tcpconnect.bt

#!/usr/bin/env bpftrace
/*
 * tcpconnect.bt  Trace TCP connect()s.
 *                For Linux, uses bpftrace and eBPF.
 *
 * USAGE: tcpconnect.bt
 *
 * This is a bpftrace version of the bcc tool of the same name.
 * It is limited to ipv4 addresses.
 *
 * All connection attempts are traced, even if they ultimately fail.
 *
 * This uses dynamic tracing of kernel functions, and will need to be updated
 * to match kernel changes.
 *
 * Copyright (c) 2018 Dale Hamel.
 * Licensed under the Apache License, Version 2.0 (the "License")
 *
 * 23-Nov-2018	Dale Hamel	created this.
 */

#ifndef BPFTRACE_HAVE_BTF
#include <linux/socket.h>
#include <net/sock.h>
#else
#include <sys/socket.h>
#endif

BEGIN
{
  printf("Tracing tcp connections. Hit Ctrl-C to end.\n");
  printf("%-8s %-8s %-16s ", "TIME", "PID", "COMM");
  printf("%-39s %-6s %-39s %-6s\n", "SADDR", "SPORT", "DADDR", "DPORT");
}

kprobe:tcp_connect
{
  $sk = ((struct sock *) arg0);
  $inet_family = $sk->__sk_common.skc_family;

  if ($inet_family == AF_INET || $inet_family == AF_INET6) {
    if ($inet_family == AF_INET) {
      $daddr = ntop($sk->__sk_common.skc_daddr);
      $saddr = ntop($sk->__sk_common.skc_rcv_saddr);
    } else {
      $daddr = ntop($sk->__sk_common.skc_v6_daddr.in6_u.u6_addr8);
      $saddr = ntop($sk->__sk_common.skc_v6_rcv_saddr.in6_u.u6_addr8);
    }
    $lport = $sk->__sk_common.skc_num;
    $dport = $sk->__sk_common.skc_dport;

    // Destination port is big endian, it must be flipped
    $dport = bswap($dport);

    time("%H:%M:%S ");
    printf("%-8d %-16s ", pid, comm);
    printf("%-39s %-6d %-39s %-6d\n", $saddr, $lport, $daddr, $dport);
  }
}