tc-csum(8) — Linux manual page


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

NAME         top

       csum - checksum update action

SYNOPSIS         top

       tc ... action csum UPDATE


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

       SWEETS := { and | or | + }

DESCRIPTION         top

       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         top

       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

       SWEETS These are merely syntactic sugar and ignored internally.

EXAMPLES         top

       The following performs stateless NAT for incoming packets from to new destination 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 flowid :1 \
                   action pedit munge ip dst set pipe \
                   csum ip and udp

SEE ALSO         top

       tc(8), tc-pedit(8)

COLOPHON         top

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iproute2                       11 Jan 2015      Checksum action in tc(8)

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