[BGP] How to Block Multiple ASN With 1 rule

RouterOS Forwarding Protocols
1

I would like to ask about blocking multiple asn without filtering each time.

Currently, I have BGP connection with multiple ISPs, each ISP will announce other ISPs’ asn. My problem is that I don’t want some asn.

Currently, I block like this, I will do this every time there is an unwanted asn.

rule=“if (bgp-as-path XXXXX) {reject;}”

But what I want is, is there a Filter or something? To block in a single rule, but multiple asn.

(For example, blocking with address-list in firewall) Can filter in bgp do something like this? Like (asn-list) something like this.

I work in ISP (Internet Service Provider).

Sorry if my English is not good. :smiley:

Thank you all for helping me this time. :slight_smile:

2

You may use

/routing/filter/num-list

like this:

/routing filter num-list
add comment=some_bad_as disabled=no list=BAD-AS range=200993
add comment=another_bad_as disabled=no list=BAD-AS range=200994

/routing filter rule
add chain=some_chain disabled=no rule="if (bgp-as-path [[:BAD-AS:]]) {reject}"

for the num-list range you may use a not single, but a range of ASNs:

add comment="RFC 6996" disabled=no list=BOGON-AS range=4200000000-4294967294
3

Thankyou somuch i will try it :slight_smile:

4

rule=“if (bgp-as-path XXXXX || bgp-as-path AAAA || bgp-as-path BBBB || bgp-as-path CCCC) {reject;};”
Or as others suggested, numbered lists.

5

Thankyou Somuch this is work Perfect !!

6

This is work for me check status route is filtered Perfect thankyou all



/routing filter num-list
add comment="Deny-ASN" list=Deny-ASN range=10000-20000


/routing filter rule
add chain=your_chain disabled=no rule="if (bgp-as-path [[:Deny-ASN:]]) {reject}"