tc-mirred(8) — Linux manual page

Mirror/redirect action in tc(8)   Linux  Mirror/redirect action in tc(8)

NAME

       mirred - mirror/redirect action

SYNOPSIS

       tc ... action mirred DIRECTION ACTION [ index INDEX ] TARGET

       DIRECTION := { ingress | egress }

       TARGET := { DEV | BLOCK }

       DEV := dev DEVICENAME

       BLOCK := blockid BLOCKID

       ACTION := { mirror | redirect }

DESCRIPTION

       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).

OPTIONS

       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.

EXAMPLES

       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

LIMITATIONS

       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.

SEE ALSO

       tc(8), tc-u32(8)

COLOPHON

       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
       2024-06-14.  (At that time, the date of the most recent commit
       that was found in the repository was 2024-06-11.)  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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