模拟实验通过密钥免密码登录
服务端IP：39.105.28.110
客户端IP：120.92.211.10
1.首先在客户端创建密钥
-t 指定密钥类型，默认是 rsa ，可以省略。
-C 设置注释文字，比如邮箱。
-f 指定密钥文件存储文件名。
[root@liukai ~]#ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa): //回车
Enter passphrase (empty for no passphrase): //回车
Enter same passphrase again:
Your identification has been saved in /root/.ssh/id_rsa. //私钥生成位置
Your public key has been saved in /root/.ssh/id_rsa.pub. //公钥生成位置
The key fingerprint is:
SHA256:DffrB1rtctrvyfGiiB6E2kFNlQR7Je8O5wL7Zzsw5OQ root@liukai
The key's randomart image is:
+---[RSA 3072]----+
| o++.. |
| o ..+ |
| . + o . |
| . . =oo |
| o S=o +. |
| o o oE=o.. |
| . . o .=+o . |
| +.+=.* +|
| .o oo=O.*+|
+----[SHA256]-----+
[root@liukai .ssh]#cd .ssh/ //跳转到存放目录通过ls可以看到生成的密钥
[root@liukai .ssh]# ls
authorized_keys id_rsa id_rsa.pub known_hosts
2.将公钥上传到客户端
[root@liukai .ssh]# scp id_rsa.pub root@39.105.28.110: //通过scp拷贝至服务端用户根目录
root@39.105.28.140's password: //输入服务端密码3.在服务端查看ssh配置文件，方便后续配置。(星号部分为本次实验需要注意的)
[root@liukai ~]# cat /etc/ssh/sshd_config
# $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 //端口
#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
# System-wide Crypto policy:
# This system is following system-wide crypto policy. The changes to
# Ciphers, MACs, KexAlgoritms and GSSAPIKexAlgorithsm will not have any
# effect here. They will be overridden by command-line options passed on
# the server start up.
# To opt out, uncomment a line with redefinition of CRYPTO_POLICY=
# variable in /etc/sysconfig/sshd to overwrite the policy.
# For more information, see manual page for update-crypto-policies(8).
# Logging
#SyslogFacility AUTH
#LogLevel INFO
# Authentication:
#LoginGraceTime 2m
#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!
#PermitEmptyPasswords no
# 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
# 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
# and ChallengeResponseAuthentication to 'no'.
# WARNING: 'UsePAM no' is not supported in Fedora 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
UseDNS no
AddressFamily inet
SyslogFacility AUTHPRIV
**PermitRootLogin yes** //是否允许root登录
PasswordAuthentication yes
4.在用户目录下查看，公钥是否上传成功，将上传的公钥添加到authorized_keys中
[root@liukai ~]# ls
id_rsa.pub //上传成功
[root@liukai ~]# cat id_rsa.pub >>.ssh/authorized_keys //添加5.修改权限，并重启服务
[root@liukai ~]chmod 700 /root //权限可能导致无法免密码登录
[root@liukai ~]chmod 700 .sshd
[root@liukai ~]chmod 600 authorized_key
[root@liukai ~]service sshd restart6.在客户端测试测试
[root@liukai ~]# ssh root@39.105.28.110
Welcome to Alibaba Cloud Elastic Compute Service !
Activate the web console with: systemctl enable --now cockpit.socket
Last login: Sat Sep 5 15:37:53 2020 from 120.92.211.10
[root@liukai ~]#试验成功Yes