修改/etc/hosts文件

sudo gedit /etc/hosts127.0.0.1 localhost 192.168.222.129 master 下面分別對應(yīng)三個機器的IP地址，用ifconfig查看 192.168.222.130 slave1 192.168.222.131 slave2# The following lines are desirable for IPv6 capable hosts ::1 ip6-localhost ip6-loopback fe00::0 ip6-localnet ff00::0 ip6-mcastprefix ff02::1 ip6-allnodes ff02::2 ip6-allrouters測試是否能ping通ping master/slave1/slave2

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分別給3臺機器都創(chuàng)建hadoop用戶，方便進行管理

二、 建立hadoop運行帳號 即為hadoop集群專門設(shè)置一個用戶組及用戶 (1)創(chuàng)建hadoop用戶組 (2)創(chuàng)建hadoop用戶sudo adduser -ingroup hadoop hadoop回車后會提示輸入新的UNIX密碼，這是新建用戶hadoop的密碼，輸入回車即可。 最后確認信息是否正確，如果沒問題，輸入 Y，回車即可。 (3)為hadoop用戶添加權(quán)限(給hadoop用戶賦予和root用戶同樣的權(quán)限) 輸入：sudo gedit /etc/sudoers~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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用新增加的hadoop用戶登錄Ubuntu系統(tǒng),進行SSH的配置

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配置ssh免密碼登錄hadoop工作時，各節(jié)點要相互通訊，正常情況下linux之間通訊要提供用戶名、密碼（目的是保證通訊安全），如果 需要人工干預(yù)輸入密碼，顯然不方便，做這一步的目的，是讓各節(jié)點能自動通過安全認證，不影響正常通訊。安裝ssh: sudo apt-get install openssh-server 安裝完成后，啟動服務(wù):sudo /etc/init.d/ssh start 查看服務(wù)是否正確啟動：ps -e | grep ssh

一.使用SSH使每一臺機器免密碼登錄自己本機

//下面以mster機器為例：1.使登錄身份始終是hadoop，操作目錄始終是/home/master master@master:~$ su hadoop #切換成hadoop(以hadoop身份登錄到系統(tǒng)) hadoop@master:~$cd /home/hadoop(進入個人主目錄，默認為/home/hadoop)2.生成公鑰私鑰id_rsa id_rsa.pub hadoop@master:~$ ssh-keygen -t rsa -P '' (注：最后是二個單引號，生成公鑰私鑰) Generating public/private rsa key pair. Enter file in which to save the key (/home/hadoop/.ssh/id_rsa): Created directory '/home/hadoop/.ssh'. Your identification has been saved in /home/hadoop/.ssh/id_rsa. Your public key has been saved in /home/hadoop/.ssh/id_rsa.pub. The key fingerprint is: cd:67:f5:0f:15:a1:42:ad:7a:29:78:3b:ca:8c:3a:b7 hadoop@slave1 The key's randomart image is: +--[ RSA 2048]----+ | .. o.| | . .. .| | .... .| | o ... o | | S + + . .| | . + = ..| | . + .| | . .+ o | | .+E.+. . | +-----------------+解釋：以rsa算法，生成公鑰、私鑰對，-P ''表示空密碼。該命令 運行完后，會在個人主目錄/home/hadoop下生成.ssh目錄，里面會 有二個文件id_rsa（私鑰） ,id_rsa.pub(公鑰)，即： hadoop@master:~$ ls .ssh #查看是否生成公鑰私鑰 id_rsa id_rsa.pub3.導(dǎo)入公鑰hadoop@master:cat .ssh/id_rsa.pub >> .ssh/authorized_keys 解釋：會在個人主目錄/home/hadoop/.ssh目錄下生成authorized_keys，即 hadoop@master:~$ ls .ssh #查看是否生成authorized_keys authorized_keys id_rsa id_rsa.pub4.修改文件權(quán)限 hadoop@master:chmod 600 .ssh/authorized_keys5.進行SSH測試是否能免密碼連接本機執(zhí)行完以后，可以在本機上測試下，用ssh連接自己，即：ssh localhost (或ssh master)【注解】廢話不多說，直接上下面中3個中括號中的命令 【hadoop@master:~$ ssh localhost】 #連接自己 The authenticity of host 'localhost (127.0.0.1)' can't be established. ECDSA key fingerprint is d5:f7:47:44:7b:9f:55:ac:e7:ed:6c:8d:f6:98:68:72. Are you sure you want to continue connecting (yes/no)? yes #輸入yes Warning: Permanently added 'localhost' (ECDSA) to the list of known hosts. Welcome to Ubuntu 14.04.5 LTS (GNU/Linux 4.4.0-31-generic x86_64)* Documentation: https://help.ubuntu.com/New release '16.04.3 LTS' available. Run 'do-release-upgrade' to upgrade to it.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.【hadoop@master:~$ exit】 #連接成功后，退出exit 注銷 Connection to localhost closed.【hadoop@master:~$ ssh localhost】 #重新鏈接，不需要密碼，此時成功配置了master機器的SSH Welcome to Ubuntu 14.04.5 LTS (GNU/Linux 4.4.0-31-generic x86_64)* Documentation: https://help.ubuntu.com/281 packages can be updated. 193 updates are security updates.New release '16.04.3 LTS' available. Run 'do-release-upgrade' to upgrade to it.Last login: Fri Aug 11 10:22:27 2017 from localhosthadoop@master:~$ 【終于】到此位置，成功搞定一臺機器：master，下面我們再進行slave1，slave2機器的SSH免密碼登錄的配置。（配置方法同上）

