执行 hadoop checknative 报错 openssl: false Cannot load libcrypto.so

部署完Hadoop之后，执行 hadoop checknative 对本地库做检查，执行结果为

17/02/09 10:02:41 WARN bzip2.Bzip2Factory: Failed to load/initialize native-bzip2 library system-native, will use pure-Java version
17/02/09 10:02:41 INFO zlib.ZlibFactory: Successfully loaded & initialized native-zlib library
Native library checking:
hadoop:  true /home/user/tool/hadoop-2.7.3/lib/native/libhadoop.so
zlib:    true /lib/x86_64-linux-gnu/libz.so.1
snappy:  false 
lz4:     true revision:99
bzip2:   false 
openssl: false Cannot load libcrypto.so (libcrypto.so: cannot open shared object file: No such file or directory)!

提示不能正确加载 libcrypto.so，查了下是因为缺少 ssl lib包；于是执行命令 

apt-get install libssl-dev

等待安装完毕后，执行 hadoop checknative ，不再提示 Cannot load libcrypto.so的错误了，出现跟官网一样的提示信息：

user@ubuntu:~/tool/hadoop$ bin/hadoop checknative
17/02/09 10:04:09 WARN bzip2.Bzip2Factory: Failed to load/initialize native-bzip2 library system-native, will use pure-Java version
17/02/09 10:04:09 INFO zlib.ZlibFactory: Successfully loaded & initialized native-zlib library
Native library checking:
hadoop:  true /home/user/tool/hadoop-2.7.3/lib/native/libhadoop.so
zlib:    true /lib/x86_64-linux-gnu/libz.so.1
snappy:  false 
lz4:     true revision:99
bzip2:   false 
openssl: true /usr/lib/x86_64-linux-gnu/libcrypto.so