bgpq3 - bgp filtering automation for Cisco and Juniper routers
bgpq3 [-h host[:port]] [-S sources] [-EP] [-f asn | -F fmt | -G asn] [-2346ABbDdJjpsX] [-r len] [-R len] [-m max] [-W len] OBJECTS [...] EXCEPT OBJECTS
The bgpq3 utility used to generate Cisco and Juniper prefix-lists, extended access-lists, policy-statement terms and as-path lists based on RADB data.
The options are as follows:
Allow routes registered for as23456 (transition-as) (default: false)
Assume that your device is asn32-capable.
Generate IPv4 prefix/access-lists (default).
Generate IPv6 prefix/access-lists (IPv4 by default).
Try to aggregate generated filters as much as possible (not all output formats supported).
Generate output in OpenBGPD format (default: Cisco).
Generate output in BIRD format (default: Cisco).
Enable some debugging output.
Use asdot notation for Cisco as-path access-lists.
Generate extended access-list (Cisco) or policy-statement term using route-filters (Juniper).
Generate input as-path access-list for adjacent as AS number.
Generate output in user-defined format.
Generate output as-path access-list.
Host running IRRD database (default: whois.radb.net).
Generate config for Juniper (default: Cisco).
Generate output in JSON format (default: Cisco).
Maximum length of accepted prefixes (default: 32 for IPv4, 128 for IPv6).
Extra match conditions for Juniper route-filters. See the examples section.
Name of generated configuration stanza.
Limit recursion depth when expanding. This slows bgpq3 a bit, but sometimes
is a useful feature to prevent generated filters from growing too big.
Enable use of private ASNs and ASNs used for documentation purpose only (default: disabled).
Generate prefix-list (default behaviour, flag added for backward compatibility only).
Allow more-specific routes with masklen starting with specified length.
Allow more-specific routes up to specified masklen too. (Please, note: objects with prefix-length greater than specified length will be always allowed.)
Generate sequence numbers in IOS-style prefix-lists.
Use specified sources only (recommended: RADB,RIPE,APNIC).
Disable pipelining. (not recommended)
Generate as-path strings of a given length maximum (0 for infinity).
Generate config for Cisco IOS XR devices (plain IOS by default).
OBJECTS means networks (in prefix format), autonomous systems, as-sets and
route-sets. If multiple objects are specified they will be merged.
You can exclude autonomous sets, as-sets and route-sets found during expansion from future expansion.
Generating named Juniper prefix-filter for AS20597:
user@host:~>bgpq3 -Jl eltel AS20597
policy-options {
replace:
prefix-list eltel {
81.9.0.0/20;
81.9.32.0/20;
81.9.96.0/20;
81.222.128.0/20;
81.222.192.0/18;
85.249.8.0/21;
85.249.224.0/19;
89.112.0.0/19;
89.112.4.0/22;
89.112.32.0/19;
89.112.64.0/19;
217.170.64.0/20;
217.170.80.0/20;
}
}
For Cisco we can use aggregation (-A) flag to make this prefix-filter more compact:
user@host:~>bgpq3 -Al eltel AS20597
no ip prefix-list eltel
ip prefix-list eltel permit 81.9.0.0/20
ip prefix-list eltel permit 81.9.32.0/20
ip prefix-list eltel permit 81.9.96.0/20
ip prefix-list eltel permit 81.222.128.0/20
ip prefix-list eltel permit 81.222.192.0/18
ip prefix-list eltel permit 85.249.8.0/21
ip prefix-list eltel permit 85.249.224.0/19
ip prefix-list eltel permit 89.112.0.0/18 ge 19 le 19
ip prefix-list eltel permit 89.112.4.0/22
ip prefix-list eltel permit 89.112.64.0/19
ip prefix-list eltel permit 217.170.64.0/19 ge 20 le 20
and, as you see, prefixes 89.112.0.0/19 and 89.112.32.0/19 now aggregated
into single entry
ip prefix-list eltel permit 89.112.0.0/18 ge 19 le 19.
