#!/usr/bin/python
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#
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# tcpv4connect Trace TCP IPv4 connect()s.
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# For Linux, uses BCC, eBPF. Embedded C.
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#
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# USAGE: tcpv4connect [-h] [-t] [-p PID]
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#
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# This is provided as a basic example of TCP connection & socket tracing.
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#
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# All IPv4 connection attempts are traced, even if they ultimately fail.
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#
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# Copyright (c) 2015 Brendan Gregg.
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# Licensed under the Apache License, Version 2.0 (the "License")
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#
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# 15-Oct-2015 Brendan Gregg Created this.
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from __future__ import print_function
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from bcc import BPF
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# define BPF program
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bpf_text = """
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#include <uapi/linux/ptrace.h>
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#include <net/sock.h>
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#include <bcc/proto.h>
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BPF_HASH(currsock, u32, struct sock *);
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int kprobe__tcp_v4_connect(struct pt_regs *ctx, struct sock *sk)
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{
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u32 pid = bpf_get_current_pid_tgid();
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// stash the sock ptr for lookup on return
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currsock.update(&pid, &sk);
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return 0;
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};
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int kretprobe__tcp_v4_connect(struct pt_regs *ctx)
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{
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int ret = PT_REGS_RC(ctx);
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u32 pid = bpf_get_current_pid_tgid();
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struct sock **skpp;
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skpp = currsock.lookup(&pid);
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if (skpp == 0) {
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return 0; // missed entry
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}
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if (ret != 0) {
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// failed to send SYNC packet, may not have populated
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// socket __sk_common.{skc_rcv_saddr, ...}
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currsock.delete(&pid);
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return 0;
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}
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// pull in details
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struct sock *skp = *skpp;
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u32 saddr = skp->__sk_common.skc_rcv_saddr;
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u32 daddr = skp->__sk_common.skc_daddr;
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u16 dport = skp->__sk_common.skc_dport;
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// output
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bpf_trace_printk("trace_tcp4connect %x %x %d\\n", saddr, daddr, ntohs(dport));
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currsock.delete(&pid);
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return 0;
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}
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"""
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# initialize BPF
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b = BPF(text=bpf_text)
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# header
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print("%-6s %-12s %-16s %-16s %-4s" % ("PID", "COMM", "SADDR", "DADDR",
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"DPORT"))
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def inet_ntoa(addr):
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dq = ''
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for i in range(0, 4):
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dq = dq + str(addr & 0xff)
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if (i != 3):
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dq = dq + '.'
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addr = addr >> 8
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return dq
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# filter and format output
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while 1:
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# Read messages from kernel pipe
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try:
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(task, pid, cpu, flags, ts, msg) = b.trace_fields()
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(_tag, saddr_hs, daddr_hs, dport_s) = msg.split(" ")
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except ValueError:
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# Ignore messages from other tracers
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continue
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# Ignore messages from other tracers
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if _tag != "trace_tcp4connect":
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continue
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print("%-6d %-12.12s %-16s %-16s %-4s" % (pid, task,
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inet_ntoa(int(saddr_hs, 16)),
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inet_ntoa(int(daddr_hs, 16)),
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dport_s))
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