1.在A执行：
- sudo apt-get install rpcbind nfs-kernel-server
- sudo iptables -I INPUT -s x.x.x.b -j ACCEPT
- echo "/p x.x.x.0/24(rw,sync,no_root_squash,no_subtree_check)" >> /ect/exports
- sudo exportfs -ra
- sudo service nfs-kernel-server start
2.在B执行：
如果不行，阅读原文：https://help.ubuntu.com/community/SettingUpNFSHowTo
- sudo apt-get isntall nfs-common
- sudo mount -t nfs x.x.x.a:/p /q
