> CentOS > CentOS入门 >

CentOS 7设置ssh服务自动启动

时间:2017-06-16 21:58  来源:linux.it.net.cn   作者:IT

实验环境：CentOS7 Minimal安装，安装过程及软件包见http://blog.csdn.net/capricorn90/article/details/52556174 
SSH的英文全称是Secure SHell。通过使用SSH，你可以把所有传输的数据进行加密，这样“中间人”这种攻击方式就不可能实现了，而且也能够防止DNS和IP欺骗。还有一个额外的好处就是传输的数据是经过压缩的，所以可以加快传输的速度。SSH有很多功能，它既可以代替telnet，又可以为ftp、pop、甚至ppp提供一个安全的“通道”。

SSH在Linux中的服务是sshd，安装openssh后才可开启。CentOS 7 安装后默认情况下是不启动sshd服务，即无法通过ssh服务远程连接。 
首先查看系统是否安装openssh，一般情况想都是默认安装了，

[root@localhost ~]# rpm -qa | grep ssh 
libssh2-1.4.3-10.el7.x86_64 
openssh-server-6.6.1p1-22.el7.x86_64 
openssh-clients-6.6.1p1-22.el7.x86_64 
openssh-6.6.1p1-22.el7.x86_64

如果没有安装可以通过yum在线安装。

[root@localhost ~]# yum install openssh

手动设置启动ssh服务

简单的设置就是在命令行中启动sshd服务。这样做比较快捷直接，但是只能对当前状态有效，一旦重启系统就丢失了该服务。

[root@localhost ~]# systemctl start sshd 
[root@localhost ~]# systemctl status sshd 
● sshd.service - OpenSSH server daemon 
Loaded: loaded (/usr/lib/systemd/system/sshd.service; enabled; vendor preset: enabled) 
Active: active (running) since Fri 2016-09-16 16:18:24 CST; 6h ago 
Docs: man:sshd(8) 
man:sshd_config(5) 
Main PID: 1031 (sshd) 
CGroup: /system.slice/sshd.service 
└─1031 /usr/sbin/sshd -D 
Sep 16 16:18:24 localhost.localdomain systemd[1]: Starting OpenSSH server daemon… 
Sep 16 16:18:25 localhost.localdomain sshd[1031]: Server listening on 0.0.0.0 port 22. 
Sep 16 16:18:25 localhost.localdomain sshd[1031]: Server listening on :: port 22. 
Sep 16 18:18:14 localhost.localdomain systemd[1]: Started OpenSSH server daemon. 
Sep 16 18:29:41 localhost.localdomain sshd[11847]: Accepted password for root from 192.168.92.1 port 55149 ssh2 
Sep 16 18:37:11 localhost sshd[12969]: Address 192.168.92.1 maps to localhost, but this does not map back to the address - POSSIBLE BREAK-IN ATTEMPT! 
Sep 16 18:37:12 localhost sshd[12969]: Accepted password for root from 192.168.92.1 port 55391 ssh2 
Sep 16 22:09:59 localhost sshd[15252]: Address 192.168.92.1 maps to localhost, but this does not map back to the address - POSSIBLE BREAK-IN ATTEMPT! 
Sep 16 22:10:02 localhost sshd[15252]: Accepted password for root from 192.168.92.1 port 64452 ssh2 
Sep 16 22:22:08 localhost systemd[1]: Started OpenSSH server daemon.

