Limitations of packet capture
You must be aware of certain limitations of packet capture.
Prerequisite
In the Library Manager, Application page, the Default Network Device field must be set to a physical interface.
Packet capture basics
Packet capture refers
to the interception of a data packet as it travels across a network.
Packet capture (as opposed to using an External Proxy Server)
is an option when setting the Recording mode for
the following transports:
- TCP
- FIX
- HTTP
Packet capture requires specialized software:
- On Windows™ systems, Network Packet Capture is included in the HCL OneTest™ API installation program. If necessary, you can rerun IBM® Installation Manager to add Network Packet Capture to the installation. See Installation of HCL OneTest API.
- On non-Windows systems, libpcap is typically installed by default. If necessary, you can download the latest package from http://www.tcpdump.org/.
If you choose Packet Capture as your Recording mode, HCL OneTest™ API calls the appropriate packet capture software automatically.
Limitations
Although packet capture is
simpler than using an external proxy server, be aware of the following
limitations:
- Your system administrator might not allow the use of packet capture software due to security concerns with intercepting traffic.
- On non-Windows systems, root permissions are required to access the network port in promiscuous mode, and thus to run packet capture.
- Packet capture does not work with wireless network adapters. Make sure that the Default Network Device in Library Manager is set to a physical interface.
- You can record only those messages that are sent from, or received by, the system running HCL OneTest™ API. You cannot record messages between remote systems.
- Packet capture cannot access messages that are sent locally on a Windows™ system, because these messages go through the internal loopback connector. For more information about the internal loopback connector, see http://wiki.wireshark.org/CaptureSetup/Loopback.