dnsfilexfer - File transfers via DNS

Just some code to xfer files via DNS lookups. Supports encrypting the on the wire traffic with a short passphrase and can be used to be parsed purely from the output found in a tcpdump using xxd and the -X flag in the sender.

Installing

Clone the repo, and install the dependencies as put out in requirements.txt:

% git clone https://github.com/leonjza/dnsfilexfer.git
% cd dnsfilexfer
% sudo pip install -r requirements.txt

In case the installation fails because of pycrypto, you might need to install python-dev manually.

Sample Usage:

Assuming the receiver dns_recv.py is running (where 192.168.10.1 is the server):

% echo "This is a test message that will be sent over DNS\n Cool eh?" > /tmp/message
% cat /tmp/message
This is a test message that will be sent over DNS
Cool eh?

% python dns_send.py --server 192.168.10.1 --file /tmp/message --indentifier dns_message_test --secret
What is the secret?
[INFO] Message is encypted with the secret
---START OF MESSAGE---
/lHsvTZT3nJfQgdtUWSpKDqrpKuK+eLrU3bpAp9aNDJt6K/mwEc8sBUaJybPh7r5h2AOkJVezwBBODSV9hFM8w==
---END OF MESSAGE---
[INFO] Sending lookup for : 00006:10000000000000000000000000000000000000000000000000.fake.io
[INFO] Sending lookup for : 0001646e735f6d6573736167655f7465737400000000000000000000.fake.io
[INFO] Sending lookup for : 00028bf2046ae2144be75d2ce780b3f992e2c368021e.fake.io
[INFO] Sending lookup for : 00032f6c487376545a54336e4a6651676474555753704b447172704b754b.fake.io
[INFO] Sending lookup for : 00042b654c7255336270417039614e444a74364b2f6d7745633873425561.fake.io
[INFO] Sending lookup for : 00054a796250683772356832414f6b4a56657a7742424f4453563968464d.fake.io
[INFO] Sending lookup for : 000638773d3d.fake.io
[INFO] Sending lookup for : 00000000000000000000000000000000000000000000000000000000.fake.io
[INFO] Message sent in 8 requests

On the server/receiver

% sudo python dns_recv.py --listen 0.0.0.0 --secret
Password:
What is the secret?
[INFO] Fake DNS server listening on 0.0.0.0 / 53 with a configured secret.
[INFO] Full resource record query was for: 00006:10000000000000000000000000000000000000000000000000.fake.io.
[INFO] Processing frame 00006:10000000000000000000000000000000000000000000000000
[INFO] Full resource record query was for: 0001646e735f6d6573736167655f7465737400000000000000000000.fake.io.
[INFO] Processing frame 0001646e735f6d6573736167655f7465737400000000000000000000
[INFO] Full resource record query was for: 00028bf2046ae2144be75d2ce780b3f992e2c368021e.fake.io.
[INFO] Processing frame 00028bf2046ae2144be75d2ce780b3f992e2c368021e
[INFO] Full resource record query was for: 00032f6c487376545a54336e4a6651676474555753704b447172704b754b.fake.io.
[INFO] Processing frame 00032f6c487376545a54336e4a6651676474555753704b447172704b754b
[INFO] Full resource record query was for: 00042b654c7255336270417039614e444a74364b2f6d7745633873425561.fake.io.
[INFO] Processing frame 00042b654c7255336270417039614e444a74364b2f6d7745633873425561
[INFO] Full resource record query was for: 00054a796250683772356832414f6b4a56657a7742424f4453563968464d.fake.io.
[INFO] Processing frame 00054a796250683772356832414f6b4a56657a7742424f4453563968464d
[INFO] Full resource record query was for: 000638773d3d.fake.io.
[INFO] Processing frame 000638773d3d
[INFO] Full resource record query was for: 00000000000000000000000000000000000000000000000000000000.fake.io.
[INFO] Processing frame 00000000000000000000000000000000000000000000000000000000
[OK] Message seems to be intact and passes sha1 checksum of 8bf2046ae2144be75d2ce780b3f992e2c368021e
[OK] Message was received in 8 requests
[INFO] Message has been decrypted with the configured secret
Message identifier: dns_message_test

---START OF MESSAGE---
This is a test message that will be sent over DNS
Cool eh?

---END OF MESSAGE---

Options

Sender (dns_send.py)

-S SERVER, --server=SERVER specify dns server to send requests to
-F FILE, --file=FILE specify the file to send
-I IDENT, --indentifier=IDENT specify a message indentifier
-X, --xxd Enable questions to be xxd -r friendly (60 charslong)
-s, --secret Set the secret used for the AES encryption
-d DOMAIN, --domain=DOMAIN fake zone to use for generated lookups

Receiver (dns_recv.py)

-L LISTEN, --listen=LISTEN specify hostname to listen on
-p PORT, --port=PORT port number to listen on (Defaults: 53)
-O OUT, --outfile=OUT specify a message file destination
-s, --secret Set the secret used for the AES encryption

Blog Entry Contact: @leonjza