背景

有使用较老的Centos 5 系统内部安装软件无法正常报错，是由于系统叫老yum源存在问题

处理方法

更换下述yum源，可以将其他repo源文件备份移动到其他目录，添加下述源后重新测试

[C5.11-base]

name=CentOS-5.11   

baseurl=http://vault.centos.org/5.11/os/$basearch/gpgcheck=1

#gpgkey= file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-5    如果出现下述报错将此行注释

enabled=1

临时解决就是换个不同的镜像，比如：

baseurl= http://archive.kernel.org/centos-vault/5.11/os/$basearch/

如果出现下述报错提示：

result = func(*args)

  File "/usr/lib64/python2.4/urllib2.py", line 565, in http_error_302

    return self.parent.open(new)

  File "/usr/lib64/python2.4/urllib2.py", line 358, in open

    response = self._open(req, data)

  File "/usr/lib64/python2.4/urllib2.py", line 376, in _open

    '_open', req)

  File "/usr/lib64/python2.4/urllib2.py", line 337, in _call_chain

    result = func(*args)

  File "/usr/lib64/python2.4/site-packages/M2Crypto/m2urllib2.py", line 82, in https_open

    h.request(req.get_method(), req.get_selector(), req.data, headers)

  File "/usr/lib64/python2.4/httplib.py", line 810, in request

    self._send_request(method, url, body, headers)

  File "/usr/lib64/python2.4/httplib.py", line 833, in _send_request

    self.endheaders()

  File "/usr/lib64/python2.4/httplib.py", line 804, in endheaders

    self._send_output()

  File "/usr/lib64/python2.4/httplib.py", line 685, in _send_output

    self.send(msg)

  File "/usr/lib64/python2.4/httplib.py", line 652, in send

    self.connect()

  File "/usr/lib64/python2.4/site-packages/M2Crypto/httpslib.py", line 55, in connect

    sock.connect((self.host, self.port))

  File "/usr/lib64/python2.4/site-packages/M2Crypto/SSL/Connection.py", line 174, in connect

    ret = self.connect_ssl()

  File "/usr/lib64/python2.4/site-packages/M2Crypto/SSL/Connection.py", line 167, in connect_ssl

    return m2.ssl_connect(self.ssl, self._timeout)

M2Crypto.SSL.SSLError: unknown protocol

参考：

https://bugs.centos.org/view.php?id=18345

修改成如下信息：

[root@xxxx  yum.repos.d]# cat CentOS-Base.repo

[5.11-base]

name=CentOS-5.11 - Base

#baseurl=http://vault.centos.org/5.11/os/$basearch/gpgcheck=1

baseurl= http://archive.kernel.org/centos-vault/5.11/os/$basearch/

gpgcheck=1

#gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-5

enabled=1