CrackerCat / ptcpdump

Process-aware, eBPF-based tcpdump

ptcpdump

ptcpdump is the tcpdump(8) implementation using eBPF, with an extra feature: it adds process info as packet comments for each Packet when possible.

Table of Contents

• Features
• Installation
  • Requirements
• Usage
  • Example output
• Compare with tcpdump

Features

• Aware of the process information associated with the packets.
• Supports using pcap-filter(7) syntax for filtering packets.
• Supports filtering packets by process ID and process name.
• Directly applies filters in the kernel space.
• Supports saving captured packets in the PcapNG format for offline analysis with third-party tools such as Wireshark.
• Supports reading packets from pcapng file.

Installation

Please download the latest binary in the releases.

Requirements

Linux kernel version >= 5.2.

Usage

Usage:
  ptcpdump [flags] [expression]

Examples:
  ptcpdump -i any tcp

  ptcpdump -i eth0 --pid 1234 port 80 and host 10.10.1.1

  ptcpdump -i any --pname curl

  ptcpdump -i any -w ptcpdump.pcapng

  ptcpdump -r ptcpdump.pcapng

Expression: see "man 7 pcap-filter"

Flags:
  -Q, --direction string     Choose send/receive direction for which packets should be captured. Possible values are 'in', 'out' and 'inout' (default "inout")
  -f, --follow-forks         Trace child processes as they are created by currently traced processes when filter by process
  -h, --help                 help for ptcpdump
  -i, --interface strings    Interfaces to capture (default [lo])
      --list-interfaces      Print the list of the network interfaces available on the system
      --pid uint             Filter by process ID (only TCP and UDP packets are supported)
      --pname string         Filter by process name (only TCP and UDP packets are supported)
      --print                Print parsed packet output, even if the raw packets are being saved to a file with the -w flag
  -r, --read-file string     Read packets from file (which was created with the -w option). e.g. ptcpdump.pcapng
  -c, --receive-count uint   Exit after receiving count packets
      --version              Print the ptcpdump and libpcap version strings and exit
  -w, --write-file string    Write the raw packets to file rather than parsing and printing them out. They can later be printed with the -r option. e.g. ptcpdump.pcapng

Example output

18:05:35.441022 wlp4s0 In IP (tos 0x4, ttl 51, id 0, offset 0, flags [DF], ip_proto TCP (6), length 60)
    185.125.190.29.80 > 192.168.1.50.41966: Flags [S.], cksum 0x68fd, seq 3647722906, ack 1664327469, win 65160, options [mss 1452,sackOK,TS val 1103153989 ecr 3934018003,nop,wscale 7], length 0
    Process (pid 892817, cmd /usr/bin/curl, args curl ubuntu.com)
18:05:35.441298 wlp4s0 Out IP (tos 0x0, ttl 64, id 19415, offset 0, flags [DF], ip_proto TCP (6), length 126)
    192.168.1.50.41966 > 185.125.190.29.80: Flags [P.], cksum 0x39e6, seq 1664327469:1664327543, ack 3647722907, win 502, options [nop,nop,TS val 3934018248 ecr 1103153989], length 74
    Process (pid 892817, cmd /usr/bin/curl, args curl ubuntu.com)

Compare with tcpdump

Options	tcpdump	ptcpdump
expression	✅	✅
-i interface, --interface=interface	✅	✅
-w x.pcapng	✅	✅ (with process info)
-w x.pcap	✅	✅ (without process info)
-w -	✅
-r x.pcapng, -r x.pcap	✅	✅
-r -	✅
--pid process_id		✅
--pname process_name		✅
-f, --follow-forks		✅
--print	✅	✅
-c count	✅	✅
-Q direction, --direction=direction	✅	✅
--list-interfaces	✅	✅
-A	✅
-B bufer_size, --buffer-size=buffer_size	✅
--count	✅
-C *file_size	✅
-d	✅
-dd	✅
-ddd	✅
-D	✅
-e	✅
-f	✅	⛔
-F file	✅
-G rotate_seconds	✅
-h	✅	✅
--help	✅	✅
--version	✅	✅
-H	✅
-l, --monitor-mode	✅
--immediate-mode	✅
-j tstamp_type, --time-stamp-type=tstamp_type	✅
-J, --list-time-stamp-types	✅
--time-stamp-precision=tstamp_precision	✅
--micro	✅
--nano	✅
-K, --dont-verify-checksums	✅
-l	✅
-L, --list-data-link-types	✅
-m module	✅
-M secret	✅
-n	✅
-N	✅
-#	✅	⛔
--number	✅
-O, --no-optimize	✅
-p, --no-promiscuous-mode	✅	⛔
-S, --absolute-tcp-sequence-numbers	✅
-s snaplen, --snapshot-length=snaplen	✅
-T type	✅
-t	✅
-tt	✅
-ttt	✅
-tttt	✅
-u	✅
-U, --packet-buffered	✅
-v	✅
-vv	✅
-vvv	✅
-V file	✅
-W filecont	✅
-x	✅
-xx	✅
-X	✅
-XX	✅
-y datalinktype, --linktype=datalinktype	✅
-z postrotate-command	✅
-Z user, --relinquish-privileges=user	✅