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Dnstap streams receiver

Testing Build Pypi Dockerhub

License: MIT PyPI - Python Version

This Python module acts as a dnstap streams receiver for DNS servers. Input streams can be a unix, tcp or raw socket. The output is printed directly on stdout or sent to remote tcp address in JSON, YAML or one line text format and more.

If you want better performance, please to use the dnscollector tool written in Go.

Table of contents

Installation

PyPI

Deploy the dnstap receiver in your DNS server with the pip command.

pip install dnstap_receiver

After installation, you can execute the dnstap_receiver to start-it.

Usage:

usage: dnstap_receiver [-h] [-l L] [-p P] [-u U] [-v] [-c C]

optional arguments:
  -h, --help  show this help message and exit
  -l L        IP of the dnsptap server to receive dnstap payloads (default: '0.0.0.0')
  -p P        Port the dnstap receiver is listening on (default: 6000)
  -u U        read dnstap payloads from unix socket
  -v          verbose mode
  -c C        external config file

Docker Hub

Pull the dnstap receiver image from Docker Hub.

docker pull dmachard/dnstap-receiver:latest

Deploy the container

docker run -d -p 6000:6000 -p 8080:8080 --name=dnstap01 dmachard/dnstap-receiver

Add the following argument to your container if you want to provide your own configuration file.

-v /home/dnstap.conf:/etc/dnstap_receiver/dnstap.conf

Follow containers logs

docker logs dnstap01 -f

Inputs handler

Severals inputs handler are supported to read incoming dnstap messages:

TCP socket (server)

The TCP socket input enable to receive dnstap messages from multiple dns servers. This is the default input if you execute the binary without arguments. The receiver is listening on localhost interface and the tcp port 6000. You can change binding options with -l and -p arguments.

./dnstap_receiver -l 0.0.0.0 -p 6000

You can also activate TLS on the socket, add the following config as external config file to activate the tls support, configure the path of the certificate and key to use.

input:
  tcp-socket:
    # enable tls support
    tls-support: true
    # provide certificate server path
    tls-server-cert: /etc/dnstap_receiver/server.crt
    # provide certificate key path
    tls-server-key: /etc/dnstap_receiver/server.key

Then execute the dnstap receiver with the configuration file:

./dnstap_receiver -c /etc/dnstap-receiver/dnstap.conf

TCP socket (client)

The TCP socket input enable to receive dnstap messages from remote dns servers. The communication is initiated by the dnstap receiver.

Configure this input as below

input:
  # tcp client
  tcp-client:
    # enable or disable
    enable: true
    # retry interval in seconds to connect
    retry: 1
    # remote dns server address
    remote-address: 10.0.0.2
    # remote dns server port
    remote-port: 6000

Unix socket

The unix socket input enables read dnstap message from a unix socket. Configure the path of the socket with the -u argument.

./dnstap_receiver -u /var/run/dnstap.sock

Raw socket (sniffer)

This input enable to sniff a network interface. Configure this input as below, you need to provide the name of your interface and associated ip.

input:
  # sniff dns messages from network interface 
  sniffer:
    # enable or disable
    enable: true
    # interface name to sniff
    eth-name: ens18
    # ip interface to sniff
    eth-ip: [ 10.0.0.2 ]
    # dnstap identity
    dnstap-identity: sniffer
    # sniff on the list of dns port
    dns-port: [ 53 ]
    # record incoming dns client queries
    record-client-query: true
    # record outgoing dns client responses
    record-client-response: true

Outputs handler

Outputs handler can be configured to forward messages in several modes.

