.. _`Cisco Discovery Protocol`: https://en.wikipedia.org/wiki/Cisco_Discovery_Protocol
.. _ddclient: https://sourceforge.net/p/ddclient/wiki/Home/
.. _`Foundry Discovery Protocol`: https://en.wikipedia.org/wiki/Foundry_Discovery_Protocol
.. _MIB: https://en.wikipedia.org/wiki/Management_information_base
.. _SNMP: https://en.wikipedia.org/wiki/Simple_Network_Management_Protocol
.. _SNMPv2: https://en.wikipedia.org/wiki/Simple_Network_Management_Protocol#Version_2
.. _SNMPv3: https://en.wikipedia.org/wiki/Simple_Network_Management_Protocol#Version_3
.. _SSH: https://en.wikipedia.org/wiki/Secure_Shell
.. _Squid3: http://www.squid-cache.org/
.. _Squidguard: http://www.squidguard.org/
.. _TFTP: https://en.wikipedia.org/wiki/Trivial_File_Transfer_Protocol
.. _`arbitrary extension commands`: http://net-snmp.sourceforge.net/docs/man/snmpd.conf.html#lbAZ
.. _`accel-ppp`: https://accel-ppp.org/
.. _`Secure Socket Tunneling Protocol`: https://en.wikipedia.org/wiki/Secure_Socket_Tunneling_Protocol