版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/SunnyYoona/article/details/51689041
1. 创建ssh-key
这里我们采用rsa方式，使用如下命令：
xiaosi@xiaosi:~$ ssh-keygen -t rsa -f ~/.ssh/id_rsaGenerating public/private rsa key pair.Created directory '/home/xiaosi/.ssh'.Enter passphrase (empty for no passphrase):Enter same passphrase again:Your identification has been saved in /home/xiaosi/.ssh/id_rsa.Your public key has been saved in /home/xiaosi/.ssh/id_rsa.pub.The key fingerprint is:SHA256:n/sFaAT94A/xxxxxxxxxxxxxxxxxxxxxxx xiaosi@xiaosiThe key's randomart image is:+---[xxxxx]----+| o= .. .. || o.= .. .|| *.* o .|| +.4.=E+..|| .SBo=. h+ || ogo..oo. || or +j..|| ...+o=.|| ... o=+|+----[xxxxx]-----+
备注：
这里会提示输入pass phrase，一定不要输入任何字符，回车即可。
2. 生成authorized_keys文件
xiaosi@xiaosi:~$ cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
备注：
记得要把authorized_keys文件放到.ssh目录下，与rsa等文件放在一起，否则免登录失败，debug如下（ssh -vvv localhost进行调试，查找错误原因）：
xiaosi@xiaosi:~$ ssh -vvv localhostOpenSSH_7.2p2 Ubuntu-4ubuntu1, OpenSSL 1.0.2g-fips 1 Mar 2016debug1: Reading configuration data /etc/ssh/ssh_configdebug1: /etc/ssh/ssh_config line 19: Applying options for *debug2: resolving "localhost" port 22debug2: ssh_connect_direct: needpriv 0debug1: Connecting to localhost [127.0.0.1] port 22.debug1: Connection established.debug1: identity file /home/xiaosi/.ssh/id_rsa type 1debug1: key_load_public: No such file or directorydebug1: identity file /home/xiaosi/.ssh/id_rsa-cert type -1debug1: key_load_public: No such file or directorydebug1: identity file /home/xiaosi/.ssh/id_dsa type -1debug1: key_load_public: No such file or directorydebug1: identity file /home/xiaosi/.ssh/id_dsa-cert type -1debug1: key_load_public: No such file or directorydebug1: identity file /home/xiaosi/.ssh/id_ecdsa type -1debug1: key_load_public: No such file or directorydebug1: identity file /home/xiaosi/.ssh/id_ecdsa-cert type -1debug1: key_load_public: No such file or directorydebug1: identity file /home/xiaosi/.ssh/id_ed25519 type -1debug1: key_load_public: No such file or directorydebug1: identity file /home/xiaosi/.ssh/id_ed25519-cert type -1debug1: Enabling compatibility mode for protocol 2.0debug1: Local version string SSH-2.0-OpenSSH_7.2p2 Ubuntu-4ubuntu1debug1: Remote protocol version 2.0, remote software version OpenSSH_7.2p2 Ubuntu-4ubuntu1debug1: match: OpenSSH_7.2p2 Ubuntu-4ubuntu1 pat OpenSSH* compat 0x04000000debug2: fd 3 setting O_NONBLOCKdebug1: Authenticating to localhost:22 as 'xiaosi'debug3: hostkeys_foreach: reading file "/home/xiaosi/.ssh/known_hosts"debug3: record_hostkey: found key type ECDSA in file /home/xiaosi/.ssh/known_hosts:1debug3: load_hostkeys: loaded 1 keys from localhostdebug3: order_hostkeyalgs: prefer hostkeyalgs: ecdsa-sha2-nistp256-cert-v01@openssh.com,ecdsa-sha2-nistp384-cert-v01@openssh.com,ecdsa-sha2-nistp521-cert-v01@openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521debug3: send packet: type 20debug1: SSH2_MSG_KEXINIT sentdebug3: receive packet: type 20debug1: SSH2_MSG_KEXINIT receiveddebug2: local client KEXINIT proposaldebug2: KEX algorithms: curve25519-sha256@libssh.org,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-cdebug2: host key algorithms: ecdsa-sha2-nistp256-cert-v01@openssh.com,ecdsa-sha2-nistp384-cert-v01@openssh.com,ecdsa-sha2-nistp521-cert-v01@openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,ssh-ed25519-cert-v01@openssh.com,ssh-rsa-cert-v01@openssh.com,ssh-ed25519,rsa-sha2-512,rsa-sha2-256,ssh-rsadebug2: ciphers ctos: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com,aes128-cbc,aes192-cbc,aes256-cbc,3des-cbcdebug2: ciphers stoc: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com,aes128-cbc,aes192-cbc,aes256-cbc,3des-cbcdebug2: 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-sha1debug2: 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-sha1debug2: compression ctos: none,zlib@openssh.com,zlibdebug2: compression stoc: none,zlib@openssh.com,zlibdebug2: languages ctos:debug2: languages stoc:debug2: first_kex_follows 0debug2: reserved 0debug2: peer server KEXINIT proposaldebug2: KEX algorithms: curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha1debug2: host key algorithms: