<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN">
<HTML>
<HEAD>
<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1">
<META NAME="Generator" CONTENT="MS Exchange Server version 5.5.2653.12">
<TITLE>BGP filters for rfc 1918 and other nasties</TITLE>
</HEAD>
<BODY>
<BR>
<P><FONT SIZE=2>I have been doing some looking around for a decent access-list or prefix-list to start my inbound BGP filters. I have found quite a few flawed examples, but none that look solid.. What do you use for ingress filters?</FONT></P>
<P><FONT SIZE=2>Found an interesting link in an ancient (12/97) Nanog post. Those who have coffee and BGP for breakfast should take a peek.</FONT></P>
<P><FONT SIZE=2><A HREF="http://www.employees.org/~tbates/cidr-report.html" TARGET="_blank">http://www.employees.org/~tbates/cidr-report.html</A></FONT>
<BR><FONT SIZE=2> </FONT>
<BR><FONT SIZE=2> </FONT>
<BR><FONT SIZE=2><A HREF="http://www.lucentnps.com/knowledge/whitepapers/bgp_main_isp.asp" TARGET="_blank">http://www.lucentnps.com/knowledge/whitepapers/bgp_main_isp.asp</A> </FONT>
<BR><FONT SIZE=2>missing 172.16/12 ??? </FONT>
</P>
<P><FONT SIZE=2>access-list 100 deny ip 127.0.0.0 0.255.255.255 255.0.0.0 0.255.255.255</FONT>
<BR><FONT SIZE=2>access-list 100 deny ip 10.0.0.0 0.255.255.255 255.0.0.0 0.255.255.255</FONT>
<BR><FONT SIZE=2>access-list 100 deny ip 192.168.0.0 0.0.255.255 255.255.0.0 0.0.255.255</FONT>
<BR><FONT SIZE=2>access-list 100 deny ip 192.0.2.0 0.0.0.255 255.255.255.0 0.0.0.255</FONT>
<BR><FONT SIZE=2>access-list 100 deny ip 128.0.0.0 0.0.255.255 255.255.0.0 0.0.255.255</FONT>
<BR><FONT SIZE=2>access-list 100 deny ip 191.255.0.0 0.0.255.255 255.255.0.0 0.0.255.255</FONT>
<BR><FONT SIZE=2>access-list 100 deny ip 192.0.0.0 0.0.0.255 255.255.255.0 0.0.0.255</FONT>
<BR><FONT SIZE=2>access-list 100 deny ip 223.255.255.0 0.0.0.255 255.255.255.0 0.0.0.255</FONT>
<BR><FONT SIZE=2>access-list 100 deny ip 224.0.0.0 31.255.255.255 224.0.0.0 31.255.255.255</FONT>
<BR><FONT SIZE=2>access-list 100 deny ip any 255.255.255.128 0.0.0.127</FONT>
<BR><FONT SIZE=2>access-list 100 deny ip 0.0.0.0 0.255.255.255 0.0.0.0 255.255.255.255</FONT>
<BR><FONT SIZE=2>access-list 100 permit any any</FONT>
</P>
<P><FONT SIZE=2><A HREF="http://www.cymru.com/~robt/Docs/Articles/secure-bgp-template.html" TARGET="_blank">http://www.cymru.com/~robt/Docs/Articles/secure-bgp-template.html</A> </FONT>
</P>
<P><FONT SIZE=2>ip prefix-list bogons description Bogon networks we won't accept.</FONT>
<BR><FONT SIZE=2>ip prefix-list bogons seq 5 deny 0.0.0.0/8 le 32</FONT>
<BR><FONT SIZE=2>ip prefix-list bogons seq 10 deny 1.0.0.0/8 le 32</FONT>
<BR><FONT SIZE=2>ip prefix-list bogons seq 15 deny 2.0.0.0/8 le 32</FONT>
<BR><FONT SIZE=2>ip prefix-list bogons seq 20 deny 10.0.0.0/8 le 32</FONT>
<BR><FONT SIZE=2>ip prefix-list bogons seq 25 deny 23.0.0.0/8 le 32</FONT>
<BR><FONT SIZE=2>ip prefix-list bogons seq 30 deny 31.0.0.0/8 le 32</FONT>
<BR><FONT SIZE=2>ip prefix-list bogons seq 35 deny 67.0.0.0/8 le 32</FONT>
<BR><FONT SIZE=2>ip prefix-list bogons seq 40 deny 68.0.0.0/6 le 32</FONT>
<BR><FONT SIZE=2>ip prefix-list bogons seq 45 deny 72.0.0.0/6 le 32</FONT>
<BR><FONT SIZE=2>ip prefix-list bogons seq 50 deny 76.0.0.0/6 le 32</FONT>
<BR><FONT SIZE=2>ip prefix-list bogons seq 55 deny 80.0.0.0/6 le 32</FONT>
