bin/42487: Invalid default hop limit in rtadvd

[martti.kuparinen%iki.fi@localhost]

>Number:         42487
>Category:       bin
>Synopsis:       Invalid default hop limit in rtadvd
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    bin-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Dec 21 07:45:00 +0000 2009
>Originator:     Martti Kuparinen
>Release:        NetBSD 5.0_STABLE
>Organization:
>Environment:
        
        
System: NetBSD p130.mydomain.net 5.0_STABLE NetBSD 5.0_STABLE 
(P130_MYDOMAIN_NET) #0: Sun Dec 20 13:56:08 EET 2009 
root%p130.mydomain.net@localhost:/usr/src/sys/arch/amd64/compile/P130_MYDOMAIN_NET
 amd64
Architecture: x86_64
Machine: amd64
>Description:

Our rtadvd.conf(5) (as found on 5.0 and 5.99.22) says

  The following items are for ICMPv6 router advertisement message header.
  These items can be omitted, then rtadvd will use the default values.

  chlim    The value for Cur Hop Limit field. The default value is 64.


However, http://tools.ietf.org/html/rfc4861#section-6.1.2 says

   A node MUST silently discard any received Router Advertisement
   messages that do not satisfy all of the following validity checks:
   ...
      - The IP Hop Limit field has a value of 255, i.e., the packet
        could not possibly have been forwarded by a router.


So, a node receiving RA from a NetBSD router (with default options) should
ignore the RA. In real life, our NetBSD and Linux hosts are happy but...

>How-To-Repeat:
>Fix:

>Unformatted: