[CentOS] OT: what are all these probes from my firewall log????

Sat Aug 18 20:48:24 UTC 2012
Robert Nichols <rnicholsNOSPAM at comcast.net>

On 08/18/2012 10:01 AM, fred smith wrote:
> On Sat, Aug 18, 2012 at 09:20:56AM -0500, Robert Nichols wrote:
>> Those are BOOTP responses from your ISP's DHCP server to clients requesting
>> an IP address.  They have to be broadcast because the client does not yet
>> have an IP address.  Go yell at whoever set up your firewall to log these
>> harmless packets that are a necessary part of dynamic IPv4 address
>> assignment on a shared medium.
>>         SPT=67                source port = BOOTP server
>>         DPT=68                dest port = BOOTP client
>>         DST=   dest address = Broadcast
> that implies that there are a WHOLE LOT of systems served by this provider
> that are doing dhcp requests, given the volume of these things I'm seeing.
> they're arriving at rates ranging from 4-5 a second, to 1-2 a minute,
> mostly in the one every 1-5 seconds rate.
> My firewall is filtering them, which is good. and while there are a lot
> of them it isn't enough to make a dent in my incoming bandwidth. Were I
> still on dialup or DSL, it might be.
> The firewall is the built-in firewall in my Asus router. the UI doesn't
> give much flexibility in what it logs (basically you can log none, dropped,
> accepted, or all--I've chosen to log dropped). Of course, I could open a
> shell on the router and hack the iptables rules, but I'd just as soon not.
> thanks for the reply!

FWIW, I average about 9 of those per minute on my cable segment.  That's
194000 packets counted by my own (non-logging!) iptables rule in the 15+
days this system has been up.

Bob Nichols     "NOSPAM" is really part of my email address.
                 Do NOT delete it.