dnstop is a libpcap application (a la tcpdump) that displays
various tables of DNS traffic on your network. Currently dnstop
displays tables of:
* Source IP addresses
* Destination IP addresses
* Query types
* Response codes
* Opcodes
* Top level domains
* Second level domains
* Third level domains
* etc...
dnstop supports both IPv4 and IPv6 addresses.
To help find especially undesirable DNS queries, dnstop provides a
number of filters. The filters tell dnstop to display only the following
types of queries:
* For unknown/invalid TLDs
* A queries where the query name is already an IP address
* PTR queries for RFC1918 address space
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