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Created Aug 13, 2018
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GSoC 2018 Summary

nwpd is a userspace daemon for the Neighborhood Watch Protocol, an address resolution protocol for XIA. nwpd's consists of 8 main files:

  • config.c: Consists of function for reading configuration files, and command line options, and writing them to the global nwpd_config.

  • log.c: Functions for logging.

  • monitor.c: Implements the monitoring system. The main variable here is hosts_table, a hash table mapping Ethernet addresses to a host_clock structure, that stores a bunch of monitoring related data. Every given period of time (, monitor_start_ping_process will select a random host, and attempt to send it a ping packet. If the host doesn't receive an ack in a given amount of time (monitor.ack-timeout), monitor_on_ack_timeout will select investigate-neighbor-count hosts on the network, and send them investigative ping requests. Further, if no investigative ack is received in monitor.investigate-ack-timeout seconds, the offending host will be removed as a neighbor.

  • neigh.c: Contains the function modify_neighbor and modify_route, which help add and remove neighbor and route entries, respectively. A neighbor is a main route in the Ether principal module, while a route from an AD XID to an Ether XID.

  • nwp.c: Contains functions for reading and validating NWP structures from provided buffers.

  • rtnl.c: Helper rtnetlink functions for communicating with the XIA kernel. Uses libmnl.

  • timer.c: Helper functions for working with POSIX timers (SIGEV_THREAD).

  • nwpd.c: Functions for sending base NWP packets (announce, neighbor list), and listening on a hardware interface for NWP packets (ether_receiver).


nwpd can be configured either by command line options (a complete list of options available by typing nwpd -h), or a config file provided with the flag -c. An example config file is provided with the source code in the file example.conf.

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