Here is a list of all documented namespaces with brief descriptions:

[detail level 12]

NBridgeInterface	A set of functions to setup and bring down a bridge device. The main reason to use these functions separately rather than direct calls to a netlink object from NetworkSetup.cpp is to provide workarounds for libnl versions 3.3.x - 3.4.x
NDnsmasqSetup	Sets up iptables routing to allow apps within a network namespace to talk to the dnsmasq server running outside the container
NInterContainerRouting	Used to add iptables firewall rules to allow a container to either expose a port to another container or to access a port on another container
NMulticastForwarderPlugin	Used to add iptables firewall rules, ebtables and smcroute rules to allow containered processes to receive multicast traffic
NNetworkSetup	Functions to set up networking for containers
NPortForwarding	Used to add iptables firewall rules to allow port forwarding between the container and the host
▼NPrivateInterface	Function: Contains the abstract public interface to interfaces (very meta)
CPrivateInterface	The PrivateInterface This provides a virtual destructor to interface
NTapInterface