D-Link DWL-3600AP Administrator's Manual page 126

Unified Access Point Administrator's Guide
To configure Wireshark to use the AP as the source for captured packets, you must specify the remote interface
in the "Capture Options" menu. For example to capture packets on an AP with IP address 192.168.1.10 on radio
1 using the default IP port, specify the following interface:
rpcap://192.168.1.10/radio1
To capture packets on the Ethernet interface of the AP and VAP0 on radio 1 using IP port 58000, start two
Wireshark sessions and specify the following interfaces:
rpcap://192.168.1.10:58000/eth0
rpcap://192.168.1.10:58000/wlan0
When you are capturing traffic on the radio interface, you can disable beacon capture, but other 802.11 control
frames are still sent to Wireshark. You can set up a display filter to show only:
• Data frames in the trace
• Traffic on specific BSSIDs
• Traffic between two clients
Some examples of useful display filters are:
• Exclude beacons and ACK/RTS/CTS frames:
!(wlan.fc.type_subtype == 8 || wlan.fc.type == 1)
• Data frames only:
wlan.fc.type == 2
• Traffic on a specific BSSID:
wlan.bssid == 00:02:bc:00:17:d0
• All traffic to and from a specific client:
wlan.addr == 00:00:e8:4e:5f:8e
In remote capture mode, traffic is sent to the PC running Wireshark via one of the network interfaces.
Depending on where the Wireshark tool is located the traffic can be sent on an Ethernet interface or one of the
radios. In order to avoid a traffic flood caused by tracing the trace packets, the AP automatically installs a
capture filter to filter out all packets destined to the Wireshark application. For example if the Wireshark IP port
is configured to be 58000 then the following capture filter is automatically installed on the AP:
not portrange 58000‐58004.
Enabling the packet capture feature impacts performance of the AP and can create a security issue
(unauthorized clients may be able to connect to the AP and trace user data). The AP performance is negatively
impacted even if there is no active Wireshark session with the AP. The performance is negatively impacted to
a greater extent when packet capture is in progress.
Due to performance and security issues, the packet capture mode is not saved in NVRAM on the AP; if the AP
resets, the capture mode is disabled and the you must re‐enable it in order to resume capturing traffic. Packet
capture parameters (other than mode) are saved in NVRAM.
D-Link
November 2011
Packet Capture Configuration and Settings
Unified Access Point Administrator's Guide
Page 126