nomachine 是商业软件，只有客户端（client）是免费的！所以我们需要安装 freenx。
gksudo gedit /etc/apt/sources.list
添加源
deb ~brett/seveas/freenx dapper-seveas freenx
deb-src ~brett/seveas/freenx dapper-seveas freenx
获得并加入加密钥 key
wget ~brett/seveas/freenx/seveas.gpg -O- | sudo apt-key add -
sudo apt-get update
sudo aptitude install freenx
注意：我在 update 的时候报错，大约是 gpg key 有问题云云。但可以正常使用！你也可以尝试
wget 6.gpg -O- | sudo apt-key add -
NX 有几种安全模式：
以下为引用内容:
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NoMachine Keys: Allow login with the key shipped with the NoMachine ↑
│ client. This is not as secure, but it simplifies the configuration of ▮
│ clients. ▒
│ ▒
│ Custom keys: Create custom keys for freenx, while this is the most ▒
│ secure option you will have to distribute the server key to all involved ▒
│ clients, import your server's ▒
│ /var/lib/nxserver/home/.ssh/client.id_dsa.key to your nx client (custom ▒
│ keys are not supported upstream). ▒
│ ▒
│ Manual setup: setup freenx manually using /usr/sbin/nxsetup, leave ▒
│ existing configurations alone. ▒
│ ▒
│ Remove freenx keys: Remove or don't create keys and leave freenx
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一般选择最简单的 NoMachine client 模式即可。Custom keys 模式，需要把 /var/lib/nxserver/home 目录中的 .key 文件拷贝到客户端机器上。