145 lines
2.7 KiB
HTML
145 lines
2.7 KiB
HTML
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML><HEAD><TITLE>Man page of Checksum action in tc</TITLE>
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</HEAD><BODY>
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<H1>Checksum action in tc</H1>
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Section: Linux (8)<BR>Updated: 11 Jan 2015<BR><A HREF="#index">Index</A>
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<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
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<P>
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<A NAME="lbAB"> </A>
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<H2>NAME</H2>
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csum - checksum update action
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<BR>
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<B>tc</B> ... <B>action csum</B>
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<I>UPDATE</I>
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<P>
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<BR>
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<I>UPDATE</I> := <I>TARGET</I> [ <I>UPDATE</I> ]
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<P>
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<BR>
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<I>TARGET</I> := {
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<B>ip4h</B> |
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<B>icmp</B> |
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<B>igmp</B> |
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<B>tcp</B> |
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<B>udp</B> |
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<B>udplite</B> |
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<B>sctp</B> |
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<I>SWEETS</I> }
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<P>
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<BR>
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<I>SWEETS</I> := {
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<B>and</B> | <B>or</B> | <B>+</B> }
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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The
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<B>csum</B>
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action triggers checksum recalculation of specified packet headers. It is
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commonly used to fix incorrect checksums after the
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<B>pedit</B>
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action has modified the packet content.
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<A NAME="lbAE"> </A>
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<H2>OPTIONS</H2>
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<DL COMPACT>
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<DT id="1"><I>TARGET</I>
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<DD>
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Specify which headers to update: IPv4 header
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(<B>ip4h</B>),
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ICMP header
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(<B>icmp</B>),
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IGMP header
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(<B>igmp</B>),
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TCP header
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(<B>tcp</B>),
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UDP header
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(<B>udp</B>),
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UDPLite header
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(<B>udplite</B>) or
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SCTP header
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(<B>sctp</B>).
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<DT id="2"><B>SWEETS</B>
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<DD>
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These are merely syntactic sugar and ignored internally.
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</DL>
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<A NAME="lbAF"> </A>
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<H2>EXAMPLES</H2>
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The following performs stateless NAT for incoming packets from 192.0.2.100 to
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new destination 198.51.100.1. Assuming these are UDP
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packets, both IP and UDP checksums have to be recalculated:
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<P>
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<DL COMPACT><DT id="3"><DD>
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# tc qdisc add dev eth0 ingress handle ffff:
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# tc filter add dev eth0 prio 1 protocol ip parent ffff: \
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<TT> </TT>u32 match ip src 192.0.2.100/32 flowid :1 \<BR>
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<TT> </TT>action pedit munge ip dst set 198.51.100.1 pipe \<BR>
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<TT> </TT>csum ip and udp<BR>
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</DL>
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<P>
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<A NAME="lbAG"> </A>
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<H2>SEE ALSO</H2>
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<B><A HREF="/cgi-bin/man/man2html?8+tc">tc</A></B>(8),
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<B><A HREF="/cgi-bin/man/man2html?8+tc-pedit">tc-pedit</A></B>(8)
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<P>
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<HR>
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<A NAME="index"> </A><H2>Index</H2>
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<DL>
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<DT id="4"><A HREF="#lbAB">NAME</A><DD>
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<DT id="5"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="6"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="7"><A HREF="#lbAE">OPTIONS</A><DD>
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<DT id="8"><A HREF="#lbAF">EXAMPLES</A><DD>
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<DT id="9"><A HREF="#lbAG">SEE ALSO</A><DD>
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</DL>
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<HR>
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This document was created by
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<A HREF="/cgi-bin/man/man2html">man2html</A>,
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using the manual pages.<BR>
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Time: 00:06:17 GMT, March 31, 2021
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</BODY>
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</HTML>
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