de-peering for security sake
list at satchell.net
Sat Dec 26 15:09:28 UTC 2015
On 12/26/2015 06:19 AM, Mike Hammett wrote:
> How much is an acceptable standard to the community? Individual /32s
> ( or /64s)? Some tipping point where 50% of a /24 (or whatever it's
> IPv6 equivalent would be) has made your naughty list that you block
> the whole prefix?
My gauge is volume of obnoxious traffic. When I get lots of SSH probes
from a /32, I block the /32. When I get lots of SSH probes across a
range of a /24, I block the /24.
When I see that the bad traffic has caused me to block multiple /24s, I
will block the entire allocation.
By "lots" I mean hundreds or more. When the criminals try to bust my
door down, I take stops to stop them.
Ditto with attempts to relay mail through my mail servers.
My goal isn't to reduce traffic. My goal is to stop irresponsible
people from finding a rat-hole to do things I don't authorize them to
do. Defense in depth.
This is in addition to selecting the TCP and UDP ports carefully that I
expose to the outside world. Indeed, I have separate ACLs for inbound,
outbound, and DMZ ports. So, I've limited service from the inside to
the outside to this:
> # ---originated by LAN host to Internet
> FORWARD_TCP="ftp ssh snmp telnet smtp smtps submission domain http https ntp nicname rwhois pop3 pop3s imap imaps radius"
> FORWARD_TCP="$FORWARD_TCP 465 8008 webcache 8443 8888 snpp rsync"
> # xmpp-client
> FORWARD_TCP="$FORWARD_TCP 5222 5223 8002"
> # Microsoft Notification Protocol (msnp) [Messenger]
> FORWARD_TCP="$FORWARD_TCP 1863"
> # Microsoft PPTP
> FORWARD_TCP="$FORWARD_TCP 1723"
> # Timbuktu client, Service Ports 1-4
> FORWARD_TCP="$FORWARD_TCP 407 1417:1420"
> # memoq
> FORWARD_TCP="$FORWARD_TCP 2705"
> FORWARD_UDP="domain ntp snmp 407 443 500 1419 1701 1812 4500 snmp 3389 10000 55555 "
Your client base and my client base differ. I make NNAP difficult to
use against the world from my people. But I don't hamstring them; if
they want access to an outside service, they have but to ask.
I also terminate spammers.
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