由于yum install aria2无法找到安装包，试了好几个源，都找不到，于是自己找了一些地址：
1、下载安装包：
# wget http://ftp.tu-chemnitz.de/pub/linux/dag/redhat/el6/en/x86_64/rpmforge/rpms/aria2-1.16.4-1.el6.rf.x86_64.rpm
# wget http://ftp.tu-chemnitz.de/pub/linux/dag/redhat/el6/en/x86_64/rpmforge/rpms/nettle-2.2-1.el6.rf.x86_64.rpm
# wget http://ftp.tu-chemnitz.de/pub/linux/dag/redhat/el6/en/x86_64/rpmforge/rpms/nettle-devel-2.2-1.el6.rf.x86_64.rpm
2、安装
安装aria2时会提示
error: failed dependencies:
libnettle.so.4()(64bit) is needed by aria2-1.16.4-1.el6.rf.x86_64
所以，需要先安装nettle-2.2.1，依次执行以下安装命令即可：
# rpm -ivh nettle-2.2-1.el6.rf.x86_64.rpm
# rpm -ivh nettle-devel-2.2-1.el6.rf.x86_64.rpm
# rpm -ivh aria2-1.16.4-1.el6.rf.x86_64.rpm
3、测试（下载百度首页）
# aria2c http://www.baidu.com
原文链接：https://www.ssite.cn/2017/05/23/centos-6-5%e5%ae%89%e8%a3%85aria2/