On 1/23/20 11:38 AM, Tom Eastep wrote: > On 1/23/20 10:53 AM, Eero Volotinen wrote: >> https://www.google.fi/amp/s/blog.cloudtrooper.net/2017/09/19/setting-up-31-interfaces-and-bgp-on-a-centos-machine/amp/ >> >> it should work. follow the guide. >> > > I suspect that there will be anomalies with Shorewall, however, because > both IP addresses will be broadcast addresses (one the network address > and the other the network broadcast address). > > teastep@Asus:~/shorewall/web$ shorewall ipcalc 68.140.187.76/31 > CIDR=68.140.187.76/31 > NETMASK=255.255.255.254 > NETWORK=68.140.187.76 > BROADCAST=68.140.187.77 > teastep@Asus:~/shorewall/web$ > > So, for example, the dropBcast action will drop all traffic to either > address. That can be fixed, but it will take a change to the Shorewall > code to special-case /31. > > Also, the 'nosmurfs' interface option cannot be used as it will cause > all packets with the gateway address as the source IP to be dropped. >
I've taken another look and the above issues should not present major
problems. There will be a minor problem in that multiple rules for
address 255.255.255.255 can be generated, because that is the broadcast
address reported by 'ip -f inet addr show'.
root@gateway:~# ip addr ls dev br2
15: br2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state
UNKNOWN group default qlen 1000
link/ether 92:45:6b:91:0e:91 brd ff:ff:ff:ff:ff:ff
inet 172.20.4.2/31 brd 255.255.255.255 scope global br2
valid_lft forever preferred_lft forever
inet6 fe80::9045:6bff:fe91:e91/64 scope link
valid_lft forever preferred_lft forever
root@gateway:~#
So please let us know if you encounter any major problem...
Thanks,
-Tom
--
Tom Eastep \ Q: What do you get when you cross a mobster
Shoreline, \ with an international standard?
Washington, USA \ A: Someone who makes you an offer you
http://shorewall.org \ can't understand
\________________________________________
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