二. 將slave公鑰文件復(fù)制到master（只操作slave機器，不操作master）

a)用scp命令，把公鑰文件發(fā)放給master（即：剛才已經(jīng)搞定的那臺機器） #在slave1上： scp .ssh/id_rsa.pub hadoop@master:/home/hadoop/id_rsa_01.pub#在slave2上： scp .ssh/id_rsa.pub hadoop@master:/home/hadoop/id_rsa_02.pubb)這二行執(zhí)行完后，回到master中，查看下/home/hadoop目錄，應(yīng)該有二個新文 件id_rsa_01.pub、id_rsa_02.pub，然后在master上，導(dǎo)入這二個公鑰cat id_rsa_01.pub >> .ssh/authorized_keys cat id_rsa_02.pub >> .ssh/authorized_keys這樣，master這臺機器就有所有3臺機器的公鑰了。

三. 將master上的“最全”公鑰，復(fù)制到其它機器slave1.slave2

a) 繼續(xù)保持在master上，scp .ssh/authorized_keys hadoop@slave1:/home/hadoop/.ssh/authorized_keysscp .ssh/authorized_keys hadoop@slave2:/home/hadoop/.ssh/authorized_keysb) 修改其它機器上authorized_keys文件的權(quán)限slave1以及slave2機器上，均執(zhí)行命令chmod 600 .ssh/authorized_keys

四. 驗證能否通過SSH無密碼連接其他機器

在每個虛擬機上，均用 ssh 其它機器的hostname 驗證下，如果能正常無密碼連接成功，表示ok以master機器，連接slave1，slave2機器為例： （1）切換到hadoop用戶 master@master:~$ su hadoop （2）測試無密碼連接slave1 hadoop@master:/home/master$ ssh slave1 Welcome to Ubuntu 14.04.5 LTS (GNU/Linux 4.4.0-31-generic x86_64)* Documentation: https://help.ubuntu.com/281 packages can be updated. 193 updates are security updates.New release '16.04.3 LTS' available. Run 'do-release-upgrade' to upgrade to it.Last login: Fri Aug 11 11:02:00 2017 from slave2 （3）測試無密碼連接slave2 hadoop@slave1:~$ ssh slave2 Welcome to Ubuntu 14.04.5 LTS (GNU/Linux 4.4.0-31-generic x86_64)* Documentation: https://help.ubuntu.com/281 packages can be updated. 193 updates are security updates.New release '16.04.3 LTS' available. Run 'do-release-upgrade' to upgrade to it.Last login: Fri Aug 11 11:02:11 2017 from slave2【發(fā)現(xiàn)】master可以無密碼連接slave1，slave2，同理，下面 分別進行測試slave1，slave2~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~【重點】非常容易犯的錯誤配置SSH成功后，每次都要"先切換到hadoop用戶"下，才可以SSH成功（1）切換到用戶hadoop master@master:~$ su hadoop 密碼： （2）SSH本機器 hadoop@master:/home/master$ ssh master Welcome to Ubuntu 14.04.5 LTS (GNU/Linux 4.4.0-31-generic x86_64)* Documentation: https://help.ubuntu.com/New release '16.04.3 LTS' available. Run 'do-release-upgrade' to upgrade to it.Last login: Fri Aug 11 18:12:54 2017 from master hadoop@master:~$ （3）SSH slave1機器 hadoop@master:~$ ssh slave1 Welcome to Ubuntu 14.04.5 LTS (GNU/Linux 4.4.0-31-generic x86_64)* Documentation: https://help.ubuntu.com/New release '16.04.3 LTS' available. Run 'do-release-upgrade' to upgrade to it.Last login: Fri Aug 11 18:16:14 2017 from master hadoop@slave1:~$ （3）SSH slave2機器 hadoop@slave1:~$ ssh slave2 Welcome to Ubuntu 14.04.5 LTS (GNU/Linux 4.4.0-31-generic x86_64)* Documentation: https://help.ubuntu.com/New release '16.04.3 LTS' available. Run 'do-release-upgrade' to upgrade to it.Last login: Fri Aug 11 17:35:47 2017 from slave1 hadoop@slave2:~$

[小結(jié)]

小結(jié)：該步驟非常重要，主要思路是在各節(jié)點上生成公鑰、私鑰，然后將公鑰發(fā)放其它所有節(jié)點。RSA算法是非 對稱加密算法，僅公布“公鑰”，只要私鑰不外泄，還是不能解密的，所以安全性依然有保障。如果本步驟失敗，根據(jù)我個人經(jīng)驗，多半是權(quán)限問題，請檢查hadoop是否具有足夠權(quán)限，建議將hadoop加 入sudoers列表及root用戶組。另外,這里也整理了一些SSH免密碼設(shè)置失敗的原因,請移步 ssh 免密碼設(shè)置失敗原因總結(jié)

Hadoop集群安裝配置教程_Hadoop2.6.0_Ubuntu/CentOShttp://dblab.xmu.edu.cn/blog/285/

總結(jié)

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