网上有很多介绍在Ubuntu下开启SSH服务的文章，但大多数介绍的方法测试后都不太理想，均不能实现远程登录到Ubuntu上，最后分析原因是都没有真正开启ssh-server服务。最终成功的方法如下：

sudo apt-get install openssh-server

Ubuntu缺省安装了openssh-client,所以在这里就不安装了，如果你的系统没有安装的话，再用apt-get安装上即可。

然后确认sshserver是否启动了：

ps -e |grep ssh

如果只有ssh-agent那ssh-server还没有启动，需要/etc/init.d/ssh start，如果看到sshd那说明ssh-server已经启动了。

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 /etc/init.d/ssh restart

ssh连接：ssh linuxidc@192.168.1.1

摘自：http://www.linuxidc.com/Linux/2010-02/24349.htm

久！

2011-08-23 12:57 上传

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后来找到了http://www.unixtutorial.org/2009 ... re-shell-in-ubuntu/，马上如有天助，跟我遇到的问题都一样！原来是要输入yes阿！我习惯性的输入的都是y，哎！看样子也的看清楚答问题阿！

SSH (Secure SHell) is possibly the best way to remotely access a Unix system – it's very secure thanks to automatic encryption of all the traffic, and it's also quite universal because you can do all sorts of things: access remote command line shell, forward graphics session output, establish network tunnels and set up port redirections. Today I'm going to show you how to get started with SSH in Ubuntu.

Installing SSH server in Ubuntu

By default, your system will have no SSH service enabled, which means you won't be able to connect to it remotely using SSH protocol (TCP port 22). This means that installing SSH server will be one of the first post-install steps on your system.

The most common SSH implementation is OpenSSH server, and that's exactly what you want to install.

Log in with your standard username and password, and run the following command to install openssh-server. You should be using the same username that you specified when installing Ubuntu, as it will be the only account with sudo privileges to run commands as root:

ubuntu$ sudo apt-get install openssh-server

[sudo] password for greys:

Reading package lists... Done

Building dependency tree

Reading state information... Done

Suggested packages:

rssh molly-guard openssh-blacklist openssh-blacklist-extra

The following NEW packages will be installed:

openssh-server

0 upgraded, 1 newly installed, 0 to remove and 75 not upgraded.

Need to get 285kB of archives.

After this operation, 782kB of additional disk space will be used.

Get:1 http://ie.archive.ubuntu.com jaunty/main openssh-server 1:5.1p1-5ubuntu1 [

285kB]

Fetched 285kB in 0s (345kB/s)

Preconfiguring packages ...

Selecting previously deselected package openssh-server.

(Reading database ... 101998 files and directories currently installed.)

Unpacking openssh-server (from .../openssh-server_1%3a5.1p1-5ubuntu1_i386.deb) .

..

Processing triggers for ufw ...

Processing triggers for man-db ...

Setting up openssh-server (1:5.1p1-5ubuntu1) ...

Creating SSH2 RSA key; this may take some time ...

Creating SSH2 DSA key; this may take some time ...

* Restarting OpenBSD Secure Shell server sshd                           [ OK ]

Verifying your SSH server works

While you're still on your local desktop session, you can use the ps command to confirm that SSH daemon (sshd) is running:

ubuntu$ ps -aef | grep sshd

root     24114     1  0 15:18 ?        00:00:00 /usr/sbin/sshd

Now that you see it's there, it's time to try connecting:

ubuntu$ ssh localhost

Since this is the first time you're trying to connect using SSH, you'll have to answer yes to the following question:

The authenticity of host 'localhost (::1)' can't be established.

RSA key fingerprint is 18:4d:96:b3:0d:25:00:c8:a1:a3:84:5c:9f:1c:0d:a5.

Are you sure you want to continue connecting (yes/no)? yes

… you'll then be prompted for your own password (remember, the system treats such connection request as if you were connecting remotely, so it can't trust you without confirming your password):

Warning: Permanently added 'localhost' (RSA) to the list of known hosts.

greys@localhost's password:

.. and finally you'll see the usual Ubuntu (Jaunty in this example) banner and prompt:

Linux ubuntu 2.6.28-11-generic #42-Ubuntu SMP Fri Apr 17 01:57:59 UTC 2009 i686

The programs included with the Ubuntu system are free software;

the exact distribution terms for each program are described in the

individual files in /usr/share/doc/*/copyright.

Ubuntu comes with ABSOLUTELY NO WARRANTY, to the extent permitted by

applicable law.

To access official Ubuntu documentation, please visit:

http://help.ubuntu.com/

Last login: Fri May 15 15:18:34 2009 from ubuntu

ubuntu$

That's it, providing you have your networking configured and you know your IP address or hostname, you can start connecting to your Ubuntu box from remote systems, using the same command.  Enjoy!

然后本机是可以连接了！但是外部用putty还是不行！sudo ufw disable 关闭ufw防火墙，发现貌似根本没开！（也上网查了，自己不装，系统不会安装的！）
后来在http://forum.ubuntu.org.cn/viewtopic.php?t=40438，找到了这一行，貌似是系统的安全规则

iptables是内核模块删除不了滴

现查看一下你iptables的规则

sudo iptables -L

sudo iptables -t nat -L

如果都是空的就不是iptables的问题

如果有许多规则的话就清空规则并修改默认策略

sudo iptables -F

sudo iptables -t nat -F

sudo iptables -P ACCEPT

sudo iptables -t nat -P ACCEPT

按着弄了一遍！最后两条都出现问题了！忘记截图了！好像是说没有这个命令，请查阅help什么的！不管！弄完，我去别的电脑上用putty连接，出现证书验证，yes，进入了！输入用户名后，有点慢，修改sudo gedit /etc/ssh/sshd_config

找到 GSSAPI options 这一节，将下面两行注释掉：

#GSSAPIAuthentication yes

#GSSAPIDelegateCredentials no

然后重新启动 ssh 服务即可：

sudo /etc/init.d/ssh restart

摘自：http://blog.istef.info/2008/10/02/setup-ssh-server-on-ubuntu-server/

2011-08-23 12:58 上传

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我的本来就是注释掉了阿！呵呵！不修改了！
以上是我安装ssh，解决的全过程！留着备用！

http://bbs.chinaunix.net/thread-3585704-1-1.html