Try this configuration.

To dump network traffic, use the tcpdump EXEC command.

tcpdump [LINE]

TCPdump is a utility that allows a user to intercept and capture packets passing through a network interface, making it useful for troubleshooting network applications.

To analyze network traffic from the command line, use the tethereal EXEC command.

tethereal [LINE]

Tethereal is the command-line version of the network traffic analyzer tool Ethereal. Like TCPdump, it also uses the packet capture library (libpcap). Aside from network traffic analysis, Tethereal also provides facilities for decoding packets.