TIME protocol extension

This Scapy add-on provides some layers for the TIME protocol over UDP as specified in RFC 868.

The TIME protocol is much simpler than NTP and less accurate. This is more of an educational example. Have a look at the code.

Usage

Run the attached time-rfc-868-ext.py script and you'll get an interactive prompt: 

Welcome to Scapy (1.2.0.2)
TIME protocol (RFC 868) extension v0.2
>>>

First we ask the server time-a.nist.gov for the current time: 

>>> a,u=sr(IP(dst="time-a.nist.gov")/UDP()/TIME_Req())
Begin emission:
Finished to send 1 packets.
...*
Received 4 packets, got 1 answers, remaining 0 packets
>>> a.summary()
IP / UDP 192.168.1.10:3737 > 129.6.15.28:time / TIME_Req ==> IP / UDP 129.6.15.2
8:time > 192.168.1.10:3737 / TIME_Resp / Padding
>>> a[0][1]
<IP  version=4L ihl=5L tos=0x0 len=32 id=7384 flags= frag=0L ttl=53 proto=udp 
chksum=0x1721 src=129.6.15.28 dst=192.168.1.10 options='' |
<UDP  sport=time dport=3737 len=12 chksum=0x1873 |
<TIME_Resp  time_stamp='Sat Apr 05 10:47:42 2008' |
<Padding  load='\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00' |>>>>

The results are show in the time_stamp attribute of the response.

We can run our own time server as well. It will listen for requests and return the current system time in response: 

>>> TIME_server()
Ether / IP / UDP 192.168.1.11:1053 > 192.168.1.10:time / Padding ==> IP / UDP 19
2.168.1.10:time > 192.168.1.11:1053 / Raw

Known bugs

TIME requests technically do not have to have a payload. Currently, those packets are dissected only as UDP datagrams and not as TIME requests.

See also

Credits

The TIME protocol extension was written by Dirk Loss (2008-04-05) and is licensed under the GNU GPL.

Attachments