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Re: Broadcast ping

At 01:26 AM 5/26/01 -0500, Jonathan Daugherty wrote:
>When I ping the private LAN bcast address behind my firewall, all machines
send packets
>except my roommate's win2k pro box.  All my boxes are debian / redhat
boxes.  Anyone know
>why this machine is not responding to my bcast pings?

Because it is set not to. I don't know the details of why it is set that
way, but not responding to broadcast pings is a commonplace security
strategy. On my own LAN, for example, 3 Linux (Debian) hosts do respond to
broadcast pings, while a fourth, a Win95 host, and a Win98 host, do not.

Broadcast pings are not a very reliable way to find out what is out there.
On Linux systems, firewall rules can block them, as can setting
/proc/sys/net/ipv4/icmp_echo_ignore_broadcasts . I imagine Windows systems
have similar flexibility.

------------------------------------"Never tell me the odds!"---
Ray Olszewski                                        -- Han Solo
Palo Alto, CA           	 	         ray@comarre.com        

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