This is Net-SNMP (previously known as "ucd-snmp").

Various tools relating to the Simple Network Management Protocol including: 

    An extensible agent 
    An SNMP library 
    tools to request or set information from SNMP agents 
    tools to generate and handle SNMP traps 
    a version of the unix 'netstat' command using SNMP 
    a graphical Perl/Tk/SNMP based mib browser

WWW: http://net-snmp.sourceforge.net/