# DNS Replay Tool (drool)

`drool` can replay DNS traffic from packet capture (PCAP) files and send
it to a specified server, with options such as to manipulate the timing
between packets, as well as loop packets infinitely or for a set number
of iterations. This tool's goal is to be able to produce a high amount
of UDP packets per second and TCP sessions per second on common hardware.

The purpose can be to simulate Distributed Denial of Service (DDoS) attacks
on the DNS and measure normal DNS querying. For example, the tool could
enable you to take a snapshot of a DDoS and be able to replay it later
to test if new code or hardening techniques are useful, safe & effective.
Another example is to be able to replay a packet stream for a
bug that is sequence- and/or timing-related in order to validate the
efficacy of subsequent bug fixes.

More information may be found here:
- https://www.dns-oarc.net/tools/drool

Issues should be reported here:
- https://github.com/DNS-OARC/drool/issues

General support and discussion:
- Mattermost: https://chat.dns-oarc.net/community/channels/oarc-software

## Known Issues

- IP fragments are currently not processed and will be discarded.
- TCP sessions are not reassembled, each packet is parsed as DNS after
  discarding the first two bytes.

## Usage example

Send all DNS queries twice as fast as found in the PCAP file to localhost
using UDP.

```shell
drool replay --timing multiply=0.5 --no-tcp file.pcap 127.0.0.1 53
```

Send all DNS queries over TCP to localhost as they were recorded.

```shell
drool replay --timing keep --no-udp file.pcap 127.0.0.1 53
```

Take all DNS queries found in the PCAP file and send them as fast as possible
over UDP to localhost by ignoring both timings, replies and starting 3 threads
that will simultaneously send queries.

```shell
drool replay --no-tcp --no-responses --threads --udp-threads 3 file.pcap 127.0.0.1 53
```

## Dependencies

`drool` is built upon [dnsjit](https://github.com/DNS-OARC/dnsjit) and
requires it to be installed along with autoconf/automake.

## Build

```
sh autogen.sh
./configure
make
make test
make install
```

## Author(s)

Jerry Lundström <jerry@dns-oarc.net>

## Copyright

Copyright (c) 2017-2021, OARC, Inc.

Copyright (c) 2017, Comcast Corporation

All rights reserved.

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