From a7a39f89b58da3eb939f7233c23f8eb225826d48 Mon Sep 17 00:00:00 2001 From: Phil Sutter Date: Wed, 30 Mar 2016 16:51:09 +0200 Subject: [PATCH] man: tc-mirred.8: Reword man page a bit, add generic mirror example Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1275426 Upstream Status: iproute2.git commit 26df2953a5c34 commit 26df2953a5c34fe03986cbf3466321fd8a3af1c5 Author: Phil Sutter Date: Tue Mar 22 15:48:35 2016 +0100 man: tc-mirred.8: Reword man page a bit, add generic mirror example Signed-off-by: Phil Sutter Signed-off-by: Stephen Hemminger --- man/man8/tc-mirred.8 | 26 +++++++++++++++++++------- 1 file changed, 19 insertions(+), 7 deletions(-) diff --git a/man/man8/tc-mirred.8 b/man/man8/tc-mirred.8 index 52d98bc..bba96e0 100644 --- a/man/man8/tc-mirred.8 +++ b/man/man8/tc-mirred.8 @@ -21,11 +21,9 @@ mirred - mirror/redirect action .SH DESCRIPTION The .B mirred -action allows to redirect or mirror packets to another network interface on the -same system. It is typically used in combination with the -.B ifb -pseudo device to create a shrared instance where QoS happens, but serves well -for debugging or monitoring purposes, too. +action allows packet mirroring (copying) or redirecting (stealing) the packet it +receives. Mirroring is what is sometimes referred to as Switch Port Analyzer +(SPAN) and is commonly used to analyze and/or debug flows. .SH OPTIONS .TP .B ingress @@ -67,9 +65,23 @@ debugging purposes: .EE .RE -Use an +Mirror all incoming ICMP packets on eth0 to a dummy interface for examination +with e.g. tcpdump: + +.RS +.EX +# ip link add dummy0 type dummy +# ip link set dummy0 up +# tc qdisc add dev eth0 handle ffff: ingress +# tc filter add dev eth0 parent ffff: protocol ip \\ + u32 match ip protocol 1 0xff \\ + action mirred egress mirror dev dummy0 +.EE +.RE + +Using an .B ifb -interface to send ingress traffic on eth0 through an instance of +interface, it is possible to send ingress traffic through an instance of .BR sfq : .RS -- 1.8.3.1