“UFTP is an encrypted multicast file transfer program, designed to securely, reliably, and efficiently transfer files to multiple receivers simultaneously. This is useful for distributing large files to a large number of receivers, and is especially useful for data distribution over a satellite link (with two way communication), where the inherent delay makes any TCP based communication highly inefficient. The multicast encryption scheme is based on TLS with extensions to allow multiple receivers to share a common key. UFTP also has the capability to communicate over disjoint networks separated by one or more firewalls (NAT traversal) and without full end-to-end multicast capability (multicast tunneling) through the use of a UFTP proxy server. These proxies also provide scalability by aggregating responses from a group of receivers.
UFTP has been used in the production process of The Wall Street Journal
to send WSJ pages over satellite to their remote printing plants, and
other users have used it to send to over 1000 receivers.
h3. Protocol Summary
A UFTP session consists of 3 main phases: The Announce/Register phase, the File Transfer phase, and the Completion/Confirmation phase. The File Transfer phase additionally consists of the File Info phase and the Data Transfer phase for each file sent.
The Announce/Register phase sets up the multicast file transfer session and negotiates all encryption parameters. The server sends out an announcement over a public multicast address which the clients are expected to be listening on. All subsequent messages from the server go over a private multicast address specified in the announcement. Allowed clients send a registration to respond to the announcement. The server will then send either a confirmation message if encryption is disabled, or the encryption key for the session if encryption is enabled. If the client receives the encryption key, it sends an acknowledgment back to the server.
The File Transfer phase starts with the File Info phase for the first file to send. The server sends a message describing the file in question. Besides the name and size of the file, this message describes how the file will be broken down. A file is divided into a number of blocks, and these blocks are grouped into sections. A block is a piece of the file that is sent in a single packet. A section is a grouping of blocks that can be sent together before the server needs to request feedback from the clients. The total number of blocks and sections is included in this message.
Continuing the File Transfer phase is the Data Transfer phase for the first file. Data packets, each of which is a block, are sent by the server at a rate specified by the user. Because UDP does not guarantee that packets will arrive in order, each block is numbered so the client can properly reassemble the file. When the server finishes a section, it send a message to the clients requesting status. The clients then send back a status message containing the list of NAKs (negative acknowledgments) for the blocks in that section. Once all sections have been sent, if the server has received a non zero number of NAKs from any client, the server will begin a second pass of the data, this time only sending the packets that were NAKed. The server will continue with subsequent passes of the data until all clients have either received the file or have timed out while the server was waited for a status message. When a client has received the entire file, it sends a completion message in response to the next status request.
The File Info phase and the Data Transfer phase are then repeated for each file to be sent during the session
The Completion/Confirmation phase shuts down the session between the server and clients. It starts with a message from the server indicating the end of the session. The clients then respond with a completion message, and the server responds to each completion with a confirmation message.”http://www.tcnj.edu/~bush/uftp.html
Before running UFTP you have to make user that the routing table on your
machine has has a static multi-cast route enabled.
On Linux: route add -net 126.96.36.199. netmask 240.0.0.0 dev iface
Run tests by exchanging files between a client (uftpd) and a server (uftp).
UFTP Server command example:
uftp -Y aes256 -h sha1 FILE = server sends FILE over tls encrypted with aes256 and sha1
UFTP Client command example:
uftpd -D RECV-DIR -T TEMP-DIR -L LOG= client daemon saves files received RECV-DIR and temporary files (in case communication is interrupted) to TEMP-DIR and logs to LOG
Router > Router: In this setting we have the uftp package installed on two adjacent routers. One servers as a client, the other as the server…. IT WORKS!
