How to suppress a third-party warning using warnings.filterwarnings

Easiest way would be as the warnings module suggests here:

with warnings.catch_warnings():
    warnings.simplefilter("ignore")
    import paramiko

The module argument to warnings.filterwarnings takes a case-sensitive regular expression which should match the fully qualified module name, so

warnings.filterwarnings(
    action='ignore',
    category=DeprecationWarning,
    module=r'.*randpool'
)

or

warnings.filterwarnings(
    action='ignore',
    category=DeprecationWarning,
    module=r'Crypto\.Utils\.randpool'
)

should work. You may need to write RandomPool_DeprecationWarning explicitly instead of DeprecationWarning if for some reason RandomPool_DeprecationWarning is not a subclass of DeprecationWarning.

You can also disable the warning on the command line when you invoke the script by passing the -W option to the interpreter like so:

$ python -W ignore::RandomPool_DeprecationWarning:Crypto.Utils.randpool: my_script.py

The -W takes filters in the format action:message:category:module:lineno, where this time module must exactly match the (fully-qualified) module name where the warning is raised.

See https://docs.python.org/2/library/warnings.html?highlight=warnings#the-warnings-filter and https://docs.python.org/2/using/cmdline.html#cmdoption-w

To filter only a specific warning:

with warnings.catch_warnings():
    warnings.simplefilter('ignore', SpecificWarningObject)

    #do something that raises a Warning

The most flexible way is to combine warnings.filterwarnings() with the warnings.catch_warnings() context manager. This way you ge the flexibility of filterwarnings but the filtering is only applied inside the with block:

import warnings
from Crypto.pct_warnings import RandomPool_DeprecationWarning

with warnings.catch_warnings():
    warnings.filterwarnings(
        action='ignore',
        category=RandomPool_DeprecationWarning,
        message='This application uses RandomPool, which is BROKEN in older releases')
   
    # Do stuff that causes the warning