[BBLISA] Amazon EC2 Oddly Rejecting Very Specific IP Addresses

[Dean Anderson]

There is no reason to think that 75.101.149.255 is a broadcast address.  
x.y.z.255 is the broadcast for a x.y.z/24, but we don't know this is a
/24. Any IP address could be a /32.  I have web servers that use all 256
IP addresss in the last octet. (You put them on loopback interfaces as
/32)

lo:255    Link encap:Local Loopback
          inet addr:130.105.21.255  Mask:255.255.255.255
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:17281535 errors:0 dropped:0 overruns:239 frame:0
          TX packets:8963801 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:2491380274 (2375.9 Mb)  TX bytes:256009920 (244.

But no one besides Amazon would be filtering Amazon's broadcast
addresses anyway.


		--Dean

On Tue, 13 Apr 2010, R Gary Cutbill wrote:

> Just a guess....
> I've seen routers configured to block forwarding to broadcast addresses. 
> Perhaps
> the router is (mis-)interpreting the amazon address as a broadcast 
> address because
> it ends in 255?
> 
> I'd start by checking the logs on the router.
> 
> -R. Gary
> 
> Richard 'Doc' Kinne wrote:
> > Folks:
> >
> > I'd like to see if anyone has heard of circumstances like this before.
> >
> > I have a server on the Amazon EC2 cloud running a website service. 
> > This is largely working well.
> >
> > However I have one customer that cannot get to it from a specific 
> > address. The IP address of my server is 75.101.149.255. When you do a 
> > "whois" on this it comes up as:
> >
> > OrgName:    Amazon.com, Inc.
> > OrgID:      AMAZO-4
> > Address:    Amazon Web Services, Elastic Compute Cloud, EC2
> > Address:    1200 12th Avenue South
> > City:       Seattle
> > StateProv:  WA
> > PostalCode: 98144
> > Country:    US
> >
> > which makes perfect sense.
> >
> > We originally thought that Amazon might be blocking access to the 
> > service to specific IP or IP ranges, but based on traceroutes that 
> > didn't seem to make sense.
> >
> > When my customer tries to do a traceroute from his place to my server 
> > he doesn't even get out of his router:
> >
> > tracert 75.101.149.255
> > Tracing route to [75.101.149.255] over a maximum of 30 hops:
> >   1     1 ms    <1 ms    <1 ms  www.routerlogin.com 
> > <http://www.routerlogin.com> [10.1.1.1]
> >   2     *        *        *     Request timed out.
> >
> > I've never seen anything like that before. I can understand things 
> > timing out when you get to the Amazon area, but timing out before you 
> > even get into the Net proper? That doesn't make sense to me. 
> > Everything else seems to work properly from his location from what 
> > he's telling me.
> >
> > There is a part of me that thinks there may be something wrong somehow 
> > with my customer's address. When I do a "whois" on the customer's 
> > address it comes back as being owned by IANA, which doesn't seem right 
> > at all. Also when I try a traceroute to his address *I* don't get past 
> > my router in two totally separate locations (work, that has one ISP, 
> > and home, which has a very different ISP).
> >
> > I've never quite seen anything act like this before and I'm not quite 
> > sure how to puzzle it out.
> >
> > Does anyone have any thoughts?
> > -- 
> > Doc Kinne, [KQR]
> > (From the Gmail Web Interface)
> > ------------------------------------------------------------------------
> >
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> > bblisa at bblisa.org
> > http://www.bblisa.org/mailman/listinfo/bblisa
> 
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> 

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