DnsServer/Apps/QueryLogsPostgreSqlApp

Query Logs PostgreSQL App

A DNS App for Technitium DNS Server that logs DNS queries to a PostgreSQL database.

Overview

• Async logging – writes log entries through a bounded queue
• Cleanup support – prunes old records by age/count
• Retained schema – uses a database name and connection string for storage

Integration / extension points

• Implements: IDnsApplication, IDnsQueryLogger, IDnsQueryLogs
• Runs as a DNS query logger with asynchronous persistence.

Database

The database table stores values for some fields in numeric format. The fields and the values are described as below.

Protocol Field

Protocol	Value	Description
0	UDP	The standard DNS over UDP protocol
1	TCP	The standard DNS over TCP protocol
2	TLS	DNS-over-TLS RFC 7858
3	HTTPS	DNS-over-HTTPS RFC 8484
5	QUIC	DNS-over-QUIC RFC 9250
253	UdpProxy	PROXY Protocol over UDP
254	TcpProxy	PROXY Protocol over TCP

Response Type Field

Response Type	Value	Description
1	Authoritative	Response generated by the DNS server itself
2	Recursive	Response received from a recursive query to upstream
3	Cached	Response generated by DNS server's cache
4	Blocked	Response generated by DNS server to block a request
5	UpstreamBlocked	Response received from an upstream blocking a request
6	UpstreamBlockedCached	Response generated by DNS server's cache containing blocked response from upstream
7	Dropped	A null response generated by the DNS server indicating that the request was dropped

Configuration

dnsApp.config contains these keys:

Property	Type	Default	Description
enableLogging	boolean	false	Enables or disables query logging.
maxQueueSize	number	1000000	Maximum number of log entries allowed in the in-memory queue before new entries are dropped.
maxLogDays	number	0	Maximum age (days) to retain. 0 disables age-based cleanup.
maxLogRecords	number	0	Maximum number of records to retain. 0 disables count-based cleanup.
databaseName	string	"DnsQueryLogs"	Database name used to store logs.
connectionString	string	(required)	PostgreSQL connection string without the database name. The app appends Database={databaseName}; internally.

Example

{
  "enableLogging": false,
  "maxQueueSize": 1000000,
  "maxLogDays": 0,
  "maxLogRecords": 0,
  "databaseName": "DnsQueryLogs",
  "connectionString": "Server=192.168.180.128; Port=3306; Uid=username; Pwd=password;"
}

Runtime behavior

1. Queries are buffered in a bounded channel.
2. A background consumer thread bulk inserts records into PostgreSQL storage.
3. A periodic cleanup timer removes old records.

Risks / operational notes

• Queue overflow drops writes (DropWrite behavior).
• Database connectivity issues can stop logging.
• High traffic deployments should monitor write latency.

Troubleshooting

• Confirm the database is reachable and credentials are valid.
• Check the connection string and databaseName.
• Review server logs for SQL client errors.