tools/process/pcap/pcapsync2008082322200808232009-02-12Tool to synchronize the timestamps of packets of 802.11-based experiments to a common time basis.

Pcapsync is a tool to time-synchronize tracefiles recorded in libpcap format. Its main application area are logfiles of real-world experiments with wireless multihop networks like MANETs (mobile ad-hoc networks), VANETs (vehicular ad-hoc networks) or mesh networks. The underlying algorithm, however, is more general and can be applied to any network with local broadcast characteristic.

v0.1tools/process/pcap/pcapsyncthe initial version.2008-08-23scheuerman-synchronizationREADMEhttp://www.crawdad.org/tools/process/pcap/pcapsynchttp://www.crawdad.org/wiki/pmwiki.php?n=Main.Tool.tools-process-pcap-pcapsync802.11MANETpacket tracetcpdumpvehicular networkwireless mesh networkwireless multihop networks204208209Before using the tool, we strongly recommend to read "On the Time Synchronization of Distributed Log Files in Networks with Local Broadcast Media", available at http://www.cn.uni-duesseldorf.de/publications/details/Scheuermann2008c.html This paper explains the details of the algorithm used for the synchronization, furthermore it contains some estimates of the achievable accuracy. To quote pcapsync, use this paper. For information, bug reports, feature requests, ... please refer to pcapsync@cs.uni-duesseldorf.deTo compile pcapsync, the following packages must be installed: - openssl for the lcrypto library - libpcap for the lpcap library - flex - bison Then type 'make'.- Input files naming convention The input files for pcapsync have to be named beginning with the MAC adress of the recording interface, followed by a dot. An example for this is "00099D9F1B3C.cap".Usage: pcapsync [flags] [options] <list_of_input_files> flags: -h Print this help text and terminate. -s Output one .synced file for each input file. -g Output a global .synced file to the output directory. -t Output files for use with tsc. -l Logs swaped packets during the synchronization. options: -o <outputDirectory> Defines an output directory. If no output directory is defined every output file is written to its input file directory.A fundamental problem in real-world computer network experiments is that each system uses its own local clock to timestamp events. These clocks are not perfectly accurate, and thus deviate from each other. Event timestamps assigned by different nodes can therefore not immediately be compared, making the analysis of experimental results difficult. In order to solve this issue we have proposed in a previous publication to record the occurring events with the deviating, local clocks and synchronize the resulting event log files offline after the experiment. The synchronization is based on so-called anchor points, that is, on events that have been recorded and timestamped by more than one node in parallel. The anchor points allow to set the clocks of the nodes into relation. In networks where the medium has a broadcast characteristic (like many wireless networks, but also Ethernet using hubs), the (almost) parallel reception of a packet transmission by multiple nodes can serve as such an anchor point. This algorithm is implemented in pcapsync, a tool to synchronize event logs from experiments in IEEE 802.11 wireless networks. It reads a set of log files that have been recorded in libpcap format (used, e. g., by tcpdump and Wireshark), identifies potential anchor points in them, applies our offline time synchronization algorithm, maps the recorded local timestamps to a common, global time scale, and finally writes back a corresponding set of synchronized libpcap files. Its output can thus immediately be used for further analysis with standard tools./download/tools/process/pcap/pcapsync/pcapsync_v0.1.tar.gz204tools/collect/multihop/EXCtools/process/pcap/pcapsyncWolfgang Kiesskiess@cs.uni-duesseldorf.deUniversität DüsseldorfInstitut für Informatik+49 211 81 11637+49 211 81 11638http://www.cn.uni-duesseldorf.de/staff/kiess208tools/process/pcap/pcapsyncBjörn Scheuermannscheuermann@cs.uni-duesseldorf.dethe Heinrich Heine UniversityComputer Networks and Communication SystemsJunior Professor+49 (211) 81 - 11692+49 (211) 81 - 11638http://www.cn.uni-duesseldorf.de/staff/scheuermann209tools/process/pcap/pcapsyncDaniel Marksthe Heinrich Heine UniversityComputer Networks and Communication Systems