phpman > man > tc-csum(8)

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 recalcu‐
       lated:

              # 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)



iproute2                                     11 Jan 2015                    Checksum action in tc(8)