ssh-rsa,rsa-sha2-512,rsa-sha2-256,ecdsa-sha2-nistp256,ssh-ed25519debug2: ciphers ctos: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.comdebug2: ciphers stoc: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.comdebug2: 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-sha1debug2: 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-sha1debug2: compression ctos: none,zlib@openssh.comdebug2: compression stoc: none,zlib@openssh.comdebug2: languages ctos:debug2: languages stoc:debug2: first_kex_follows 0debug2: reserved 0debug1: kex: algorithm: curve25519-sha256@libssh.orgdebug1: kex: host key algorithm: ecdsa-sha2-nistp256debug1: kex: server->client cipher: chacha20-poly1305@openssh.com MAC: <implicit> compression: nonedebug1: kex: client->server cipher: chacha20-poly1305@openssh.com MAC: <implicit> compression: nonedebug3: send packet: type 30debug1: expecting SSH2_MSG_KEX_ECDH_REPLYdebug3: receive packet: type 31debug1: Server host key: ecdsa-sha2-nistp256 SHA256:378enl3ckhdpObP8fnsHr1EXz4d1q2Jde+jUplkub/Ydebug3: hostkeys_foreach: reading file "/home/xiaosi/.ssh/known_hosts"debug3: record_hostkey: found key type ECDSA in file /home/xiaosi/.ssh/known_hosts:1debug3: load_hostkeys: loaded 1 keys from localhostdebug1: Host 'localhost' is known and matches the ECDSA host key.debug1: Found key in /home/xiaosi/.ssh/known_hosts:1debug3: send packet: type 21debug2: set_newkeys: mode 1debug1: rekey after 134217728 blocksdebug1: SSH2_MSG_NEWKEYS sentdebug1: expecting SSH2_MSG_NEWKEYSdebug3: receive packet: type 21debug2: set_newkeys: mode 0debug1: rekey after 134217728 blocksdebug1: SSH2_MSG_NEWKEYS receiveddebug2: key: /home/xiaosi/.ssh/id_rsa (0x5602df5e80c0)debug2: key: /home/xiaosi/.ssh/id_dsa ((nil))debug2: key: /home/xiaosi/.ssh/id_ecdsa ((nil))debug2: key: /home/xiaosi/.ssh/id_ed25519 ((nil))debug3: send packet: type 5debug3: receive packet: type 7debug1: SSH2_MSG_EXT_INFO receiveddebug1: kex_input_ext_info: server-sig-algs=<rsa-sha2-256,rsa-sha2-512>debug3: receive packet: type 6debug2: service_accept: ssh-userauthdebug1: SSH2_MSG_SERVICE_ACCEPT receiveddebug3: send packet: type 50debug3: receive packet: type 51debug1: Authentications that can continue: publickey,passworddebug3: start over, passed a different list publickey,passworddebug3: preferred gssapi-keyex,gssapi-with-mic,publickey,keyboard-interactive,passworddebug3: authmethod_lookup publickeydebug3: remaining preferred: keyboard-interactive,passworddebug3: authmethod_is_enabled publickeydebug1: Next authentication method: publickeydebug1: Offering RSA public key: /home/xiaosi/.ssh/id_rsadebug3: send_pubkey_testdebug3: send packet: type 50debug2: we sent a publickey packet, wait for replydebug3: receive packet: type 51debug1: Authentications that can continue: publickey,passworddebug1: Trying private key: /home/xiaosi/.ssh/id_dsadebug3: no such identity: /home/xiaosi/.ssh/id_dsa: No such file or directorydebug1: Trying private key: /home/xiaosi/.ssh/id_ecdsadebug3: no such identity: /home/xiaosi/.ssh/id_ecdsa: No such file or directorydebug1: Trying private key: /home/xiaosi/.ssh/id_ed25519debug3: no such identity: /home/xiaosi/.ssh/id_ed25519: No such file or directorydebug2: we did not send a packet, disable methoddebug3: authmethod_lookup passworddebug3: remaining preferred: ,passworddebug3: authmethod_is_enabled passworddebug1: Next authentication method: passwordxiaosi@localhost's password:
3. 验证
xiaosi@xiaosi:~$ ssh localhostThe authenticity of host 'localhost (127.0.0.1)' can't be established.ECDSA key fingerprint is SHA256:378enl3ckhdpObP8fnsHr1EXz4d1q2Jde+jUplkub/Y.Are you sure you want to continue connecting (yes/no)? yesWarning: Permanently added 'localhost' (ECDSA) to the list of known hosts.sign_and_send_pubkey: signing failed: agent refused operationxiaosi@localhost's password:
4. authorized_keys权限
我们可以看到还是让我输入密码，很大可能是authorized_keys文件权限的问题，我们给该文件赋予一定权限：
xiaosi@xiaosi:~$ chmod 600 ~/.ssh/authorized_keys
xiaosi@xiaosi:~$ ssh localhostWelcome to Ubuntu 16.04 LTS (GNU/Linux 4.4.0-24-generic x86_64)* Documentation: https://help.ubuntu.com/0 个可升级软件包。0 个安全更新。Last login: Thu Jun 16 08:05:50 2016 from 127.0.0.1
到此表示OK了。
备注：
或者第一次需要输入密码，以后再次登陆就不需要输入密码了。
有更明白的小伙伴可以指导一下。。。。。。
