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TCP Analyzer

TCP Congestion    Analyzer plugin for Unsniff

The TCP Analyzer is a free plugin that adds advanced TCP stream analysis capabilities to Unsniff Network Analyzer. The plugin installs as a new context menu item to each TCP stream. You can simply right click on a TCP Session and pull up various TCP charts.


  • Overview shows packets, retransmissions, out of order, duplicate acks in each direction
  • Sequence number chart, bandwidth, advertised window, inflight data
  • Congestion charts RTT (Round Trip Time) estimate, CWND, SSTHRESH estimate
  • Packet wise analysis
  • Export to PDF, XPS, print
  • Supports SACK

Sample chart (with dropdown showing available charts)

The following sample screenshot shows the Bandwidth characteristics of  the TCP connection in the direction of Clt > Svr (Client to Server where client is the machine that initiated the TCP connection).

TCP Analysis screenshot


How to install and use the plugin

To install the plugin :

  1. Download the plugin tcpana.dll from the Downloads page
  2. Right click and run Unsniff as Administrator
  3. Select Plugins > Install and select the tcpana.dll you downloaded
  4. Quit Unsniff and restart as normal user

To uninstall the plugin :

  1. Right click and run Unsniff as Administrator
  2. Select Plugins > Uninstall and select the tcpana.dll file
  3. Delete the tcpana.dll file

To use the plugin :

  1. The tcpana plugin adds a menu item to the sessions tab called "TCP Congestion Analyzer".
  2. Simply select a session, then right click and select the "TCP Congestion Analyzer" menu item.

Right click on a session and select the "TCP Congestion Analyzer" option.

Per packet TCP  analysis


Sequence Analysis

A very useful chart to detect TCP stalling is the sequence number analysis chart. The following screenshots show the sequence number chart in the two directions.


Forward Sequence chartReverse Sequence Chart


Per packet analysis

Each packet is marked with TCP analysis information such a retransmissions, out of orders, RTT estimates, SACK information, etc.

Per packet analysis



Other features

Click on the PDF icon to export to XPS

To export to PDF install CutePDF

Zoom In/Out

  1. Drag and select a time interval
  2. Press 'z' to zoom or 'x' to reset zoom
  3. Right click to access options
  4. Right click on the legend area to hide/show items


Export to PDF/XPS or Print