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Re: Broadcast pings.

  • From: Stephen Balbach
  • Date: Tue Dec 23 11:59:42 1997

block/log broadcast pings:

-------------

access-list 198 deny icmp any 0.0.0.255 255.255.255.0 log

route-map ICMP-DENY permit 10
 match ip address 198

interface ATM3/0
 ip policy route-map ICMP-DENY

-------------

Here's someone working thier way through a CIDR block(source address
removed to protect the inocent):

Dec 13 15:32:01 e1-1.baltimore.mae-east.clark.net 169458: .Dec 13
20:32:00.878: 
%SEC-6-IPACCESSLOGDP: list 198 denied icmp x.x.x.x ->
207.196.61.255 (8/0), 1 packet
Dec 13 15:32:11 e1-1.baltimore.mae-east.clark.net 169459: .Dec 13
20:32:10.410: 
%SEC-6-IPACCESSLOGDP: list 198 denied icmp x.x.x.x ->
207.196.63.255 (8/0), 1 packet
Dec 13 15:32:17 e1-1.baltimore.mae-east.clark.net 169460: .Dec 13
20:32:16.406: 
%SEC-6-IPACCESSLOGDP: list 198 denied icmp x.x.x.x ->
207.196.98.255 (8/0), 1 packet



On Mon, 22 Dec 1997, Joe  Shaw wrote:

> I had a customers link go down because they were the target of a smurf
> attack a few weeks ago, and when I was sniffing the link to find out what
> was going on, I found tons of packets coming from root nameservers, .gov
> sites, and other places.  If I hadn't been at a terminal, I'd have done a
> better job of logging them when it happened.  As it stands, I just turned
> off ICMP into my routers for a few hours and all was well.  What I would
> have given to have had a dedicated sniffer so I could have done a better
> job of logging.
> 
> Regards,
> Joe Shaw - jshaw@insync.net
> NetAdmin - Insync Internet Services
> Fortune for the day: "Speak softly and carry a +6 two-handed sword."
> 
> On Mon, 22 Dec 1997, Jamie Scheinblum wrote:
> 
> > Has anyone seen an increase of broadcast pings, where the source route
> > appears to be from a nameserver?
> > 
> > We took a look through our access-list logs, and it seems all of the
> > attempted attacks during the last few days have had an IP-source of a
> > nameserver.
> > 
> > Just thought it was curious.
> > 
> > Best regards,
> > 
> > Jamie Scheinblum - FASTNET(tm) / You Tools Corporation
> > jamie@fast.net (610)954-5200 http://www.fast.net/
> > FASTNET - Business and Personal Internet Solutions
> > 
> 





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