首先，想说句脏话，差，你害得我好苦啊。
最近在搞linux，发现每次登录都要输入用户名密码好麻烦，于是就想起了大学里面对的RSA对称加密生成密钥对登录linux系统。
1.用root身份登录新建一个账户（这里一隐藏了一个想死人bug，都是linux权限还不熟悉啊）
useradd git
passwd git 123456
2.修改sshd_config
vi /etc/ssh/ssh_cnfig（这里就不一个一个说了，直接上修改后的代码）
#$OpenBSD: sshd_config,v 1.80 2008/07/02 02:24:18 djm 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:/bin:/usr/bin
# 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 change a
# default value.
#Port 22
#AddressFamily any
#ListenAddress 0.0.0.0
#ListenAddress ::
# Disable legacy (protocol version 1) support in the server for new
# installations. In future the default will change to require explicit
# activation of protocol 1
Protocol 2
# HostKey for protocol version 1
#HostKey /etc/ssh/ssh_host_key
# HostKeys for protocol version 2
#HostKey /etc/ssh/ssh_host_rsa_key
#HostKey /etc/ssh/ssh_host_dsa_key
# Lifetime and size of ephemeral version 1 server key
#KeyRegenerationInterval 1h
#ServerKeyBits 1024
# Logging
# obsoletes QuietMode and FascistLogging
#SyslogFacility AUTH
SyslogFacility AUTHPRIV
#LogLevel INFO
# Authentication:
#LoginGraceTime 2m
#PermitRootLogin yes
#StrictModes yes
#MaxAuthTries 6
#MaxSessions 10
RSAAuthentication yes
PubkeyAuthentication yes
AuthorizedKeysFile.ssh/authorized_keys
#AuthorizedKeysCommand none
#AuthorizedKeysCommandRunAs nobody
# For this to work you will also need host keys in /etc/ssh/ssh_known_hosts
#RhostsRSAAuthentication no
# similar for protocol version 2
#HostbasedAuthentication no
# Change to yes if you don't trust ~/.ssh/known_hosts for
# RhostsRSAAuthentication and 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 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 no
GSSAPIAuthentication yes
#GSSAPICleanupCredentials yes
GSSAPICleanupCredentials yes
#GSSAPIStrictAcceptorCheck yes
#GSSAPIKeyExchange 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'.
#UsePAM no
UsePAM yes
# 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
#AllowAgentForwarding yes
#AllowTcpForwarding yes
#GatewayPorts no
#X11Forwarding no
X11Forwarding yes
#X11DisplayOffset 10
#X11UseLocalhost yes
#PrintMotd yes
#PrintLastLog yes
#TCPKeepAlive yes
#UseLogin no
#UsePrivilegeSeparation yes
#PermitUserEnvironment no
#Compression delayed
#ClientAliveInterval 0
#ClientAliveCountMax 3
#ShowPatchLevel no
#UseDNS yes
#PidFile /var/run/sshd.pid
#MaxStartups 10
#PermitTunnel no
#ChrootDirectory none
# no default banner path
#Banner none
# override default of no subsystems
Subsystemsftp/usr/libexec/openssh/sftp-server
# Example of overriding settings on a per-user basis
#Match User anoncvs
#X11Forwarding no
#AllowTcpForwarding no
#ForceCommand cvs server
3.重启 /etc/init.d/sshd restart(方法几种，这里只说一种)
4.切换到git用户
su - git
5.生成密钥对
ssh-keygen -t rsa(一直enter，你也可以输入密钥的密码)
6.追加到.ssh/authorized_keys
echo `cat id_rsa.pub` >> authorized_keys
7.下载到windows
sz id_rsa id_rsa.pug
7.首先用putty登录（要想用putty登录必须要转换格式，否则是不行的，这里不解释为什么）
分别是保存公钥和私钥（注文件名想同后缀不同，放在同一目录下面）
8.利用putty登录（结果登录不上，让我找了一天的原因）
9.chmod 0700 .ssh chmod 0600 .ssh/authorized_keys
这样就可以了，否则一直报Server refused our key
10.工作中用putty的还是比较少，一直用securecrt登录，这个登录也是一样，只是用的是公钥（putty用的私钥，其实原理一样，只是各软件开发者，想法不一样），直接上图
还有其它登录也是一样的。
最后，如果大家想深入了解公私钥登录，请自己想相关文档，这里由于工作时间问题，就不一一介绍。在学习过程当中，一定要注意权限，我开始登录不是就是由于useradd增加用户账户的时候默认也给我组权限和文件权限设置不正确，还有要注意，putty支持的文件格式和securecrt文件格式和linux openssl文件的格式，否则容易搞混。结束，有问题你留言
