还有 4 天时间。

Author:yangyingchao, 2011-04-01

RT 。
很期待。

漫长的等待之后， Gnome 3 终于如期发布了。 折腾了两天，又购入了一块独立显卡，终于把 gnome 3 成功的安装上了。

Gentoo: Emerge errors after a Python upgrade?

If you encounter seemingly “strange” Python errors when emerging apps after a Python upgrade, execute:

# python-updater -v

This will rebuild packages that are broken due to the Python upgrade (Note: You can also manually emerge the packages python-updater lists)

简介：
转载的文章，如何选择开源许可证。
转载请注明出处。

如何选择开源许可证？

作者： 阮一峰

日期： 2011年5月 2日

如何为代码选择开源许可证，这是一个问题。

世界上的开源许可证，大概有上百种。很少有人搞得清楚它们的区别。即使在最流行的六种----GPL、BSD、MIT、Mozilla、Apache和LGPL----之中做选择，也很复杂。

乌克兰程序员Paul Bagwell，画了一张分析图，说明应该怎么选择。这是我见过的最简单的讲解，只用两分钟，你就能搞清楚这六种许可证之间的最大区别。

下面是我制作的中文版，请点击看大图。

（完）

文档信息

• 版权声明：自由转载-非商用-非衍生-保持署名 | Creative Commons BY-NC-ND 3.0
• 原文网址：http://www.ruanyifeng.com/blog/2011/05/how_to_choose_free_software_licenses.html
• 最后修改时间：2011年5月 2日 01:27

Author:yangyingchao, 2011-05-03

LANG="zh_CN.UTF-8"
LC_CTYPE="zh_CN.UTF-8"

XMODIFIERS="@im=fcitx"

XIM=fcitx
XIM_PROGRAM=fcitx
XIM_ARGS="-d"

GTK_IM_MODULE=fcitx
QT_IM_MODULE=fcitx

简介：
转载，介绍了通过私钥/公钥对来实现 ssh 无密码登录的方法。 其中，值得注意的是， client 端和 server 端的几个文件和文件夹的权限的设置。
转载请注明出处。

4. SSH with Keys in a console window

This first short wil learn us how to generate a key without a passphrase, and use it in a console.

4.1 Creating A Key

When you want to use ssh with keys, the first thing that you will need is a key. If you want to know more about how this mechanism works you can have a look in chapter 3, SSH essentials. Hence there are 2 versions, we will show examples for the both of them.

4.2 Protocol version 1 key generation

To create the most simple key, with the default encryption, open up a console, and enter the following command :

---

[dave@caprice dave]$ ssh-keygen 

---

Wil output the following :

---

Generating public/private rsa1 key pair. Enter file in which to save the key (/home/dave/.ssh/identity): /home/dave/.ssh/identity Enter passphrase (empty for no passphrase): Enter same passphrase again: Your identification has been saved in /home/dave/.ssh/identity. Your public key has been saved in /home/dave/.ssh/identity.pub. The key fingerprint is: 22:bc:0b:fe:f5:06:1d:c0:05:ea:59:09:e3:07:8a:8c dave@caprice 

---

When asked for a "passphrase", we won't enter one. Just press enter twice.

The ssh-keygen program will now generate both your public and your private key. For the sake of this first simple tutorial I will call these files by their default names "identity" and the public key "identity.pub".

Your keys are stored in the .ssh/ directory in your home directory, but you can store them where ever you'd like. Good practice is to backup your keys on a floppy. If you do so, guard this floppy with your life!

* Note: specifying a key type may be mandatory on your system. In that case, skip to the version 2 key geneation process.

Lets have a look at your keys.

---

cd ~.ssh; ls -l -rw-------    1 dave     dave          526 Nov  2 01:33 identity -rw-r--r--    1 dave     dave          330 Nov  2 01:33 identity.pub 

---

The file identity contains your private key. YOU SHOULD GUARD THIS KEY WITH YOUR LIFE! This key is used to gain access on systems which have your private key listed in their authorized keys file. I cannot stress this enough, dont have your keys drifting around. Also, make sure your private key always is chmod 600, so other users on the system won't have access to it.

The file identity.pub contains your public key, which can be added to other system's authorized keys files. We will get to adding keys later.

4.3 Protocol version 2 key generation

Creating a version 2 keypair is much like creating a version 1 keypair. Except for the fact that the SSH protocol version 2 uses different encryption algorithms for its encryption. In this case we can even choos it ourselves! Huray! To find out which versions are available on your system I'd advise you to have a look in the ssh-keygen manpage.

