.TH "Checksum action in tc" 8 "11 Jan 2015" "iproute2" "Linux"

.SH NAME
csum - checksum update action
.SH SYNOPSIS
.in +8
.ti -8
.BR tc " ... " "action csum"
.I UPDATE

.ti -8
.IR UPDATE " := " TARGET " [ " UPDATE " ]"

.ti -8
.IR TARGET " := { "
.BR ip4h " |"
.BR icmp " |"
.BR igmp " |"
.BR tcp " |"
.BR udp " |"
.BR udplite " |"
.IR SWEETS " }"

.ti -8
.IR SWEETS " := { "
.BR and " | " or " | " + " }"
.SH DESCRIPTION
The
.B csum
action triggers checksum recalculation of specified packet headers. It is
commonly used after packet editing using the
.B pedit
action to fix for then incorrect checksums.
.SH OPTIONS
.TP
.I TARGET
Specify which headers to update: IPv4 header
.RB ( ip4h ),
ICMP header
.RB ( icmp ),
IGMP header
.RB ( igmp ),
TCP header
.RB ( tcp ),
UDP header
.RB ( udp ") or"
UDPLite header
.RB ( udplite ).
.TP
.B SWEETS
These are merely syntactic sugar and ignored internally.
.SH SEE ALSO
.BR tc (8),
.BR tc-pedit (8)