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# Flowspec (RFC5575)
GoBGP supports [RFC5575](https://tools.ietf.org/html/rfc5575),
[RFC7674](https://tools.ietf.org/html/rfc7674),
[draft-ietf-idr-flow-spec-v6-06](https://tools.ietf.org/html/draft-ietf-idr-flow-spec-v6-06)
and [draft-ietf-idr-flowspec-l2vpn-03](https://tools.ietf.org/html/draft-ietf-idr-flowspec-l2vpn-03).
## Prerequisites
Assume you finished [Getting Started](https://github.com/osrg/gobgp/blob/master/docs/sources/getting-started.md).
## Contents
- [Configuration](#section0)
- [Add Flowspec routes through CLI](#section1)
## <a name="section0"> Configuration
To advertise flowspec routes, enumerate `ipv4-flowspec` to neighbor's
afi-safis like below.
```toml
[global.config]
as = 64512
router-id = "192.168.255.1"
[[neighbors]]
[neighbors.config]
neighbor-address = "10.0.255.1"
peer-as = 64512
[[neighbors.afi-safis]]
[neighbors.afi-safis.config]
afi-safi-name = "ipv4-flowspec"
[[neighbors.afi-safis]]
[neighbors.afi-safis.config]
afi-safi-name = "ipv6-flowspec"
[[neighbors.afi-safis]]
[neighbors.afi-safis.config]
afi-safi-name = "l2vpn-flowspec"
```
## <a name="section1"> Add Flowspec routes through CLI
CLI syntax to add ipv4/ipv6 flowspec rule is
```shell
% global rib add match <MATCH_EXPR> then <THEN_EXPR> -a [ipv4-flowspec|ipv6-flowspec]
<MATCH_EXPR> : { destination <PREFIX> [<OFFSET>] | source <PREFIX> [<OFFSET>] |
protocol <PROTO>... | fragment <FRAGMENT_TYPE> | tcp-flags [!] [=] <TCPFLAG>... |
{ port | destination-port | source-port | icmp-type | icmp-code | packet-length | dscp | label } <ITEM>... }...
<PROTO> : ospf, pim, igp, udp, igmp, tcp, egp, rsvp, gre, ipip, unknown, icmp, sctp, <VALUE>
<FRAGMENT_TYPE> : dont-fragment, is-fragment, first-fragment, last-fragment, not-a-fragment
<TCPFLAG> : U, C, E, F, S, R, P, A
<ITEM> : &?{<|>|>=|<=|==|!=}<value>
<THEN_EXPR> : { accept | discard | rate-limit <value> | redirect <RT> | mark <value> | action { sample | terminal | sample-terminal } | rt <RT>... }...
<RT> : xxx:yyy, xx.xx.xx.xx:yyy, xxx.xxx:yyy, <ipv6_address>:yyy
```
that for l2vpn flowspec rule is
``` shell
% global rib add match <MATCH_EXPR> then <THEN_EXPR> -a [l2vpn-flowspec]
<MATCH_EXPR> : { { destination-mac | source-mac } <MAC> | ether-type <ETHER_TYPE> | { llc-dsap | llc-ssap | llc-control | snap | vid | cos | inner-vid | inner-cos } <ITEM>... }...
<ETHER_TYPE> : arp, vmtp, ipx, snmp, net-bios, xtp, pppoe-discovery, ipv4, rarp, ipv6, pppoe-session, loopback, apple-talk, aarp
<ITEM> : &?{<|>|>=|<=|==|!=}<value>
<THEN_EXPR> : { accept | discard | rate-limit <value> | redirect <RT> | mark <value> | action { sample | terminal | sample-terminal } | rt <RT>... }...
<RT> : xxx:yyy, xx.xx.xx.xx:yyy, xxx.xxx:yyy, <ipv6_address>:yyy
```
### Decimal values and Operators
Gobgp comply with the following draft: https://tools.ietf.org/html/draft-hr-idr-rfc5575bis-03
All decimal values like ports, destination port, source port, procotol number can be married with the following operators:
```
+----+----+----+----------------------------------+
| lt | gt | eq | Resulting operation |
+----+----+----+----------------------------------+
| 0 | 0 | 0 | true (independent of the value) |
| 0 | 0 | 1 | == (equal) |
| 0 | 1 | 0 | > (greater than) |
| 0 | 1 | 1 | >= (greater than or equal) |
| 1 | 0 | 0 | < (less than) |
| 1 | 0 | 1 | <= (less than or equal) |
| 1 | 1 | 0 | != (not equal value) |
| 1 | 1 | 1 | false (independent of the value) |
+----+----+----+----------------------------------+
```
### Examples
```shell
# add a flowspec rule which redirect flows with dst 10.0.0.0/24 and src 20.0.0.0/24 to VRF with RT 10:10
% gobgp global rib -a ipv4-flowspec add match destination 10.0.0.0/24 source 20.0.0.0/24 then redirect 10:10
# add a flowspec rule wich discard flows with dst 2001::2/128 and port equals 80 and with TCP flags not match SA (SYN/ACK) and not match U (URG)
% gobgp global rib -a ipv6-flowspec add match destination 2001::2/128 port '==80' tcp-flags '=!SA&=!U' then discard
# show flowspec table
% gobgp global rib -a ipv4-flowspec
Network Next Hop AS_PATH Age Attrs
*> [destination:10.0.0.0/24][source:20.0.0.0/24] 0.0.0.0 00:00:04 [{Origin: i} {Extcomms: [redirect: 10:10]}]
# add another flowspec rule which discard flows whose ip protocol is tcp and destination port is 80 or greater than or equal to 8080 and lesser than or equal to 8888
% gobgp global rib -a ipv4-flowspec add match protocol tcp destination-port '==80' '>=8080&<=8888' then discard
# add flowspec rule to drop traffic not going to destination port 80, 443 or 22
gobgp global rib -a ipv4-flowspec add match destination 2.2.2.2/32 dest-port '!=80&!=443&!=22' then discard
% gobgp global rib -a ipv4-flowspec
Network Next Hop AS_PATH Age Attrs
*> [destination:10.0.0.0/24][source:20.0.0.0/24] 0.0.0.0 00:03:19 [{Origin: i} {Extcomms: [redirect: 10:10]}]
*> [protocol: tcp][destination-port: ==80 >=8080&<=8888] 0.0.0.0 00:00:03 [{Origin: i} {Extcomms: [discard]}]
# delete a flowspec rule
% gobgp global rib -a ipv4-flowspec del match destination 10.0.0.0/24 source 20.0.0.0/24 then redirect 10:10
% gobgp global rib -a ipv4-flowspec
Network Next Hop AS_PATH Age Attrs
*> [protocol: tcp][destination-port: ==80 >=8080&<=8888] 0.0.0.0 00:00:03 [{Origin: i} {Extcomms: [discard]}]
```
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