设置自动启动ssh服务

1、systemclt设置自动启动

通过systemctl命令可以将sshd服务加到开机自启动列表里。实现开机自动启动sshd服务。

[root@localhost ~]# systemctl enable sshd

2、修改ssh监听端口

在sshd_config文件中存放了端口、控制策略等信息。

[root@localhost ~]# vi /etc/ssh/sshd_config

#       $OpenBSD: sshd_config,v 1.93 2014/01/10 05:59:19 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:/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 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
#AddressFamily any
#ListenAddress 0.0.0.0
#ListenAddress ::

# The default requires 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
HostKey /etc/ssh/ssh_host_ecdsa_key
HostKey /etc/ssh/ssh_host_ed25519_key

# Lifetime and size of ephemeral version 1 server key
#KeyRegenerationInterval 1h
#ServerKeyBits 1024

# Ciphers and keying
#RekeyLimit default none

# 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

# 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
#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 yes

# 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
# 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'.
# WARNING: 'UsePAM no' is not supported in Red Hat Enterprise Linux and may cause several
# problems.
UsePAM yes

#AllowAgentForwarding yes
#AllowTcpForwarding yes
#GatewayPorts no
X11Forwarding yes
#X11DisplayOffset 10
#X11UseLocalhost yes
#PermitTTY yes
#PrintMotd yes
#PrintLastLog yes
#TCPKeepAlive yes
#UseLogin no
UsePrivilegeSeparation sandbox          # Default for new installations.
#PermitUserEnvironment no
#Compression delayed
#ClientAliveInterval 0
#ClientAliveCountMax 3
#ShowPatchLevel no
#UseDNS yes
#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
  • 1
  • 2
  • 3
  • 4
  • 5
  • 6
  • 7
  • 8
  • 9
  • 10
  • 11
  • 12
  • 13
  • 14
  • 15
  • 16
  • 17
  • 18
  • 19
  • 20
  • 21
  • 22
  • 23
  • 24
  • 25
  • 26
  • 27
  • 28
  • 29
  • 30
  • 31
  • 32
  • 33
  • 34
  • 35
  • 36
  • 37
  • 38
  • 39
  • 40
  • 41
  • 42
  • 43
  • 44
  • 45
  • 46
  • 47
  • 48
  • 49
  • 50
  • 51
  • 52
  • 53
  • 54
  • 55
  • 56
  • 57
  • 58
  • 59
  • 60
  • 61
  • 62
  • 63
  • 64
  • 65
  • 66
  • 67
  • 68
  • 69
  • 70
  • 71
  • 72
  • 73
  • 74
  • 75
  • 76
  • 77
  • 78
  • 79
  • 80
  • 81
  • 82
  • 83
  • 84
  • 85
  • 86
  • 87
  • 88
  • 89
  • 90
  • 91
  • 92
  • 93
  • 94
  • 95
  • 96
  • 97
  • 98
  • 99
  • 100
  • 101
  • 102
  • 103
  • 104
  • 105
  • 106
  • 107
  • 108
  • 109
  • 110
  • 111
  • 112
  • 113
  • 114
  • 115
  • 116
  • 117
  • 118
  • 119
  • 120
  • 121
  • 122
  • 123
  • 124
  • 125
  • 126
  • 127
  • 128
  • 129
  • 130
  • 131
  • 132
  • 133
  • 134
  • 135
  • 136
  • 137
  • 138
  • 139
  • 140
  • 141
  • 142
  • 143
  • 144
  • 145
  • 146
  • 147
  • 148
  • 149
  • 150
  • 151
  • 152
  • 153
  • 1
  • 2
  • 3
  • 4
  • 5
  • 6
  • 7
  • 8
  • 9
  • 10
  • 11
  • 12
  • 13
  • 14
  • 15
  • 16
  • 17
  • 18
  • 19
  • 20
  • 21
  • 22
  • 23
  • 24
  • 25
  • 26
  • 27
  • 28
  • 29
  • 30
  • 31
  • 32
  • 33
  • 34
  • 35
  • 36
  • 37
  • 38
  • 39
  • 40
  • 41
  • 42
  • 43
  • 44
  • 45
  • 46
  • 47
  • 48
  • 49
  • 50
  • 51
  • 52
  • 53
  • 54
  • 55
  • 56
  • 57
  • 58
  • 59
  • 60
  • 61
  • 62
  • 63
  • 64
  • 65
  • 66
  • 67
  • 68
  • 69
  • 70
  • 71
  • 72
  • 73
  • 74
  • 75
  • 76
  • 77
  • 78
  • 79
  • 80
  • 81
  • 82
  • 83
  • 84
  • 85
  • 86
  • 87
  • 88
  • 89
  • 90
  • 91
  • 92
  • 93
  • 94
  • 95
  • 96
  • 97
  • 98
  • 99
  • 100
  • 101
  • 102
  • 103
  • 104
  • 105
  • 106
  • 107
  • 108
  • 109
  • 110
  • 111
  • 112
  • 113
  • 114
  • 115
  • 116
  • 117
  • 118
  • 119
  • 120
  • 121
  • 122
  • 123
  • 124
  • 125
  • 126
  • 127
  • 128
  • 129
  • 130
  • 131
  • 132
  • 133
  • 134
  • 135
  • 136
  • 137
  • 138
  • 139
  • 140
  • 141
  • 142
  • 143
  • 144
  • 145
  • 146
  • 147
  • 148
  • 149
  • 150
  • 151
  • 152
  • 153