Stdout

This output enables to forward dnstap messages directly to Stdout. Add the following configuration as external config to activate this output:

output:
  stdout:
    # enable or disable
    enable: true
    # format available text|json|yaml
    format: text

Output can be formatted in different way:

  • text (default one)
  • json
  • yaml

Text format:

2020-09-16T18:51:53.547352+00:00 lb1 CLIENT_QUERY NOERROR - - INET UDP 43b ns2.google.com. A -
2020-09-16T18:51:53.591736+00:00 lb2 CLIENT_RESPONSE NOERROR - - INET UDP 59b ns2.google.com. A 0.048

JSON format:

{
    "identity": "lb1",
    "qname": "www.google.com.",
    "rrtype": "A",
    "query-ip": "192.168.1.114",
    "message": "CLIENT_QUERY",
    "family": "INET",
    "protocol": "UDP",
    "query-port": 42222,
    "length": 43,
    "timestamp": "2020-09-16T18:51:53.591736+00:00",
    "rcode": "NOERROR",
    "id": 33422,
    "flags": "RD",
    "latency": "-"
}

YAML format:

identity: lb1
rcode: NOERROR
length: 49
message: CLIENT_QUERY
family: INET
qname: dns4.comlaude-dns.eu.
rrtype: AAAA
query-ip: '-'
query-port: '-'
timestamp: '2020-09-16T18:51:53.591736+00:00'
protocol: UDP
id: 33422
flags: RD
latency: '-'

File

This output enables to forward dnstap messages directly to a log file. Add the following configuration as external config to activate this output:

  # forward to log file
  file:
    # enable or disable
    enable: true
    # format available text|json|yaml
    format: text
    # log file path or null to print to stdout
    file: /var/log/dnstap.log
    # max size for log file
    file-max-size: 10M
    # number of max log files
    file-count: 10

If you are running the dnstap in a container, follow this procedure to save logs in your host instead of the container.

First one, create the folder in the host:

mkdir /var/dnstap/
chown 1000:1000 /var/dnstap/

Create the following configuration for your dnstap receiver

trace:
    verbose: true
output:
  stdout:
    enable: false
  file:
    enable: true
    format: text
    file: /home/dnstap/logs/dnstap.log
    file-max-size: 10M
    file-count: 10

Then execute the container with volume

docker run -d -p 6000:6000 -p 8080:8080 -v ${PWD}/dnstap.conf:/etc/dnstap_receiver/dnstap.conf \
-v /var/dnstap:/home/dnstap/logs/ --name=dnstap01 dmachard/dnstap-receiver

TCP

This output enables to forward dnstap message to a remote tcp collector. Add the following configuration as external config to activate this output:

output:
  # forward to remote tcp destination
  tcp-socket:
    # enable or disable
    enable: true
    # format available text|json|yaml
    format: text
    # delimiter
    delimiter: "\n"
    # retry interval in seconds to connect
    retry: 5
    # remote ipv4 or ipv6 address
    remote-address: 10.0.0.2
    # remote tcp port
    remote-port: 8192

Syslog

This output enables to forward dnstap message to a syslog server. Add the following configuration as external config to activate this output:

output:
  syslog:
    # enable or disable
    enable: false
    # syslog over tcp or udp
    transport: udp
    # format available text|json
    format: text
    # retry interval in seconds to connect
    retry: 5
    # remote ipv4 or ipv6 address of the syslog server
    remote-address: 10.0.0.2
    # remote port of the syslog server
    remote-port: 514

Example of output on syslog server

Sep 22 12:43:01 bind CLIENT_RESPONSE NOERROR 192.168.1.100 51717 INET UDP 173b www.netflix.fr. A 0.040
Sep 22 12:43:01 bind CLIENT_RESPONSE NOERROR 192.168.1.100 51718 INET UDP 203b www.netflix.fr. AAAA 0.060

Metrics

This output enables to generate metrics in one line and print-it to stdout. Add the following configuration as external config to activate this output:

output:
  metrics:
    # enable or disable
    enable: true
    # print every N seconds.
    interval: 300
    # cumulative statistics, without clearing them after printing
    cumulative: true
    # log file path or null to print to stdout
    file: null
    # max size for log file
    file-max-size: 10M
    # number of max log files
    file-count: 10

Example of output

2020-10-13 05:19:35,522 18 QUERIES, 3.6 QPS, 1 CLIENTS, 18 INET, 0 INET6, 
18 UDP, 0 TCP, 17 DOMAINS

Dnstap

This output enables to send dnstap messages to a remote dnstap receiver. Add the following configuration as external config to activate this output:

  # forward to another remote dnstap receiver
  dnstap:
    # enable or disable
    enable: true
    # retry interval in seconds to connect
    retry: 1
    # remote ipv4 or ipv6 address of the remote dnstap receiver
    remote-address: 10.0.0.51
    # remote port of the remote dnstap receiver
    remote-port: 6000
    # dnstap identity
    dnstap-identity: dnstap-receiver

Kafka

This output enables to send dnstap messages to a Kafka topic.