<BR><FONT SIZE=2>ip prefix-list bogons seq 60 deny 84.0.0.0/6 le 32</FONT>
<BR><FONT SIZE=2>ip prefix-list bogons seq 65 deny 88.0.0.0/6 le 32</FONT>
<BR><FONT SIZE=2>ip prefix-list bogons seq 70 deny 92.0.0.0/6 le 32</FONT>
<BR><FONT SIZE=2>ip prefix-list bogons seq 75 deny 96.0.0.0/6 le 32</FONT>
<BR><FONT SIZE=2>ip prefix-list bogons seq 80 deny 100.0.0.0/6 le 32</FONT>
<BR><FONT SIZE=2>ip prefix-list bogons seq 85 deny 104.0.0.0/6 le 32</FONT>
<BR><FONT SIZE=2>ip prefix-list bogons seq 90 deny 108.0.0.0/6 le 32</FONT>
<BR><FONT SIZE=2>ip prefix-list bogons seq 95 deny 112.0.0.0/6 le 32</FONT>
<BR><FONT SIZE=2>ip prefix-list bogons seq 100 deny 116.0.0.0/6 le 32</FONT>
<BR><FONT SIZE=2>ip prefix-list bogons seq 105 deny 120.0.0.0/6 le 32</FONT>
<BR><FONT SIZE=2>ip prefix-list bogons seq 110 deny 124.0.0.0/7 le 32</FONT>
<BR><FONT SIZE=2>ip prefix-list bogons seq 115 deny 126.0.0.0/8 le 32</FONT>
<BR><FONT SIZE=2>ip prefix-list bogons seq 120 deny 127.0.0.0/8 le 32</FONT>
<BR><FONT SIZE=2>ip prefix-list bogons seq 125 deny 169.254.0.0/16 le 32</FONT>
<BR><FONT SIZE=2>ip prefix-list bogons seq 130 deny 172.16.0.0/12 le 32</FONT>
<BR><FONT SIZE=2>ip prefix-list bogons seq 135 deny 192.0.2.0/24 le 32</FONT>
<BR><FONT SIZE=2>ip prefix-list bogons seq 140 deny 192.168.0.0/16 le 32</FONT>
<BR><FONT SIZE=2>ip prefix-list bogons seq 145 deny 198.18.0.0/16 le 32</FONT>
<BR><FONT SIZE=2>ip prefix-list bogons seq 150 deny 201.0.0.0/8 le 32</FONT>
<BR><FONT SIZE=2>ip prefix-list bogons seq 155 deny 223.255.255.0/24 le 32</FONT>
<BR><FONT SIZE=2>ip prefix-list bogons seq 160 deny 224.0.0.0/3 le 32</FONT>
<BR><FONT SIZE=2>! Allow all prefixes up to /27. Your mileage may vary,</FONT>
<BR><FONT SIZE=2>! so adjust this to fit your specific requirements.</FONT>
<BR><FONT SIZE=2>ip prefix-list bogons seq 170 permit 0.0.0.0/0 le 27</FONT>
</P>
<BR>
<BR>
<BR>
<BR>
<P><FONT SIZE=2>-----Original Message-----</FONT>
<BR><FONT SIZE=2>From: Chris Davis [<A HREF="mailto:chris.davis@computerjobs.com">mailto:chris.davis@computerjobs.com</A>]</FONT>
<BR><FONT SIZE=2>Sent: February 22, 2001 3:39 PM</FONT>
<BR><FONT SIZE=2>To: 'nanog@merit.edu'</FONT>
<BR><FONT SIZE=2>Subject: rfc 1918?</FONT>
</P>
<BR>
<BR>
<BR>
<P><FONT SIZE=2>Hello,</FONT>
</P>
<P><FONT SIZE=2>Does anyone know why I get inbound packets from 10.x.x.x coming from my ISP,</FONT>
<BR><FONT SIZE=2>UUNet? They're just headed for a webserver, so it's not likely that they're</FONT>
<BR><FONT SIZE=2>up to no good.</FONT>
<BR><FONT SIZE=2>This seems to violate rfc 1918. Am I crazy?</FONT>
</P>
<P><FONT SIZE=2>Feb 22 15:29:48 computerjobs-gw 353094: Feb 22 20:30:10.439 UTC:</FONT>
<BR><FONT SIZE=2>%SEC-6-IPACCESSLOGP: list 135 denied tcp 10.10.5.18(62438) -></FONT>
<BR><FONT SIZE=2>63.67.217.184(80), 1 packet </FONT>
<BR><FONT SIZE=2>Feb 22 15:30:02 computerjobs-gw 353095: Feb 22 20:30:24.024 UTC:</FONT>
<BR><FONT SIZE=2>%SEC-6-IPACCESSLOGP: list 135 denied tcp 10.10.5.18(62440) -></FONT>
<BR><FONT SIZE=2>63.67.217.184(80), 1 packet </FONT>
<BR><FONT SIZE=2>Feb 22 15:30:06 computerjobs-gw 353096: Feb 22 20:30:28.168 UTC:</FONT>
<BR><FONT SIZE=2>%SEC-6-IPACCESSLOGP: list 135 denied tcp 10.10.5.18(62455) -></FONT>
<BR><FONT SIZE=2>63.67.217.184(80), 1 packet </FONT>
</P>
</BODY>
</HTML>