{"id":3442,"date":"2022-12-20T17:02:41","date_gmt":"2022-12-20T20:02:41","guid":{"rendered":"http:\/\/lode.uno\/linux-man\/index.php\/2022\/12\/20\/checksum-action-in-tc-man8\/"},"modified":"2022-12-20T17:02:41","modified_gmt":"2022-12-20T20:02:41","slug":"checksum-action-in-tc-man8","status":"publish","type":"post","link":"https:\/\/lode.uno\/linux-man\/2022\/12\/20\/checksum-action-in-tc-man8\/","title":{"rendered":"Checksum action in tc (man8)"},"content":{"rendered":"

Checksum action in tc<\/h1>\n

NAME<\/a>
SYNOPSIS<\/a>
DESCRIPTION<\/a>
OPTIONS<\/a>
EXAMPLES<\/a>
SEE ALSO<\/a> <\/p>\n

\n

NAME <\/a> <\/h2>\n

csum – checksum update action<\/p>\n

SYNOPSIS <\/a> <\/h2>\n

tc<\/b> … action csum<\/b> UPDATE<\/i><\/p>\n

UPDATE<\/i> := TARGET<\/i> [ UPDATE<\/i> ]<\/p>\n

TARGET<\/i> := { ip4h<\/b> | icmp<\/b> | igmp<\/b> | tcp<\/b> | udp<\/b> | udplite<\/b> | sctp<\/b> | SWEETS<\/i> }<\/p>\n

SWEETS<\/i> := { and<\/b> | or<\/b> | +<\/b> }<\/p>\n

DESCRIPTION <\/a> <\/h2>\n

The csum<\/b> action triggers checksum recalculation of specified packet headers. It is commonly used to fix incorrect checksums after the pedit<\/b> action has modified the packet content.<\/p>\n

OPTIONS <\/a> <\/h2>\n\n\n\n
<\/td>\n\n

TARGET<\/i><\/p>\n<\/td>\n

<\/td>\n\n

Specify which headers to update: IPv4 header (ip4h<\/b>), ICMP header (icmp<\/b>), IGMP header (igmp<\/b>), TCP header (tcp<\/b>), UDP header (udp<\/b>), UDPLite header (udplite<\/b>) or SCTP header (sctp<\/b>).<\/p>\n<\/td>\n<\/tr>\n

<\/td>\n\n

SWEETS<\/b><\/p>\n<\/td>\n

<\/td>\n\n

These are merely syntactic sugar and ignored internally.<\/p>\n<\/td>\n<\/tr>\n<\/table>\n

EXAMPLES <\/a> <\/h2>\n

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:<\/p>\n

# tc qdisc add dev eth0 ingress handle ffff:
# tc filter add dev eth0 prio 1 protocol ip parent ffff: <\/p>\n\n\n\n\n
<\/td>\n\n

u32 match ip src 192.0.2.100\/32 flowid :1 <\/p>\n<\/td>\n<\/tr>\n

<\/td>\n\n

action pedit munge ip dst set 198.51.100.1 pipe <\/p>\n<\/td>\n<\/tr>\n

<\/td>\n\n

csum ip and udp<\/p>\n<\/td>\n<\/tr>\n<\/table>\n

SEE ALSO <\/a> <\/h2>\n

tc<\/b>(8), tc-pedit<\/b>(8)<\/p>\n

\n","protected":false},"excerpt":{"rendered":"

csum – checksum update action <\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2],"tags":[5,52,4,568],"class_list":["post-3442","post","type-post","status-publish","format-standard","hentry","category-8-administracion-del-sistema","tag-5","tag-administracion","tag-man8","tag-tc-csum"],"gutentor_comment":0,"_links":{"self":[{"href":"https:\/\/lode.uno\/linux-man\/wp-json\/wp\/v2\/posts\/3442","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/lode.uno\/linux-man\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/lode.uno\/linux-man\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/lode.uno\/linux-man\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/lode.uno\/linux-man\/wp-json\/wp\/v2\/comments?post=3442"}],"version-history":[{"count":0,"href":"https:\/\/lode.uno\/linux-man\/wp-json\/wp\/v2\/posts\/3442\/revisions"}],"wp:attachment":[{"href":"https:\/\/lode.uno\/linux-man\/wp-json\/wp\/v2\/media?parent=3442"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/lode.uno\/linux-man\/wp-json\/wp\/v2\/categories?post=3442"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/lode.uno\/linux-man\/wp-json\/wp\/v2\/tags?post=3442"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}