Add configuration commands and brief example of firewall Flowtables. Also re-add commands for firewall state policies, which now can eb found under <global-options> section

1 files changed, 138 insertions, 2 deletions

diff --git a/docs/configuration/firewall/flowtables.rst b/docs/configuration/firewall/flowtables.rst
index 8b44a9b9..bc7b9212 100644
--- a/docs/configuration/firewall/flowtables.rst
+++ b/docs/configuration/firewall/flowtables.rst
@@ -1,4 +1,4 @@
-:lastproofread: 2023-11-08
+:lastproofread: 2023-12-26
 
 .. _firewall-flowtables-configuration:
 
@@ -13,7 +13,7 @@ Overview
 ********
 
 In this section there's useful information of all firewall configuration that
-can be done regarding flowtables
+can be done regarding flowtables.
 
 .. cfgcmd:: set firewall flowtables ...
 
@@ -50,3 +50,139 @@ flowtable (flowtable miss), the packet follows the classic IP forwarding path.
 
 .. note:: **Flowtable Reference:**
    https://docs.kernel.org/networking/nf_flowtable.html
+
+
+***********************
+Flowtable Configuration
+***********************
+
+In order to use flowtables, the minimal configuration needed includes:
+
+   * Create flowtable: create flowtable, which includes the interfaces
+     that are going to be used by the flowtable.
+
+   * Create firewall rule: create a firewall rule, setting action to
+     ``offload`` and using desired flowtable for ``offload-target``.
+
+Creating a flow table:
+
+.. cfgcmd:: set firewall flowtable <flow_table_name> interface <iface>
+
+   Define interfaces to be used in the flowtable.
+
+.. cfgcmd:: set firewall flowtable <flow_table_name> description <text>
+
+Provide a description to the flow table.
+
+.. cfgcmd:: set firewall flowtable <flow_table_name> offload
+   <hardware | software>
+
+   Define type of offload to be used by the flowtable: ``hardware`` or
+   ``software``. By default, ``software`` offload is used.
+
+.. note:: **Hardware offload:** should be supported by the NICs used.
+
+Creating rules for using flow tables:
+
+.. cfgcmd:: set firewall [ipv4 | ipv4] forward filter rule <1-999999>
+   action offload
+
+   Create firewall rule in forward chain, and set action to ``offload``.
+
+.. cfgcmd:: set firewall [ipv4 | ipv4] forward filter rule <1-999999>
+   offload-target <flowtable>
+
+   Create firewall rule in forward chain, and define which flowtbale
+   should be used. Only applicable if action is ``offload``.
+
+*********************
+Configuration Example
+*********************
+
+Things to be considred in this setup:
+
+   * Two interfaces are going to be used in the flowtables: eth0 and eth1
+
+   * Minumum firewall ruleset is provided, which includes some filtering rules,
+     and appropiate rules for using flowtable offload capabilities.
+
+As described, first packet will be evaluated by all the firewall path, so
+desired connection should be explicitely accepted. Same thing should be taken
+into account for traffic in reverse order. In most cases state policies are
+used in order to accept connection in reverse patch.
+
+We will only accept traffic comming from interface eth0, protocol tcp and
+destination port 1122. All other traffic traspassing the router should be
+blocked.
+
+Commands
+--------
+
+.. code-block:: none
+
+      set firewall flowtable FT01 interface 'eth0'
+      set firewall flowtable FT01 interface 'eth1'
+      set firewall ipv4 forward filter default-action 'drop'
+      set firewall ipv4 forward filter rule 10 action 'offload'
+      set firewall ipv4 forward filter rule 10 offload-target 'FT01'
+      set firewall ipv4 forward filter rule 10 state 'established'
+      set firewall ipv4 forward filter rule 10 state 'related'
+      set firewall ipv4 forward filter rule 20 action 'accept'
+      set firewall ipv4 forward filter rule 20 state 'established'
+      set firewall ipv4 forward filter rule 20 state 'related'
+      set firewall ipv4 forward filter rule 110 action 'accept'
+      set firewall ipv4 forward filter rule 110 destination address '192.0.2.100'
+      set firewall ipv4 forward filter rule 110 destination port '1122'
+      set firewall ipv4 forward filter rule 110 inbound-interface name 'eth0'
+      set firewall ipv4 forward filter rule 110 protocol 'tcp'
+
+Explanation
+-----------
+
+Analysis on what happens for desired connection:
+
+   1. First packet is received on eht0, with destination address 192.0.2.100,
+   protocol tcp and destination port 1122. Assume such destination address is
+   reachable through interface eth1.
+
+   2. Since this is the first packet, connection status of this connection,
+   so far is **new**. So neither rule 10 nor 20 are valid.
+
+   3. Rule 110 is hit, so connection is accepted.
+
+   4. Once answer from server 192.0.2.100 is seen in opposite direction,
+   connection state will be triggered to **established**, so this reply is
+   accepted in rule 10.
+
+   5. Second packet for this connection is received by the router. Since
+   connection state is **established**, then rule 10 is hit, and a new entry
+   in the flowtable FT01 is added for this connection.
+
+   6. All subsecuent packets will skip traditional path, and will be offloaded
+   and will use the **Fast Path**.
+
+Checks
+------
+
+It's time to check conntrack table, to see if any connection was accepted,
+and if was properly offloaded
+
+.. code-block:: none
+
+      vyos@FlowTables:~$ show firewall ipv4 forward filter
+      Ruleset Information
+      
+      ---------------------------------
+      ipv4 Firewall "forward filter"
+      
+      Rule     Action    Protocol      Packets    Bytes  Conditions
+      -------  --------  ----------  ---------  -------  ----------------------------------------------------------------
+      10       offload   all                 8      468  ct state { established, related }  flow add @VYOS_FLOWTABLE_FT01
+      20       accept    all                 8      468  ct state { established, related }  accept
+      110      accept    tcp                 2      120  ip daddr 192.0.2.100 tcp dport 1122 iifname "eth0"  accept
+      default  drop      all                 7      420
+      
+      vyos@FlowTables:~$ sudo conntrack -L | grep tcp
+      conntrack v1.4.6 (conntrack-tools): 5 flow entries have been shown.
+      tcp      6 src=198.51.100.100 dst=192.0.2.100 sport=41676 dport=1122 src=192.0.2.100 dst=198.51.100.100 sport=1122 dport=41676 [OFFLOAD] mark=0 use=2
+      vyos@FlowTables:~$