captest - Linux


captest is a command-line tool for capturing and analyzing network traffic. It can be used for troubleshooting network connectivity issues, monitoring traffic patterns, and identifying potential security threats.


captest [options] [interface] [filter]


  • -c, –count: Capture X packets and exit.
  • -i, –interface: Network interface to capture traffic from.
  • -f, –filter: BPF filter to apply to captured traffic.
  • -t, –timeout: Number of seconds to capture traffic for. Default: 10
  • -s, –snaplen: Maximum size of packets to capture. Default: 65535
  • -w, –write: File to write captured packets to.
  • -r, –read: File to read captured packets from.
  • -h, –help: Display help and usage information.


Simple capture:


Capture on specific interface:

captest -i eth0

Apply BPF filter:

captest -f "host"

Limit packets count:

captest -c 100

Capture to file:

captest -w my_capture.pcap

Read packets from file:

captest -r my_capture.pcap

Common Issues

  • No traffic captured: Ensure the specified network interface is up and running.
  • Invalid BPF filter: Check the syntax of your filter expression.
  • Large capture file: Monitor traffic for only as long as necessary and use filters to reduce captured data.


Analyze with Wireshark:

captest -w capture.pcap && wireshark -r capture.pcap

Extract traffic statistics:

captest -c 1000 | tcpdump -nn -c 1000 | cut -d " " -f 8,11,13,14 | sort -k 2

Related Commands

  • tcpdump
  • Wireshark
  • netstat