* Question about udp.sendmsg / udp.recvmsg
@ 2020-07-16 4:01 Lee Eric
0 siblings, 0 replies; only message in thread
From: Lee Eric @ 2020-07-16 4:01 UTC (permalink / raw)
To: systemtap
Hi,
I have a quick question about what udp.sendmsg captures. I wrote a
small script to capture all processes are sending / receiving UDP
packets:
#!/usr/bin/env stap
probe udp.sendmsg {
printf("Req - time: [%s] pid: [%d] cmd: [%s] %s:%d => %s:%d\n",
ctime(gettimeofday_s()), pid(), execname(), saddr, sport, daddr,
dport)
}
probe udp.recvmsg {
printf("Resp - time: [%s] pid: [%d] cmd: [%s] %s:%d => %s:%d\n",
ctime(gettimeofday_s()), pid(), execname(), daddr, dport, saddr,
sport)
}
So I also triggered tcpdump to capture UDP traffic. I noticed the
systemtap shows some udp.sendmsg / udp.recvmsg probes are triggered
but there's no request on tcpdump side. So what possible reason can
cause this behavior? Is that normal?
Thanks.
Eric
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