安装json gem'mkmf.rb时出错无法找到ruby的头文件'

对于上下文,它在具有防火墙的远程服务器上.我正在通过代理设置我的环境.我有ruby 1.8.7.当我尝试宝石安装..

sudo gem install --http-proxy : json

我收到以下错误:

Building native extensions.  This could take a while...
ERROR:  Error installing json:
        ERROR: Failed to build gem native extension.

/usr/bin/ruby extconf.rb
mkmf.rb can't find header files for ruby at /usr/lib/ruby/ruby.h

Gem files will remain installed in /usr/lib64/ruby/gems/1.8/gems/json-1.8.1 for inspection.
Results logged to /usr/lib64/ruby/gems/1.8/gems/json-1.8.1/ext/json/ext/generator/gem_make.out

由于我不确定问题是什么,我用Google搜索并找到了这些

gem install:无法构建gem原生扩展(找不到头文件) - 这里的说明似乎特定于正在安装的gem.

如何安装json gem - 无法构建gem native扩展 这似乎是略有不同的错误.

任何提示？谢谢!