Re: [exim] Warning to Linux postmasters

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著者: Wakko Warner
日付:  
To: exim-users
題目: Re: [exim] Warning to Linux postmasters
Tony Finch wrote:
> Make sure you have the line
>     mdns off
> in /etc/host.conf on your incoming SMTP servers.


IIRC, /etc/host.conf is for libc5. libc6 uses /etc/nsswitch.conf

> One of my colleagues in our network engineering team discovered today that
> ppswitch was spewing multicast packets, much to our surprise. It turns out
> that recent versions of glibc have quietly added support for multicast DNS
> to the resolver. Multicast DNS is part of Apple's zeroconf networking
> system (aka Bonjour, previously known as Rendezvous), and it takes over
> responsibility for host names ending in .local. See it in action by typing
> strace ping foo.local and observe it sending a DNS query to the class D
> multicast address 224.0.0.251.


# ping x.local
ping: unknown host x.local
#

TCPdump:
00:14:36.580336 IP 192.168.2.7.32796 > 198.32.64.12.53: 47461% [1au] A? x.local. (36)
00:14:36.704271 IP 198.32.64.12.53 > 192.168.2.7.32796: 47461 NXDomain*- 0/1/1 (111)

libc6 v2.6-3 (debian)

Maybe it doesn't happen with debian's libc6?
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