pip3安装库时报超时问题小结

在Linux测试服务器上使用pip3安装组件时，遇到下面错误：

#pip3 install cryptography

WARNING: Retrying (Retry(total=4, connect=None, read=None, redirect=None, status=None)) after connection broken by "ProxyError("Cannot connect to proxy.", timeout("timed out"))": /simple/cryptography/

WARNING: Retrying (Retry(total=3, connect=None, read=None, redirect=None, status=None)) after connection broken by "ProxyError("Cannot connect to proxy.", timeout("timed out"))": /simple/cryptography/

....................................

ERROR: Could not find a version that satisfies the requirement cryptography (from versions: none)

ERROR: No matching distribution found for cryptography