On Tue, Jan 22, 2002 at 01:57:07PM -0600, J.F. Noonan wrote:
On Tue, 22 Jan 2002 at 12:34pm Joe Abley wrote:
On Mon, Jan 21, 2002 at 05:53:16PM -0500, Stephen Griffin wrote:
I'm curious about how many networks completely filter all traffic to any ip address ending in either ".0" or ".255".
I heard recently that Windows 2000 will refuse to send packets to addresses with the least-significant octet 255, if the most- significant octet indicates the address lies in a pre-CIDR class C. So, for example, 192.168.0.255 would be unreachable from a windows 2000 machine, regardless of the fact that it might be a legitimate host numbered within 192.168.0.0/23.
Not true. M$ is guilty of many evil things, but not this one.
I just tried this. This is not exhaustive. I may well have made some kind of some screw-up. Interpret as you will. Contents may have settled in transit. NetBSD 1.5.2 i386 FreeBSD 4.5-PRERELEASE | | ---+------------+------------+---- | Win2k SP3 I configured the following addresses: NetBSD: 192.168.0.1/23, 192.168.0.255/23 FreeBSD: 192.168.0.20/23 Win2k: 192.168.0.30/23 FreeBSD box can ping 192.168.0.1. FreeBSD box can ping 192.168.0.255. NetBSD box can ping 192.168.0.20. NetBSD box can ping 192.168.0.30 (tcpdump shows the NetBSD box is using a source of 192.168.0.1 for these pings). Win2k box can ping 192.168.0.1. Win2k box can ping 192.168.0.20. Win2k cannot ping 192.168.0.255: C:\>ping 192.168.0.255 Pinging 192.168.0.255 with 32 bytes of data: Request timed out. Request timed out. Request timed out. Request timed out. Ping statistics for 192.168.0.255: Packets: Sent = 4, Received = 0, Lost = 4 (100% loss), Approximate round trip times in milli-seconds: Minimum = 0ms, Maximum = 0ms, Average = 0ms C:\> NetBSD box is receiving the requests, however, and replying to them. tcpdump shows: 15:30:39.753003 192.168.0.20 > 192.168.0.255: icmp: echo request 15:30:39.753307 192.168.0.255 > 192.168.0.20: icmp: echo reply 15:30:41.228742 192.168.0.20 > 192.168.0.255: icmp: echo request 15:30:41.229053 192.168.0.255 > 192.168.0.20: icmp: echo reply 15:30:42.230249 192.168.0.20 > 192.168.0.255: icmp: echo request 15:30:42.230555 192.168.0.255 > 192.168.0.20: icmp: echo reply 15:30:43.231735 192.168.0.20 > 192.168.0.255: icmp: echo request 15:30:43.232046 192.168.0.255 > 192.168.0.20: icmp: echo reply So, the Windows box seems to behave differently when dealing with the particular address ending in 255 that I tried. I guess the rule of thumb when numbering devices which need to coexist with Windows is "avoid 255". Joe