tc-csum(8) — Linux manual page

Checksum action in tc(8)          Linux         Checksum action in tc(8)

NAME

       csum - checksum update action

SYNOPSIS

       tc ... action csum UPDATE

       UPDATE := TARGET [ UPDATE ]

       TARGET := { ip4h | icmp | igmp | tcp | udp | udplite | sctp |
               SWEETS }

       SWEETS := { and | or | + }

DESCRIPTION

       The csum action triggers checksum recalculation of specified
       packet headers. It is commonly used to fix incorrect checksums
       after the pedit action has modified the packet content.

OPTIONS

       TARGET Specify which headers to update: IPv4 header (ip4h), ICMP
              header (icmp), IGMP header (igmp), TCP header (tcp), UDP
              header (udp), UDPLite header (udplite) or SCTP header
              (sctp).

       SWEETS These are merely syntactic sugar and ignored internally.

EXAMPLES

       The following performs stateless NAT for incoming packets from
       192.0.2.100 to new destination 198.51.100.1. Assuming these are
       UDP packets, both IP and UDP checksums have to be recalculated:

              # tc qdisc add dev eth0 ingress handle ffff:
              # tc filter add dev eth0 prio 1 protocol ip parent ffff: \
                   u32 match ip src 192.0.2.100/32 flowid :1 \
                   action pedit munge ip dst set 198.51.100.1 pipe \
                   csum ip and udp

SEE ALSO

       tc(8), tc-pedit(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 2015      Checksum action in tc(8)

Pages that refer to this page: tc-actions(8)

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