首先修改端口，端口设置为自定义端口，即1024之后的端口，这里设置为8090。

port 8090
  • 1
  • 1

禁止空密码用户登录。

PermitEmptyPasswords no
  • 1
  • 1

开启密码登录授权（默认即开启）

PasswordAuthentication yes
  • 1
  • 1

禁止root账户使用ssh登录，这种设置通常用于互联网服务器，防止提权后用root账户登录搞破坏。

PermitRootLogin no
  • 1
  • 1

注意其中关于port的提示文字

# 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
  • 1
  • 2
  • 3
  • 1
  • 2
  • 3

修改端口的时候需要添加到防火墙的控制中，否则无法使用ssh连接。

[root@localhost ~]# semanage port -l | grep ssh #查看当前ssh服务监听的端口  ssh_port_t tcp 22  [root@localhost ~]# semanage port -a -t ssh_port_t -p tcp 8090 #增加监听端口8090

[root@localhost ~]# semanage port -l | grep ssh  ssh_port_t tcp 8090,22

semanage只是端口工具，修改防火墙只能使用firewall-cmd

[root@localhost ssh]# yum provides firewall-cmd #查找防火墙工具所在的包  Loaded plugins: fastestmirror  Loading mirror speeds from cached hostfile  * base: mirror.bit.edu.cn  * extras: mirrors.btte.NET  * updates: mirrors.btte.net  firewalld-0.3.9-14.el7.noarch : A firewall daemon with D-BUS interface providing a dynamic firewall  Repo : base  Matched from:  Filename : /usr/bin/firewall-cmd

[root@localhost ssh]# yum -y install firewalld #安装防火墙工具

[root@localhost ssh]# systemctl start firewalld #启动防火墙服务

[root@localhost ssh]# systemctl status firewalld #查看防火墙状态  ● firewalld.service - firewalld - dynamic firewall daemon  Loaded: loaded (/usr/lib/systemd/system/firewalld.service; enabled; vendor preset: enabled)  Active: active (running) since Sat 2016-09-17 04:22:15 CST; 15s ago  Main PID: 16979 (firewalld)  CGroup: /system.slice/firewalld.service  └─16979 /usr/bin/Python -Es /usr/sbin/firewalld –nofork –nopid  Sep 17 04:22:14 localhost systemd[1]: Starting firewalld - dynamic firewall daemon…  Sep 17 04:22:15 localhost systemd[1]: Started firewalld - dynamic firewall daemon.  [root@localhost ssh]# firewall-cmd –zone=public –add-port=8090/tcp –permanent #防火墙中允许8090端口通过  success

[root@localhost ssh]# semanage port -m -t ssh_port_t -p tcp 8090 #将ssh服务修改为8090端口  [root@localhost ssh]# firewall-cmd –zone=public –remove-port=22/tcp –permanent #删除22端口  success  [root@localhost ssh]# firewall-cmd –reload #重新加载防火墙服务配置  success




(责任编辑：IT)
    最近关注
    热点内容