cUrl does not use OS env vars to detect if proxy is needed to query outside local network.
It would be very useful to add Proxy Preferences (proxy URL, optional user/password, HTTP/SOCKS, exclusions) and use cUrl options to set up WAN connexions filtered by a proxy.

http://stackoverflow.com/questions/5211887/how-to-use-curl-via-a-proxy