Host > Router: The host is directly connected to the router
matt@wontseeme:~/src/bismark_week/uftp-3.5.1$ ./uftp -D -R 500 /home/matt/Dropbox/ebooks/R/02_corpus_frequency_data.slides.pdf UFTP version 3.5.1 Copyright (C) 2001-2011 Dennis A. Bush Starting at Thu Jul 14 12:37:08 2011 Transfer rate: 1000 Kbps (125 KB/s) Wait between packets: 11718 us Using private multicast address 188.8.131.52 Group ID: 549A4C1C Initializing group Sending ANNOUNCE 1 Sending ANNOUNCE 2 Received REGISTER from client gw.jc.lab.projectbismark.net Sending REG_CONF 3.1 Sending ANNOUNCE 3 Received REGISTER from client gw.jc.lab.projectbismark.net Sending REG_CONF 4.1 Sending ANNOUNCE 4 ----- 500 ----- Error getting file status for 500: No such file or directory ----- 02_corpus_frequency_data.slides.pdf ----- File ID: 0001 Name: 02_corpus_frequency_data.slides.pdf sending as R/02_corpus_frequency_data.slides.pdf Bytes: 6071756 Blocks: 4205 Sections: 1 Sending FILEINFO 1.1 Received INFO_ACK from client gw.jc.lab.projectbismark.net Sending FILEINFO 2.1 Received INFO_ACK+ from client gw.jc.lab.projectbismark.net Sending FILEINFO 3.1 Received INFO_ACK+ from client gw.jc.lab.projectbismark.net Sending FILEINFO 4.1 Received INFO_ACK+ from client gw.jc.lab.projectbismark.net Couldn't get INFO_ACK from gw.jc.lab.projectbismark.net Maximum file transfer time: 142 seconds Sending file...pass 1 Sending DONE 1.1 Got 20 NAKs for pass 1 section 1 from client gw.jc.lab.projectbismark.net Average wait time = 11718.04 us Received 20 distinct NAKs for pass 1 Sending file...pass 2 Sending DONE 1.1 Got COMPLETE from client gw.jc.lab.projectbismark.net Average wait time = 11727.70 us Received 0 distinct NAKs for pass 2 Transfer status: Host: gw.jc.lab.projectbismark.net Status: Completed time: 52.364 seconds NAKs: 20 Host: gw.jc.lab.projectbismark.net Status: Lost connection Total elapsed time: 52.364 seconds Overall throughput: 113.24 KB/s ----------------------------- Finishing group Sending DONE 1.1 Got COMPLETE from client gw.jc.lab.projectbismark.net Late completions: Sending DONE_CONF 2.1 Group complete uftp: Finishing at Thu Jul 14 12:38:28 2011
uftpd -D /tmp/recv_dir
Host > Host
Router > Multiple Hosts: DOES NOT WORK!
/uftpd -D /home/matt/src/bismark_week/ -L works ; tail -f works
2011/07/14 11:30:28.195551: UFTP version 3.5.1 Copyright © 2001-2011
Dennis A. Bush
2011/07/14 11:30:28.196667: Loaded key with fingerprint 12:7F:6E:58:60:85:63:E4:64:71:25:FA:80:FC:53:F6:46:87:2E:B9
root@gw:~# uftp -D -L /tmp/1stlog /tmp/file.test
root@gw:~# du /tmp/file.test
Note: the 1stlog file is never created.
Routers: Netgear WNDR3700V2 Running CeroWRT smoketest
Host A: Thinkpad X61s
Linux wontseeme 2.6.38-7.dmz.1-liquorix-amd64 #1 ZEN SMP PREEMPT Sun May 22 23:53:16 CDT 2011 x86_64 x86_64 x86_64 GNU/Linux
Host B: Virtualized instance of Ubuntu 10.10 on Macbook Pro
Macbook: Processor 2 Ghz Intel Core 2 Duo, Memory 2 GB 1067 MHz DDR3 running Mac OS X version 10.6.8
VM: Linux jupiter 2.6.35-30-generic #54-Ubuntu SMP Tue Jun 7 18:40:23 UTC 2011 i686 GNU/Linux