编辑 /etc/apt/sources.list 加上
deb http://ftp.es.debian.org/debian stable main contrib non-free
deb-src http://ftp.es.debian.org/debian stable main contrib non-free
deb http://ftp.debian.org/debian/ wheezy-updates main contrib non-free
deb-src http://ftp.debian.org/debian/ wheezy-updates main contrib non-free
deb http://security.debian.org/ wheezy/updates main contrib non-free
deb-src http://security.debian.org/ wheezy/updates main contrib non-free执行下面的命令
sudo apt-get update
sudo apt-get install libapache2-mod-php5