[Pkg-utopia-maintainers] Bug#517160: avahi-daemon: reflector advertises link-local addresses

[Rob Leslie]

Package: avahi-daemon
Version: 0.6.23-3lenny1
Severity: normal

When the avahi-daemon reflector is enabled, the daemon may copy RRSets
containing link-local addresses (169.254.0.0/16, fe80::/10) to other
interfaces, where they are patently useless.  This sometimes manifests a
problem whereby it is not possible to reach certain endpoints on the
non-local network segments.

For example, AirPort Extreme devices like to advertise their link-local
addresses together with any others it has:

% dig @224.0.0.251 -p 5353 airport-extreme.local. ANY

; <<>> DiG 9.5.1-P1 <<>> @224.0.0.251 -p 5353 airport-extreme.local. ANY
; (1 server found)
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 60456
;; flags: qr aa; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;airport-extreme.local.		IN	ANY

;; ANSWER SECTION:
AirPort-Extreme.local. 10	IN	AAAA	fe80::21b:63ff:fef5:93ab
AirPort-Extreme.local. 10	IN	A	10.0.1.151
AirPort-Extreme.local. 10	IN	A	169.254.228.74

;; Query time: 0 msec
;; SERVER: 10.0.1.151#5353(224.0.0.251)
;; WHEN: Wed Feb 25 18:36:49 2009
;; MSG SIZE  rcvd: 125

In this case 10.0.1.151 is the only address that is valid for reaching the
device from any segment.  When this RRSet is reflected onto non-local network
segments, other hosts may try to reach the device using the link-local
address(es) and fail.  This happens, for example, with Apple's AirPort
Utility which seems to rely on an address chosen at random from the available
RRs.

I think it would be better if avahi-daemon could filter RRSets to remove
link-local addresses when reflecting them onto other network segments.

Thanks.


-- System Information:
Debian Release: 5.0
  APT prefers stable
  APT policy: (500, 'stable')
Architecture: i386 (i686)

Kernel: Linux 2.6.26-1-686 (SMP w/2 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/bash

Versions of packages avahi-daemon depends on:
ii  adduser                3.110             add and remove users and groups
ii  bind9-host [host]      1:9.5.1.dfsg.P1-1 Version of 'host' bundled with BIN
ii  dbus                   1.2.1-5           simple interprocess messaging syst
ii  libavahi-common3       0.6.23-3lenny1    Avahi common library
ii  libavahi-core5         0.6.23-3lenny1    Avahi's embeddable mDNS/DNS-SD lib
ii  libc6                  2.7-18            GNU C Library: Shared libraries
ii  libcap2                2.11-2            support for getting/setting POSIX.
ii  libdaemon0             0.12-2lenny1      lightweight C library for daemons 
ii  libdbus-1-3            1.2.1-5           simple interprocess messaging syst
ii  libexpat1              2.0.1-4           XML parsing C library - runtime li
ii  lsb-base               3.2-20            Linux Standard Base 3.2 init scrip

Versions of packages avahi-daemon recommends:
ii  libnss-mdns                   0.10-3     NSS module for Multicast DNS name 

Versions of packages avahi-daemon suggests:
pn  avahi-autoipd                 <none>     (no description available)

-- no debconf information