关于使用python Fabri时候包找不到，该怎么安装这个包

信息如下：

Traceback (most recent call last):
  File "/usr/lib/python2.6/site-packages/fabric/network.py", line 24, in 
    import paramiko as ssh
  File "/usr/lib/python2.6/site-packages/paramiko/__init__.py", line 30, in 
    from paramiko.transport import SecurityOptions, Transport
  File "/usr/lib/python2.6/site-packages/paramiko/transport.py", line 49, in 
    from paramiko.dsskey import DSSKey
  File "/usr/lib/python2.6/site-packages/paramiko/dsskey.py", line 26, in 
    from Crypto.PublicKey import DSA
ImportError: No module named Crypto.PublicKey

There was a problem importing our SSH library (see traceback above).
Please make sure all dependencies are installed and importable.

Crypto.PublicKey这个包应该怎么安装？