1ct action in tc(8)                   Linux                  ct action in tc(8)
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NAME

6       ct - tc connection tracking action
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SYNOPSIS

9       tc  ... action ct commit [ force ] [ zone ZONE ] [ mark MASKED_MARK ] [
10               label MASKED_LABEL ] [ nat NAT_SPEC ]
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12       tc ... action ct [ nat ] [ zone ZONE ]
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14       tc ... action ct clear
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DESCRIPTION

18       The ct action is a tc action for sending packets and  interacting  with
19       the netfilter conntrack module.
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21       It can (as shown in the synopsis, in order):
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23       Send  the packet to conntrack, and commit the connection, while config‐
24       uring a 32bit mark, 128bit label, and src/dst nat.
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26       Send the packet to conntrack, which will mark the packet with the  con‐
27       nection's  state and configured metadata (mark/label), and execute pre‐
28       vious configured nat.
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30       Clear the packet's of previous connection tracking state.
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OPTIONS

34       zone ZONE
35              Specify a conntrack zone number on which to send the  packet  to
36              conntrack.
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38       mark MASKED_MARK
39              Specify  a  masked  32bit  mark  to set for the connection (only
40              valid with commit).
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42       label MASKED_LABEL
43              Specify a masked 128bit label to set for  the  connection  (only
44              valid with commit).
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46       nat NAT_SPEC
47              Where   NAT_SPEC   :=   {src|dst}   addr   addr1[-addr2]   [port
48              port1[-port2]]
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50              Specify src/dst and range of nat to configure for the connection
51              (only valid with commit).
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53              src/dst - configure src or dst nat
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55              addr1/addr2 - IPv4/IPv6 addresses
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57              port1/port2 - Port numbers
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59       nat    Restore any previous configured nat.
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61       clear  Remove  any  conntrack  state and metadata (mark/label) from the
62              packet (must only option specified).
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64       force  Forces conntrack direction for  a  previously  commited  connec‐
65              tions, so that current direction will become the original direc‐
66              tion (only valid with commit).
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EXAMPLES

70       Example showing natted firewall in conntrack zone 2, and conntrack mark
71       usage:
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73       #Add ingress qdisc on eth0 and eth1 interfaces
74       $ tc qdisc add dev eth0 handle ingress
75       $ tc qdisc add dev eth1 handle ingress
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77       #Setup filters on eth0, allowing opening new connections in zone 2, and doing src nat + mark for each new connection
78       $ tc filter add dev eth0 ingress prio 1 chain 0 proto ip flower ip_proto tcp ct_state -trk \
79       action ct zone 2 pipe action goto chain 2
80       $ tc filter add dev eth0 ingress prio 1 chain 2 proto ip flower ct_state +trk+new \
81       action ct zone 2 commit mark 0xbb nat src addr 5.5.5.7 pipe action mirred egress redirect dev eth1
82       $ tc filter add dev eth0 ingress prio 1 chain 2 proto ip flower ct_zone 2 ct_mark 0xbb ct_state +trk+est \
83       action ct nat pipe action mirred egress redirect dev eth1
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85       #Setup filters on eth1, allowing only established connections of zone 2 through, and reverse nat (dst nat in this case)
86       $ tc filter add dev eth1 ingress prio 1 chain 0 proto ip flower ip_proto tcp ct_state -trk \
87       action ct zone 2 pipe action goto chain 1
88       $ tc filter add dev eth1 ingress prio 1 chain 1 proto ip flower ct_zone 2 ct_mark 0xbb ct_state +trk+est \
89       action ct nat pipe action mirred egress redirect dev eth0
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SEE ALSO

94       tc(8), tc-flower(8) tc-mirred(8)
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AUTHORS

97       Paul Blakey <paulb@mellanox.com>
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99       Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
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101       Yossi Kuperman <yossiku@mellanox.com>
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105iproute2                          14 May 2020               ct action in tc(8)