限制用户通过ssh密钥进行认证登陆

为了服务器和 用户 的安全，禁止 用户 密码的 认证 方式，而基于钥匙的方式。 Lastlogin:FriOct1214:14:012012from192.168.7.251 root@Cacti.Nagios:[/root] vi/etc/ssh/sshd_config #$OpenBSD:sshd_config,v1.802008/07/0202:24:18djmExp$ #Thisisthesshdse

为了服务器和用户的安全，禁止用户密码的认证方式，而基于“钥匙”的方式。

Last login: Fri Oct 12 14:14:01 2012 from 192.168.7.251 
root@Cacti.Nagios:[/root]vi /etc/ssh/sshd_config  
#       $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 ← 修改后变为此状态，仅使用SSH2
 
# 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 
PermitRootLogin no ← 修改后变为此状态，不允许用root进行登录
#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 
PasswordAuthentication no ← 修改后变为此状态，不允许密码方式的登录
#PermitEmptyPasswords no 
PermitEmptyPasswords no ← 修改后变为此状态，禁止空密码进行登录
"/etc/ssh/sshd_config" 141L, 3941C written                             
root@Cacti.Nagios:[/root]vi /etc/hosts.deny    ← 修改屏蔽规则，在文尾添加相应行
# 
# hosts.deny    This file contains access rules which are used to 
#               deny connections to network services that either use 
#               the tcp_wrappers library or that have been 
#               started through a tcp_wrappers-enabled xinetd. 
# 
#               The rules in this file can also be set up in 
#               /etc/hosts.allow with a 'deny' option instead. 
# 
#               See 'man 5 hosts_options' and 'man 5 hosts_access' 
#               for information on rule syntax. 
#               See 'man tcpd' for information on tcp_wrappers 
# 
sshd:ALL   ← 添加这一行，屏蔽来自所有的SSH连接请求
"/etc/hosts.deny" 14L, 469C written 
You have new mail in /var/spool/mail/root 
root@Cacti.Nagios:[/root]vi /etc/hosts.allow   ← 修改允许规则，在文尾添加相应行
# 
# hosts.allow   This file contains access rules which are used to 
#               allow or deny connections to network services that 
#               either use the tcp_wrappers library or that have been 
#               started through a tcp_wrappers-enabled xinetd. 
# 
#               See 'man 5 hosts_options' and 'man 5 hosts_access' 
#               for information on rule syntax. 
#               See 'man tcpd' for information on tcp_wrappers 
# 
sshd:192.168.7. 只允许192.168.7。网段的机器ssh登陆
~                                                                                        
~                                                                                        
~                                                                                        
"/etc/hosts.allow" 11L, 386C written                                   
 
root@Cacti.Nagios:[/root]su - admin 
admin@Cacti.Nagios:[/data]ssh-keygen -t rsa 
Generating public/private rsa key pair. 
Enter file in which to save the key (/data/.ssh/id_rsa):  
Created directory '/data/.ssh'. 
Enter passphrase (empty for no passphrase):  
Enter same passphrase again:  
Your identification has been saved in /data/.ssh/id_rsa. 
Your public key has been saved in /data/.ssh/id_rsa.pub. 
The key fingerprint is: 
e5:15:ba:be:59:ef:2e:74:df:b6:ee:e1:6a:24:be:da admin@Cacti.Nagios 
The key's randomart image is: 
+--[ RSA 2048]----+ 
|            .    | 
|           . .   | 
|          o .    | 
|         o o     | 
|        S o      | 
|         . ....  | 
|          o.+. o.| 
|          .=.o. =| 
|         .+Eo=B*.| 
+-----------------+ 
admin@Cacti.Nagios:[/data]ls -a 
.  ..  .bash_history  .bash_logout  .bash_profile  .bashrc  lost+found  .ssh  .viminfo 
admin@Cacti.Nagios:[/data]cd .ssh/ 
admin@Cacti.Nagios:[/data/.ssh]ll 
total 8 
-rw------- 1 admin admin 1751 Oct 12 17:19 id_rsa 
-rw-r--r-- 1 admin admin  401 Oct 12 17:19 id_rsa.pub 
admin@Cacti.Nagios:[/data/.ssh]cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys 
admin@Cacti.Nagios:[/data/.ssh]ls -a 
.  ..  authorized_keys  id_rsa  id_rsa.pub 
admin@Cacti.Nagios:[/data/.ssh]chmod 400 authorized_keys  
admin@Cacti.Nagios:[/data/.ssh]ll -a 
total 20 
drwx------ 2 admin admin 4096 Oct 12 17:20 . 
drwxr-xr-x 4 admin admin 4096 Oct 12 17:19 .. 
-r-------- 1 admin admin  401 Oct 12 17:20 authorized_keys 
-rw------- 1 admin admin 1751 Oct 12 17:19 id_rsa 
-rw-r--r-- 1 admin admin  401 Oct 12 17:19 id_rsa.pub 
 
至此，将私钥id_rsa导出到windows客户端上。然后删除生成的公钥id_rsa.pub。
重启sshd服务，使得刚才所做的配置修改生效。
root@Cacti.Nagios:[/root]/etc/rc.d/init.d/sshd restart  Stopping sshd:                                             [  OK  ]  Starting sshd:                                             [  OK  ] 

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