.UTF-8 debug1: Sending env LC_IDENTIFICATION = lg_UG.UTF-8 debug1: Sending env LANG = en_US.UTF-8 debug1: Sending env LC_MEASUREMENT = lg_UG.UTF-8 debug1: Sending env LC_NAME = lg_UG.UTF-8 Last login: Sat Jan 6 16:20:11 2018 from 192.168.56.1
尝试注销或退出会话时，您还将看到如图所示的调试消息。
[[email protected] ~]$ exit logout debug1: client_input_channel_req: channel 0 rtype exit-status reply 0 debug1: client_input_channel_req: channel 0 rtype [email protected] reply 0 debug1: channel 0: free: client-session, nchannels 1 Connection to 192.168.56.10 closed. Transferred: sent 3392, received 3120 bytes, in 118.1 seconds Bytes per second: sent 28.7, received 26.4 debug1: Exit status 0 debug1: compress outgoing: raw data 1159, compressed 573, factor 0.49 debug1: compress incoming: raw data 573, compressed 1159, factor 2.02
接下来，您可以为更多的调试消息启用额外的（2级和3级）详细信息，如图所示。
$ ssh -vv [email protected] $ ssh -vvv [email protected]
而已！ 有关SSH的更多用法，请阅读以下相关文章。
我们希望您觉得这篇文章有用。 您可以通过下面的评论表格询问任何问题或分享想法。
