python xmlrpc client with ssl client certificates and standard modules

[News123]

Hi,

I was googling fot quite some time and was not really succesfull.

I found one solution, which I will try soon.
It is
http://www.cs.technion.ac.il/~danken/xmlrpc-ssl.html
(found in
http://hamakor.org.il/pipermail/python-il/2008-February/000029.html )

This will probably work, but it requires the module M2Crypto.

In order to avoid installing M2Crypto an all hosts that want to run the
script I wondered, whether there is no other solution.

I can do xmlrpc over ssl WITHOUT certificates with following code:

import xmlrpclib
server_url = 'https://myserver'
server = xmlrpclib.Server(server_url);


and I can perform a https get request WITH certificates with below snippet:

import httplib
conn = httplib.HTTPSConnection(
HOSTNAME,
key_file = KEYFILE,
cert_file = CERTFILE
)
conn.putrequest('GET', '/')
conn.endheaders()
response = conn.getresponse()
print response.read()


I'm just lost of how to 'combine' both.


Thanks in advance for any suggestions / hints




N

 

[mdipierro]

xmlrpc acts at the application layer and ssl at the transport layer so
they can inter operate easily as long as you do not use the
certificate to authenticate the client but only validate the server
and encrypt data (which you can also do but it is more complicated)

One option for you is to use web2py which include an xmlrpc server
that uses a wsgi ssl enabled web server.

Here is how:

1) Install web2py
2) Visit http://127.0.0.1:8000/admin and create a new application from
the web based IDE
3) create your web service for example, in a controller default.py

@service.xmlrpc
def add(a,b): return int(a)+int(b)

4) Restart web2py with

python web2py.py -a ADMIN_PASSWD -c SSL_CERTIFICATE -k
SSL_PRIVATE_KEY -i 0.0.0.0 -p 443

5) You can now access the service from any Python program:
7

Hope this helps.

 

[News123]

Thanks for your answer.


I'll look at web2py.

However web2py seems to address the xmlrpc server (at least in your
example). The xmlrpc server application exists alerady and requires a
client certificate.

The client example doesn't seem to be using a certificate.

So I'll be reading a little into web2py.


bye


N

 

[mdipierro]

If it is a client problem than web2py will be on help.

If your server is written already you may be able to use it with the
ssl cherrypy wsgi server (the one that web2py uses) and you do not
need web2py at all.

Massimo

 

[News123]

Hi Massimo,


I'm still a litle confused:

My setup:

server host:
------------
apache, php with an xmlrpc server interface.
no python installed.


multiple client hosts (linux / windows only default python installed)
-----------------------------------------------------------------------
an existing python script performing an xmlrpc call to the server host.
The current working (without certificates) code snippet is:

import xmlrpclib
server_url = 'https://myserver'
server = xmlrpclib.Server(server_url);
result = server.myfunction(args)





The whole setup is working as long as no client certificates are imposed
by the server.
The whole setup is not working as soon as the server is configured to
accept only a given set of SSL-client certificates.



My question is how to change above four line code snippet, such, that a
client certificate will be sent to the xmlrpc server
asuming the variables
CLIENT_KEY_FILE and CLIENT_CRT_FILE are defined and pointing to the
client certificate files.


I hope to have more time tomorrow to check out the option,
that I found and the option, that you suggest.

option 1:
http://www.cs.technion.ac.il/~danken/xmlrpc-ssl.html
( with non standard py module M2Crypto )

option 2:
or web2py, which at first (so far no second) glance seems more
to be targeted at implementing server side application with ajax
or the client side.


thanks again and bye


N

 

[Martin v. Loewis]

I can do xmlrpc over ssl WITHOUT certificates with following code:

import xmlrpclib
server_url = 'https://myserver'
server = xmlrpclib.Server(server_url);


and I can perform a https get request WITH certificates with below snippet:

import httplib
conn = httplib.HTTPSConnection(
HOSTNAME,
key_file = KEYFILE,
cert_file = CERTFILE
)
conn.putrequest('GET', '/')
conn.endheaders()
response = conn.getresponse()
print response.read()


I'm just lost of how to 'combine' both.

In this case, read through the source of xmlrpclib:

a) SafeTransport receives x509 parameters from get_host_info
b) get_host_info supports a case where host is a tuple host, x509

So, without testing:

server = xmlrpclib.Server((server_url, {'key_file': KEYFILE,
'cert_file': CERTFILE}))

Please do read the code before trying this out.

HTH,
Martin

 

[News123]

Hi Martin,

Thanks a lot for your reply.
It helped me to find the correct solution.

Unfortunaltely xmlrpclib.ServerProxy does not allow a host tuple, but
just a uri.

So the simplest solution, that I found is to create a custom transport


import xmlrpclib

class SafeTransportWithCert(xmlrpclib.SafeTransport):
__cert_file = DFLT_CERTFILE
__key_file = DFLT_KEYFILE
def make_connection(self,host):
host_with_cert = (host, {
'key_file' : self.__key_file,
'cert_file' : self.__cert_file
} )
return \
xmlrpclib.SafeTransport.make_connection(
self,host_with_cert)


transport = SafeTransportWithCert()
server = xmlrpclib.ServerProxy(server_url,
transport = transport)

rslt = server.mymethod(args)


Perfect.
Now the server can ensure, that only certified clients connect.

My next task is how to find out at the client side, that the server
certificate is a properly signed one.

bye


N

 

[Heikki Toivonen]

This will probably work, but it requires the module M2Crypto.

In order to avoid installing M2Crypto an all hosts that want to run the
script I wondered, whether there is no other solution.

I can do xmlrpc over ssl WITHOUT certificates with following code:

[...]

Please note that if you just use the stdlib it is not secure out of the
box. With Python 2.6 and the ssl module you can make it so, but it
requires some work on your part. See for example
http://www.heikkitoivonen.net/blog/2008/10/14/ssl-in-python-26/

 

[Martin v. Loewis]

My next task is how to find out at the client side, that the server

certificate is a properly signed one.

As Heikki says, you'll need Python 2.6 for that. You'll probably need to
extend your transport implementation.

Regards,
Martin

 

[vilas]

My question is to mdipierro.
I am using web2py. We have one web service in .NET. In order to access that service we need to pass certificate to that service. How do I do it in Web2py?
I have Windows 7 operating system and .cer certificate is installed on my machine. I am using pysimplesoap library but there is no provision given to send certificate. I have also tried your solution in this thread which is

python web2py.py -a ADMIN_PASSWD -c SSL_CERTIFICATE -k
SSL_PRIVATE_KEY -i 0.0.0.0 -p 443

as I have only one cer file I am using only that file here. But this is also not working and I am getting Forbidden error message here. Please help.