To use libz functions, I add : #include <zlib.h> #include <zutil.h> in http.c But it doesn't work! There seems to be a problem with the zlib function "deflate" My logs : Jun 12 09:41:41 bridge zorp_http[13743]: (zorp@site/intra_http:1/http): Proxy starting; class='IntraHttp', module='http' Jun 12 09:41:41 bridge zorp_http[13743]: (noname/nosession): Module loading failed; module='http', file='/usr/local/lib/zorp/libhttp.so', error='/usr/local/lib/zorp/libhttp.so: undefined symbol: deflate' Jun 12 09:41:41 bridge zorp_http[13743]: (noname/nosession): Cannot find proxy module; module='http' type='1' Jun 12 09:41:41 bridge zorp_http[13745]: (Log thread): Traceback (most recent call last): Jun 12 09:41:41 bridge zorp_http[13745]: (Log thread): File "/usr/local/share/zorp/pylib/Zorp/Dispatch.py", line 173, in accepted Jun 12 09:41:41 bridge zorp_http[13745]: (Log thread): return session.service.startInstance(session) Jun 12 09:41:41 bridge zorp_http[13745]: (Log thread): File "/usr/local/share/zorp/pylib/Zorp/Service.py", line 258, in startInstance Jun 12 09:41:41 bridge zorp_http[13745]: (Log thread): proxy = self.proxy_class(ss) Jun 12 09:41:41 bridge zorp_http[13745]: (Log thread): File "/usr/local/share/zorp/pylib/Zorp/Http.py", line 582, in __init__ Jun 12 09:41:41 bridge zorp_http[13745]: (Log thread): Proxy.__init__(self, session) Jun 12 09:41:41 bridge zorp_http[13745]: (Log thread): File "/usr/local/share/zorp/pylib/Zorp/Proxy.py", line 96, in __init__ Jun 12 09:41:41 bridge zorp_http[13745]: (Log thread): ZorpProxy.__init__(self, self.name, session.session_id, session.client_stream) Jun 12 09:41:41 bridge zorp_http[13745]: (Log thread): RuntimeError: Error loading proxy module.