Install extra python library for kafka

pip install dnstap_receiver[kafka]

Configuration

  # forward to a Kafka topic
  kafka:
    # enable or disable
    enable: false
    # format available text|json|yaml
    format: json
    # configuration object to pass to librdkafka
    rdkafka-config:
      "bootstrap.servers": null
      "security.protocol": null
      "sasl.mechanism": null
      "sasl.username": null
      "sasl.password": null
    # Kafka topic to forward messages to
    topic: null

PostgreSQL

This output enables to send dnstap messages to a PostgreSQL.

Install extra python library for PostgreSQL (asyncpg).

See output_pgsql_userfunc.py to replace table definition and data insertion.

pip install dnstap_receiver[pgsql]

Configuration

  # forward to postgresql server
  pgsql:
    # enable or disable
    enable: false
    # retry interval in seconds to connect
    retry: 1
    # dsn := postgres://user@host:port/database
    # To explicitly write passwd in dsn is not recommended though possible.
    # Instead use passfile below.
    dsn: postgres://postgres@localhost:5432/postgres
    # passfile := /path/to/.pgpass
    # https://www.postgresql.org/docs/12/libpq-connect.html#LIBPQ-CONNECT-PASSFILE
    passfile: ~/.pgpass
    # min_size: minimum number of connections in the pool
    min_size: 5
    # max_size: maximum number of connections in the pool
    max_size: 10
    # busy_wait: wait this amount of seconds in the busy loop to write to PostgreSQL.
    busy_wait: 1.0
    # timeout: wait this amount of seconds to re-create the connection pool to PostgreSQL after it failed.
    timeout: 60
    # filename including user defined functions
    userfuncfile: null

More options

External config file

The dnstap_receiver binary can takes an external config file with the -c argument or searches for a config file named dnstap.conf in /etc/dnstap_receiver/.

See config file example.

./dnstap_receiver -c /etc/dnstap-receiver/dnstap.conf

Verbose mode

You can execute the binary in verbose mode with the -v argument:

./dnstap_receiver -v
2020-11-25 20:26:59,790 DEBUG Start receiver...
2020-11-25 20:26:59,790 DEBUG Output handler: stdout
2020-11-25 20:26:59,790 DEBUG Input handler: tcp socket
2020-11-25 20:26:59,790 DEBUG Input handler: listening on 0.0.0.0:6000
2020-11-25 20:26:59,790 DEBUG Api rest: listening on 0.0.0.0:8080

Filtering feature

This feature can be useful if you want to ignore some messages and keep just what you want. Several filter are available:

  • by qname field
  • by dnstap identity field.

By dnstap identity

You can filtering incoming dnstap messages according to the dnstap identity field. A regex can be configured in the external configuration file to do that

filter:
  # dnstap identify filtering feature with regex support
  dnstap-identities: dnsdist01|unbound01

By qname

You can filtering incoming dnstap messages according to the query name. A regex can be configured in the external configuration file to do that

filter: 
  # qname filtering feature with regex support
  qname-regex: ".*.com"

GeoIP support

The dnstap receiver can be extended with GeoIP. To do that, you need to configure your own city database in binary format.

# geoip support, can be used to get the country, and city
# according to the source ip in the dnstap message
geoip:
    # enable or disable
    enable: true
    # city database path in binary format
    city-database: /var/geoip/GeoLite2-City.mmdb
    # represent country in iso mode
    country-iso: false

With the GeoIP support, the following new fields will be added:

  • country
  • city

Statistics

Some statistics are computed on the fly and stored in memory, you can get them:

