ubuntu18.04 openssh客户端和服务端 安装及配置

openssl客户端和服务器

• SSH分客户端openssh-client和openssh-server
• 如果你只是想登陆别的机器的SSH只需要安装openssh-client（ubuntu有默认安装，如果没有则sudoapt-get install openssh-client），如果要使本机开放SSH服务就需要安装openssh-server。

1 openSSH客户端的安装与配置

Ubuntu缺省已经安装了ssh client。

sudo apt-get install ssh 或者 sudo apt-get installopenssh-client
ssh-keygen  //(按回车设置默认值)

按缺省生成id_rsa和id_rsa.pub文件，分别是私钥和公钥，存储于/home/xywu/.ssh/id_rsa。

说明：如果sudo apt-get insall ssh出错，无法安装可使用sudo apt-get install openssh-client进行安装。
假定服务器ip为192.168.1.1，ssh服务的端口号为22，服务器上有个用户为root；
用ssh登录服务器的命令为：

2 openssl服务端

Ubuntu缺省没有安装SSH Server，使用以下命令安装：

sudo apt-get install openssh-server

然后确认sshserver是否启动了：（或用“netstat -tlp”命令）

sudo ps -e|grep ssh

如果只有ssh-agent那ssh-server还没有启动，需要sudo service ssh start，如果看到sshd那说明ssh-server已经启动了。

如果没有则可以这样启动：

sudo service ssh start

事实上如果没什么特别需求，到这里 OpenSSH Server 就算安装好了。但是进一步设置一下，可以让 OpenSSH 登录时间更短，并且更加安全。这一切都是通过修改 openssh 的配置文件 sshd_config 实现的。

3 SSH配置

ssh-server配置文件位于/etc/ssh/sshd_config，在这里可以定义SSH的服务端口，默认端口是22，你可以自己定义成其他端口号，如222。然后重启SSH服务：

sudo service ssh restart

通过修改配置文件/etc/ssh/sshd_config，可以改ssh登录端口和禁止root登录。改端口可以防止被端口扫描。

sudo cp/etc/ssh/sshd_config /etc/ssh/sshd_config.original
sudo chmod a-w /etc/ssh/sshd_config.original
gedit  /etc/ssh/sshd_config

将sshd_config 改成一下形式：

#	$OpenBSD: sshd_config,v 1.101 2017/03/14 07:19:07 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/bin:/bin:/usr/sbin:/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.

Port 22
#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

# Logging
#SyslogFacility AUTH
#LogLevel INFO

# Authentication:

#LoginGraceTime 2m
PermitRootLogin yes
#StrictModes yes
#MaxAuthTries 6
#MaxSessions 10

#PubkeyAuthentication yes

# Expect .ssh/authorized_keys2 to be disregarded by default in future.
#AuthorizedKeysFile	.ssh/authorized_keys .ssh/authorized_keys2

#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!
PasswordAuthentication no
#PermitEmptyPasswords no

# Change to yes to enable challenge-response passwords (beware issues with
# some PAM modules and threads)
ChallengeResponseAuthentication no

# Kerberos options
#KerberosAuthentication no
#KerberosOrLocalPasswd yes
#KerberosTicketCleanup yes
#KerberosGetAFSToken no

# GSSAPI options
#GSSAPIAuthentication no
#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 yes

#AllowAgentForwarding yes
#AllowTcpForwarding yes
#GatewayPorts no
X11Forwarding yes
#X11DisplayOffset 10
#X11UseLocalhost yes
#PermitTTY yes
PrintMotd no
#PrintLastLog yes
#TCPKeepAlive yes
#UseLogin no
#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

# Allow client to pass locale environment variables
AcceptEnv LANG LC_*

# override default of no subsystems
Subsystem	sftp	/usr/lib/openssh/sftp-server

# Example of overriding settings on a per-user basis
#Match User anoncvs
#	X11Forwarding no
#	AllowTcpForwarding no
#	PermitTTY no
#	ForceCommand cvs server

配置完成后重启：

sudo service ssh restart

sshd_config配置教程

4 使用putty远程登录

安装putty

sudo apt-get install putty
sudo putty

添加ssh私钥