In our example we wil create a keypair using dsa encryption. This can be done by passing the key encryption method type to ssh-keygen. This is done in the following way :

---

[dave@caprice dave]$ ssh-keygen -t dsa 

---

Which will output the following :

---

[dave@caprice dave]$ ssh-keygen -t dsa Generating public/private dsa key pair. Enter file in which to save the key (/home/dave/.ssh/id_dsa): Enter passphrase (empty for no passphrase): Enter same passphrase again: Your identification has been saved in /home/dave/.ssh/id_dsa. Your public key has been saved in /home/dave/.ssh/id_dsa.pub. The key fingerprint is: 7b:ab:75:32:9e:b6:6c:4b:29:dc:2a:2b:8c:2f:4e:37 dave@caprice 

---

Again, we will retain the default locations, and we will not use a passphrase either.

Your keys are stored in the .ssh/ directory in your home directory.

Lets have a look at your keys.

---

cd ~.ssh; ls -l -rw-------    1 dave     dave          526 Nov  3 01:21 id_dsa -rw-r--r--    1 dave     dave          330 Nov  3 01:21 id_dsa.pub 

---

The file id_dsa contains your version 2 private key.

The file id_dsa.pub contains your version 2 public key, which can be added to other system's authorized keys file.

Again, I have listed a full ls -l with permissions, make sure you have the permissions set up correctly, otherwise other users may be able to snatch it from you. It is also a good idea to give your keys a non-standard name, since it makes guessing the name of your keypair files more easy.

4.4 Placing the public key on the remote server

To be able to log in to remote systems using your pair of keys, you will first have to add your public key on the remote server to the authorized_keys (for version 1) file, and the authorized_keys2 (for version2) file in the .ssh/ directory in your home directory on the remote machine.

In our example we will assume you don't have any keys in the authorized_keys files on the remote server. (Hint: If you do not have a remote shell, you can always use your own useraccount on your local machine as a remote shell (ssh localhost))

First we will upload the public keys to the remote server :

---

[dave@capricedave]$ cd .ssh/ [dave@caprice .ssh]$ scp identity.pub dave@192.168.1.3:./identity.pub identity.pub    100% |*****************************************************|   526       00:00 [dave@caprice .ssh]$ scp id_dsa.pub dave@192.168.1.3:./id_dsa.pub identity.pub    100% |*****************************************************|   614       00:00 

---

This will place your keys in your home directory on the remote server. After that we will login on the remote server using ssh or telnet the conventional way... with a password.

When you are logged in you should create a .ssh directory, and inside the .ssh/ directory create an authorized_keys and an authorized_keys2 file and add the keys to the files. Make sure the files are not readable for other users/groups. chmod 600 authorized_keys* does the trick.

Adding the public key for version 1 works like this:

---

[dave@caprice dave]$ ssh 192.168.1.3 -v   [I edited out the verbose output, and entered the password]   [Remember kids, always use -v so dont try this at home :) ]  [dave@julia dave]$ mkdir .ssh [dave@julia dave]$ chmod 700 .ssh [dave@julia dave]$ cd .ssh [dave@julia .ssh]$ touch authorized_keys [dave@julia .ssh]$ chmod 600 authorized_keys [dave@julia .ssh]$ cat ../identity.pub >> authorized_keys [dave@julia .ssh]$ rm ../identity.pub 

---

Placing the key for version 2 works about the same :

---

[dave@julia dave]$ cd .ssh [dave@julia .ssh]$ touch authorized_keys2 [dave@julia .ssh]$ chmod 600 authorized_keys2 [dave@julia .ssh]$ cat ../id_dsa.pub >> authorized_keys2 [dave@julia .ssh]$ rm ../id_dsa.pub 

---

If you take a little peek inside your public key files, you will find it to be a bunch of crypto, separated over a couple of rules. The public key is *1 line*. It is worth to note that the entire public key file should be one line in the authorized_keys files. So using >> is preferred over copying and pasting it from one document to another. This could put line breaks in your key which makes it useless.

Either way, your keys are in place, you are ready to go to the final step and log in using your keys.

4.5 Log in using your key

To log in using your key use the ssh command. We will add -1 to make sure we are using SSH Protocol version 1.

---

ssh -1 -v dave@192.168.1.3 

---

This logs you into a system using your version 1 key.

Try it again, now for version 2

---

ssh -2 -v dave@192.168.1.3 

---

Have a look in the output of both ssh logins and you will be able to see some differences between version 1 and 2.

---

Author:yangyingchao, 2011-05-03

人生只有900个月