bpftrace - tcpstates.bt

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#bpftrace #bcc #bpf #tcpstates

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bpftrace-tcpstates.bt是一个基于BCC工具集的脚本，用于跟踪和显示系统的TCP连接状态变化。它通过在内核态的tcp_set_state函数上设置探针来监控TCP状态机。脚本输出包括本地和远程地址、端口以及连接状态的转换，如SYN_SENT、ESTABLISHED、CLOSED等，帮助用户理解TCP连接的生命周期。

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bpftrace - tcpstates.bt

此工具参考bcc-tcpstates编写, 用于实现跟踪系统 TCP 连接状态(TCP状态机)。
通过在内核态动态函数 kprobe:tcp_set_state 插桩监控 sock 状态变化实现:

#!/usr/bin/env bpftrace
#include <net/tcp_states.h>
#include <net/sock.h>
#include <linux/socket.h>
#include <linux/tcp.h>

BEGIN
{
	printf("%-20s %-7s %-20s %-7s ",
	    "LADDR", "LPORT", "RADDR", "RPORT");
	printf("%-11s -> %-11s\n", "OLD", "NEW");
	@tcpstate[0] = "UNKNOWN";
	@tcpstate[1] = "ESTABLISHED";
	@tcpstate[2] = "SYN_SENT";
	@tcpstate[3] = "SYN_RECV";
	@tcpstate[4] = "FIN_WAIT1";
	@tcpstate[5] = "FIN_WAIT2";
	@tcpstate[6] = "TIME_WAIT";
	@tcpstate[7] = "CLOSE";
	@tcpstate[8] = "CLOSE_WAIT";
	@tcpstate[9] = "LAST_ACK";
	@tcpstate[10] = "LISTEN";
	@tcpstate[11] = "CLOSING";
	@tcpstate[12] = "NEW_SYN_RECV";
}

kprobe:tcp_set_state
{
	$sk = (struct sock *)arg0;
	$newstate = arg1;
	$oldstate = $sk->__sk_common.skc_state;

	$lport = $sk->__sk_common.skc_num;
	$dport = $sk->__sk_common.skc_dport;
	$dport = ($dport >> 8) | (($dport << 8) & 0xff00);

	$family = $sk->__sk_common.skc_family;
	$saddr = ntop(0);
	$daddr = ntop(0);
	if ($family == AF_INET) {
		$saddr = ntop(AF_INET, $sk->__sk_common.skc_rcv_saddr);
		$daddr = ntop(AF_INET, $sk->__sk_common.skc_daddr);
	} else {
		// AF_INET6
		$saddr = ntop(AF_INET6,
			$sk->__sk_common.skc_v6_rcv_saddr.in6_u.u6_addr8);
		$daddr = ntop(AF_INET6,
			$sk->__sk_common.skc_v6_daddr.in6_u.u6_addr8);
	}
	if ($newstate > 12) {
		printf("%-20s %-7d %-20s %-7d %-11d -> %-11d\n", $saddr, $lport, $daddr, $dport, $oldstate, $newstate);
	} else {
		printf("%-20s %-7d %-20s %-7d %-11s -> %-11s\n", $saddr, $lport, $daddr, $dport, @tcpstate[$oldstate], @tcpstate[$newstate]);
	}
}

END
{
	clear(@tcpstate)
}

运行结果:

# ./tcpstates.bt 
Attaching 3 probes...
LADDR                LPORT   RADDR                RPORT   OLD         -> NEW        
192.168.22.42        0       192.168.22.44      3310    CLOSE       -> SYN_SENT   
192.168.22.42        37626   192.168.22.44      3310    SYN_SENT    -> ESTABLISHED
192.168.22.42        37626   192.168.22.44      3310    ESTABLISHED -> FIN_WAIT1  
192.168.22.42        37626   192.168.22.44      3310    FIN_WAIT1   -> FIN_WAIT2  
192.168.22.42        37626   192.168.22.44      3310    FIN_WAIT2   -> CLOSE      
192.168.22.42        0       192.168.22.44      3310    CLOSE       -> SYN_SENT   
192.168.22.42        37628   192.168.22.44      3310    SYN_SENT    -> ESTABLISHED
192.168.22.42        37628   192.168.22.44      3310    ESTABLISHED -> CLOSE      
192.168.22.42        0       192.168.22.44      3310    CLOSE       -> SYN_SENT   
192.168.22.42        37630   192.168.22.44      3310    SYN_SENT    -> ESTABLISHED
192.168.22.42        37630   192.168.22.44      3310    ESTABLISHED -> CLOSE_WAIT 
192.168.22.42        37630   192.168.22.44      3310    CLOSE_WAIT  -> LAST_ACK   
192.168.22.42        37630   192.168.22.44      3310    LAST_ACK    -> CLOSE      
192.168.22.42        0       192.168.22.44      3310    CLOSE       -> SYN_SENT   
192.168.22.42        37634   192.168.22.44      3310    SYN_SENT    -> CLOSE