UDP socket issue on unix - bind: address already in use

1....UDP socket issue on unix - bind: address already in use - ...

2.client send data OK,but server not receive data
but http://blog.csdn.net/u012234115/article/details/54142273 is OK

refer to http://bbs.csdn.net/topics/320080447
         http://bbs.csdn.net/topics/390219262
baidu:linux UDP client接收不到数据

问题记录，后续更新。。。