You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
74 lines
1.8 KiB
74 lines
1.8 KiB
.TH tcpdrop 8 "2018-05-30" "USER COMMANDS"
|
|
.SH NAME
|
|
tcpdrop \- Trace kernel-based TCP packet drops with details. Uses Linux eBPF/bcc.
|
|
.SH SYNOPSIS
|
|
.B tcpdrop [\-h] [\-T] [\-t] [\-w] [\-s] [\-p PID] [\-D PORTS] [\-L PORTS]
|
|
.SH DESCRIPTION
|
|
This tool traces TCP packets or segments that were dropped by the kernel, and
|
|
shows details from the IP and TCP headers, the socket state, and the
|
|
kernel stack trace. This is useful for debugging cases of high kernel drops,
|
|
which can cause timer-based retransmits and performance issues.
|
|
|
|
This tool works using dynamic tracing of the tcp_drop() kernel function,
|
|
which requires a recent kernel version.
|
|
|
|
Since this uses BPF, only the root user can use this tool.
|
|
.SH REQUIREMENTS
|
|
CONFIG_BPF and bcc.
|
|
.SH OPTIONS
|
|
.TP
|
|
\-h
|
|
Print usage message.
|
|
.B tcpdrop
|
|
.SH FIELDS
|
|
.TP
|
|
TIME
|
|
Time of the drop, in HH:MM:SS format.
|
|
.TP
|
|
PID
|
|
Process ID that was on-CPU during the drop. This may be unrelated, as drops
|
|
can occur on the receive interrupt and be unrelated to the PID that was
|
|
interrupted.
|
|
.TP
|
|
IP
|
|
IP address family (4 or 6)
|
|
.TP
|
|
SADDR
|
|
Source IP address.
|
|
.TP
|
|
SPORT
|
|
Source TCP port.
|
|
.TP
|
|
DADDR
|
|
Destination IP address.
|
|
.TP
|
|
DPORT
|
|
Destionation TCP port.
|
|
.TP
|
|
STATE
|
|
TCP session state ("ESTABLISHED", etc).
|
|
.TP
|
|
FLAGS
|
|
TCP flags ("SYN", etc).
|
|
.SH OVERHEAD
|
|
This traces the kernel tcp_drop() function, which should be low frequency,
|
|
and therefore the overhead of this tool should be negligible.
|
|
|
|
As always, test and understand this tools overhead for your types of
|
|
workloads before production use.
|
|
.SH SOURCE
|
|
This is from bcc.
|
|
.IP
|
|
https://github.com/iovisor/bcc
|
|
.PP
|
|
Also look in the bcc distribution for a companion _examples.txt file containing
|
|
example usage, output, and commentary for this tool.
|
|
.SH OS
|
|
Linux
|
|
.SH STABILITY
|
|
Unstable - in development.
|
|
.SH AUTHOR
|
|
Brendan Gregg
|
|
.SH SEE ALSO
|
|
tcplife(8), tcpaccept(8), tcpconnect(8), tcptop(8)
|