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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 | SWEETS }

       SWEETS := { and | or | + }

DESCRIPTION
       The  csum action triggers checksum recalculation of specified packet headers. It is commonly used after packet
       editing using the pedit action to fix for then incorrect checksums.

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

       SWEETS These are merely syntactic sugar and ignored internally.

EXAMPLES
       The  following  performs stateless NAT for incoming packets from 192.168.1.100 to new destination 18.52.86.120
       (0x12345678 in hex). 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 eth0 prio 1 protocol ip parent ffff: \
                   u32 match ip src 192.168.1.100/32 flowid :1 \
                   action pedit munge ip dst set 0x12345678 pipe \
                   csum ip and udp


SEE ALSO
       tc(8), tc-pedit(8)



iproute2                                             11 Jan 2015                             Checksum action in tc(8)