mac系统问题和优化-openssl的更新问题

因为mac 现在主要用 LibreSSL，openssl的更新没有及时。

如果需要更新，可以用brew来安装 openssl，并将其设置为 系统默认的openssl。

cooldeMacBook-Pro:~ cool$ brew install openssl
Updating Homebrew...
==> Downloading https://homebrew.bintray.com/bottles/openssl-1.0.2p.el_capitan.bottle.tar.
######################################################################## 100.0%
==> Pouring openssl-1.0.2p.el_capitan.bottle.tar.gz
==> Caveats
A CA file has been bootstrapped using certificates from the SystemRoots
keychain. To add additional certificates (e.g. the certificates added in
the System keychain), place .pem files in
  /usr/local/etc/openssl/certs

and run
  /usr/local/opt/openssl/bin/c_rehash

openssl is keg-only, which means it was not symlinked into /usr/local,
because Apple has deprecated use of OpenSSL in favor of its own TLS and crypto libraries.

If you need to have openssl first in your PATH run:
  echo 'export PATH="/usr/local/opt/openssl/bin:$PATH"' >> ~/.bash_profile

For compilers to find openssl you may need to set:
  export LDFLAGS="-L/usr/local/opt/openssl/lib"
  export CPPFLAGS="-I/usr/local/opt/openssl/include"

==> Summary
?  /usr/local/Cellar/openssl/1.0.2p: 1,793 files, 12.2MB
cooldeMacBook-Pro:~ cool$ openssl version
OpenSSL 0.9.8zh 14 Jan 2016
cooldeMacBook-Pro:~ cool$ 

调用方法一：更新系统环境变量:

cooldeMacBook-Pro:~ cool$ echo 'export PATH="/usr/local/opt/openssl/bin:$PATH"' >> ~/.bash_profile
cooldeMacBook-Pro:~ cool$ source  ~/.bash_profile
cooldeMacBook-Pro:~ cool$ openssl version
OpenSSL 1.0.2p  14 Aug 2018

调用方法二：

1、删除了.bash_profile中 的用户配置路径 openssl，
2、找到系统 /usr/bin/openssl 重命名乱连接，做备份 /usr/bin/openssl.bak
3、查看 新版openssl的安装目录：

cooldeMacBook-Pro:~ cool$ ls -l /usr/local/opt/openssl
lrwxr-xr-x  1 cool  admin  24 Oct 29 21:06 /usr/local/opt/openssl -> ../Cellar/openssl/1.0.2p

4、备份原来的/usr/bin/openssl，并重新设置系统openssl的软连接：

cooldeMacBook-Pro:~ cool$ sudo ln -s  /usr/local/Cellar/openssl/1.0.2p/bin/openssl  /usr/bin/openssl 
Password:
cooldeMacBook-Pro:~ cool$

关于python中的 ssl版本问题：

urllib是Python自带的标准库，无需安装，直接可以用。而urllib 是python自带的标准库，里面有ssl模块。也就是说python自带的的ssl模块与系统的openssl软件是无关的，版本号当然可以不相同。

cooldeMacBook-Pro:~ cool$ python -c "import ssl; print(ssl.OPENSSL_VERSION)"
OpenSSL 0.9.8zh 14 Jan 2016
cooldeMacBook-Pro:~ cool$ python
Python 2.7.10 (default, Oct 23 2015, 19:19:21) 
[GCC 4.2.1 Compatible Apple LLVM 7.0.0 (clang-700.0.59.5)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import ssl
>>> ssl.OPENSSL_VERSION
'OpenSSL 0.9.8zh 14 Jan 2016'
>>>

所以使用 旧版本的 urllib 库的 爬虫只支持ssl 1.0协议，导致ssl高版本协议的服务器拒绝与其连接。

HTTP exception InvalidCertificateException (Host codeload.github.com returned an invalid certificate ([SSL: TLSV1_ALERT_PROTOCOL_VERSION] tlsv1 alert protocol version (_ssl.c:548))) downloading https://codeload.github.com/seanliang/ConvertToUTF8/zip/1.2.11.