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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXAMPLES | LIMITATIONS | SEE ALSO | COLOPHON |
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Mirror/redirect action in tc(8) Linux Mirror/redirect action in tc(8)
mirred - mirror/redirect action
tc ... action mirred DIRECTION ACTION [ index INDEX ] TARGET
DIRECTION := { ingress | egress }
TARGET := { DEV | BLOCK }
DEV := dev DEVICENAME
BLOCK := blockid BLOCKID
ACTION := { mirror | redirect }
The mirred 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. When mirroring to a tc block, the
packet will be mirrored to all the ports in the block with
exception of the port where the packet ingressed, if that port is
part of the tc block. Redirecting is similar to mirroring except
that the behaviour is to mirror to the first N - 1 ports in the
block and redirect to the last one (note that the port in which
the packet arrived is not going to be mirrored or redirected to).
ingress
egress Specify the direction in which the packet shall appear on
the destination interface.
mirror
redirect
Define whether the packet should be copied (mirror) or
moved (redirect) to the destination interface or block.
index INDEX
Assign a unique ID to this action instead of letting the
kernel choose one automatically. INDEX is a 32bit unsigned
integer greater than zero.
dev DEVICENAME
Specify the network interface to redirect or mirror to.
blockid BLOCKID
Specify the tc block to redirect or mirror to.
Limit ingress bandwidth on eth0 to 1mbit/s, redirect exceeding
traffic to lo for debugging purposes:
# tc qdisc add dev eth0 handle ffff: clsact
# tc filter add dev eth0 ingress u32 \
match u32 0 0 \
action police rate 1mbit burst 100k conform-exceed pipe \
action mirred egress redirect dev lo
Mirror all incoming ICMP packets on eth0 to a dummy interface for
examination with e.g. tcpdump:
# ip link add dummy0 type dummy
# ip link set dummy0 up
# tc qdisc add dev eth0 handle ffff: clsact
# tc filter add dev eth0 ingress protocol ip \
u32 match ip protocol 1 0xff \
action mirred egress mirror dev dummy0
Using an ifb interface, it is possible to send ingress traffic
through an instance of sfq:
# modprobe ifb
# ip link set ifb0 up
# tc qdisc add dev ifb0 root sfq
# tc qdisc add dev eth0 handle ffff: clsact
# tc filter add dev eth0 ingress u32 \
match u32 0 0 \
action mirred egress redirect dev ifb0
The kernel restricts nesting to four levels to avoid the chance of
nesting loops.
Do not redirect for one IFB device to another. IFB is a very
specialized case of packet redirecting device. Redirecting from
ifbX->ifbY will cause all packets to be dropped.
tc(8), tc-u32(8)
This page is part of the iproute2 (utilities for controlling
TCP/IP networking and traffic) project. Information about the
project can be found at
⟨http://www.linuxfoundation.org/collaborate/workgroups/networking/iproute2⟩.
If you have a bug report for this manual page, send it to
netdev@vger.kernel.org, shemminger@osdl.org. This page was
obtained from the project's upstream Git repository
⟨https://git.kernel.org/pub/scm/network/iproute2/iproute2.git⟩ on
2025-08-11. (At that time, the date of the most recent commit
that was found in the repository was 2025-08-08.) If you discover
any rendering problems in this HTML version of the page, or you
believe there is a better or more up-to-date source for the page,
or you have corrections or improvements to the information in this
COLOPHON (which is not part of the original manual page), send a
mail to man-pages@man7.org
iproute2 11 Jan 2015Mirror/redirect action in tc(8)
Pages that refer to this page: tc-actions(8), tc-ct(8), tc-ctinfo(8), tc-mpls(8)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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