Counters

  • query: number of queries
  • response: number of answers
  • qps: number of queries per second
  • clients: number of unique clients ip
  • domains: number of unique domains
  • query/inet: number of IPv4 queries
  • query/inet6: number of IPv6 queries
  • response/inet: number of IPv4 answers
  • response/inet6: number of IPv6 answers
  • query/udp: number of queries with UDP protocol
  • query/tcp: number of queries with TCP protocol
  • response/udp: number of answers with UDP protocol
  • response/tcp: number of answers with TCP protocol
  • response/[rcode]: number of answers per specific rcode = noerror, nxdomain, refused,...
  • query/[rrtype]: number of queries per record resource type = = a, aaaa, cname,...
  • query/bytes: total number of bytes with queries
  • response/bytes: total number of bytes with answers
  • response/latency0_1: number of queries answered in less than 1ms
  • response/latency1_10: number of queries answered in 1-10 ms
  • response/latency10_50: number of queries answered in 10-50 ms
  • response/latency50_100: number of queries answered in 50-100 ms
  • response/latency100_1000: number of queries answered in 100-1000 ms
  • response/latency_slow: number of queries answered in more than 1 second

Tables

  • tlds:
    • hit/query: table of [n] tlds sorted by number of queries
    • hit/response: table of [n] tlds sorted by number of answers
  • domains:
    • [rcode]/query: table of [n] domains sorted by number of queries
    • [rcode]/response: table of [n] domains sorted by number of answers
  • clients:
    • hit/client: table of [n] ip addresses sorted by number of queries
    • length/ip: table of [n] ip addresses sorted by number of bytes
  • rrtypes
    • hit/query: table of [n] resources record types sorted by the number of queries
    • hit/response: table of [n] resources record types sorted by the number of answers
  • top-rcodes:
    • hit/query: table of [n] return codes sorted by the number of queries
    • hit/response: table of [n] return codes sorted by the number of answers

Metrics

Metrics in Prometheus format with global counters and specific by dnstap stream.

See metrics file example.

# HELP dnstap_queries Number of queries received
# TYPE dnstap_queries counter
dnstap_queries 0
# HELP dnstap_responses Number of responses received
# TYPE dnstap_responses counter
dnstap_responses 0
# HELP dnstap_responses_noerror Number of NOERROR answers
# TYPE dnstap_responses_noerror counter
dnstap_responses_noerror 0
# HELP dnstap_responses_nxdomain Number of NXDomain answers
# TYPE dnstap_responses_nxdomain counter
dnstap_responses_nxdomain 0
# HELP dnstap_responses_servfail Number of SERVFAIL  answers
# TYPE dnstap_responses_servfail counter
dnstap_responses_servfail 0
...

Build-in Webserver

The build-in web server can be used to get statistics computed by the dnstap receiver.

Configuration

Enable the HTTP API, don't forget to change the default password.

# rest api
web-api:
    # enable or disable
    enable: true
    # web api key
    api-key: changeme
    # basicauth login
    login: admin
    # basicauth password
    password: changeme
    # listening address ipv4 0.0.0.0 or ipv6 [::]
    local-address: 0.0.0.0
    # listing on port
    local-port: 8080

Security

The following authentication methods are supported:

  • BasicAuth
  • X-API-Key

To access to the API, one of them method must be used in the request header. An HTTP 401 response is returned when the authentication failed.

HTTP API

See the swagger documentation.

Benchmark

Limited lab

Tested on a limited lab with the following processor: Intel Core i5-7200U @2,50GHz

Metrics are extracted every second:

watch -n 1 "time curl --user admin:changeme http://[ip_dnstap_receiver]:8080/metrics"

Dns generator used:

docker pull ns1labs/flame
docker run ns1labs/flame [ip_dns_server]

Result:

Parameters Values
Query per seconds ~11000
Domains ~40000
Clients 1
CPU usage ~30%
Memory usage ~100Mo
Network usage ~5.7Mb

Development

Run

the dnstap receiver from source

python3 -c "from dnstap_receiver.receiver import start_receiver; start_receiver()" -v

Testunits

python3 -m unittest tests.test_receiver_tcpsocket -v

About

Author Denis Machard d.machard@gmail.com
PyPI https://pypi.org/project/dnstap-receiver/
Github https://github.com/dmachard/dnstap-receiver
DockerHub https://hub.docker.com/r/dmachard/dnstap-receiver