no_networkparser option is set to
False(obviously, network access is blocked by default).
I commented on this on the lxml mailing list in 2008 when there was a discussion about high web traffic at the W3C due to excessive DTD loading, which was also attributed to parts of the Python standard library.
The right way to handle this (in general, but especially for lxml) is to configure the XML catalogs on the local system. The libxml2 site has some documentation on how to do this. The advantage of using catalogs is that most XML tools will use them when available, so it is a system wide fix for the problem. Most Linux installations come with readily configured XML catalogs, but other systems may have to get fixed up.