Well, for Juniper we can generate even more interesting policy-statement,
using -M <extra match conditions>, -r <len>, -R <len> and hierarchical
names:
user@host:~>bgpq3 -AJEl eltel/specifics -r 29 -R 32 -M "community blackhole" AS20597
policy-options {
policy-statement eltel {
term specifics {
replace:
from {
community blackhole;
route-filter 81.9.0.0/20 prefix-length-range /29-/32;
route-filter 81.9.32.0/20 prefix-length-range /29-/32;
route-filter 81.9.96.0/20 prefix-length-range /29-/32;
route-filter 81.222.128.0/20 prefix-length-range /29-/32;
route-filter 81.222.192.0/18 prefix-length-range /29-/32;
route-filter 85.249.8.0/21 prefix-length-range /29-/32;
route-filter 85.249.224.0/19 prefix-length-range /29-/32;
route-filter 89.112.0.0/17 prefix-length-range /29-/32;
route-filter 217.170.64.0/19 prefix-length-range /29-/32;
}
}
}
}
generated policy-option term now allows more-specific routes in range /29 - /32 for eltel networks if they marked with community 'blackhole' (defined elsewhere in configuration).
Of course, bgpq3 supports IPv6 (-6):
user@host:~>bgpq3 -6l as-retn-6 AS-RETN6
no ipv6 prefix-list as-retn-6
ipv6 prefix-list as-retn-6 permit 2001:7fb:fe00::/48
ipv6 prefix-list as-retn-6 permit 2001:7fb:fe01::/48
[....]
and ASN32
user@host:~>bgpq3 -J3f 112 AS-SPACENET
policy-options {
replace:
as-path-group NN {
as-path a0 "^112(112)*$";
as-path a1 "^112(.)*(1898|5539|8495|8763|8878|12136|12931|15909)$";
as-path a2 "^112(.)*(21358|23456|23600|24151|25152|31529|34127|34906)$";
as-path a3 "^112(.)*(35052|41720|43628|44450|196611)$";
}
}
see AS196611 in the end of the list ? That's AS3.3 in 'asplain' notation.
If your router does not support ASN32 (yet) you should not use switch -3, and the result will be next:
user@host:~>bgpq3 -f 112 AS-SPACENET
no ip as-path access-list NN
ip as-path access-list NN permit ^112( 112)*$
ip as-path access-list NN permit ^112( [0-9]+)* (1898|5539|8495|8763)$
ip as-path access-list NN permit ^112( [0-9]+)* (8878|12136|12931|15909)$
ip as-path access-list NN permit ^112( [0-9]+)* (21358|23456|23600|24151)$
ip as-path access-list NN permit ^112( [0-9]+)* (25152|31529|34127|34906)$
ip as-path access-list NN permit ^112( [0-9]+)* (35052|41720|43628|44450)$
AS196611 is no more in the list, however, AS23456 (transition AS) would
have been added to list if it were not present.
If you want to generate configuration not for routers, but for some other programs/systems, you may use user-defined formatting, like in example below:
user@host:~>bgpq3 -F "ipfw add pass all from %n/%l to any\\n" as3254
ipfw add pass all from 62.244.0.0/18 to any
ipfw add pass all from 91.219.29.0/24 to any
ipfw add pass all from 91.219.30.0/24 to any
ipfw add pass all from 193.193.192.0/19 to any
Recognized format characters: '%n' - network, '%l' - mask length, '%N' - object name, '%m' - object mask and '%i' - inversed mask. Recognized escape characters: '\n' - new line, '\t' - tabulation. Please note that no new lines inserted automatically after each sentence, you have to add them into format string manually, elsewhere output will be in one line (sometimes it makes sense):
user@host:~>bgpq3 -6F "%n/%l; " as-eltel
2001:1b00::/32; 2620:4f:8000::/48; 2a04:bac0::/29; 2a05:3a80::/48;
When everything is OK, bgpq3 generates result to standard output and
exits with status == 0. In case of errors they are printed to stderr and
program exits with non-zero status.
To improve bgpq3 performance when expanding extra-large AS-SETs you
shall tune OS settings to enlarge TCP send buffer.
FreeBSD can be tuned in the following way:
sysctl -w net.inet.tcp.sendbuf_max=2097152
Linux can be tuned in the following way:
sysctl -w net.ipv4.tcp_window_scaling=1
sysctl -w net.core.rmem_max=2097152
sysctl -w net.core.wmem_max=2097152
sysctl -w net.ipv4.tcp_rmem="4096 87380 2097152"
sysctl -w net.ipv4.tcp_wmem="4096 65536 2097152"
Please note that generated prefix-lists may not fit your router's limitations. For example, JunOS supports only 85,325 prefixes in each prefix-list 4.
- Routing Arbiter
- draft-michaelson-4byte-as-representation-05.txt for information on 'asdot' and 'asplain' notations.
- Cisco documentation for information on Cisco implementation of ASN32.
- JunOS prefix-lists limitation
Alexandre Snarskii snar@snar.spb.ru