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freebsd 7.1 default ipv6 gateway problem

Discussion in 'Networking' started by yavuzg, Jun 5, 2009.

  1. yavuzg

    yavuzg New Member

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    Hi,

    I have network consists of 2 computers(say A and B) and a router.

    When I use rtsol in A, I can get the global scope ipv6 address and the default gateway properly.

    But when I send fake router advertisement messages from B, A accepts advertisements and makes fake address as default gateway. Ä°s this the expected behaviour?

    What is the procedure for selecting default router?

    thanks in advance...

    before I send fake messages from B

    Code:
    # netstat -finet6 -rn
    
    Routing tables
    Internet6:
    Destination                       Gateway                       Flags      Netif Expire
    default                           fe80::***:cb0(real gateway)  UG         fxp0
    
    
    after I send fake messages from B,

    Code:
    # netstat -finet6 -rn
    
    Routing tables
    Internet6:
    Destination                       Gateway                       Flags      Netif Expire
    default                           fe80::***:a(fake gateway)  UG         fxp0
    
    
    my configuration is:

    Code:
    # sysctl -a | grep ip6
    net.inet6.ip6.forwarding: 0
    net.inet6.ip6.redirect: 1
    net.inet6.ip6.hlim: 64
    net.inet6.ip6.maxfragpackets: 4112
    net.inet6.ip6.accept_rtadv: 1
    net.inet6.ip6.keepfaith: 0
    net.inet6.ip6.log_interval: 5
    net.inet6.ip6.hdrnestlimit: 15
    net.inet6.ip6.dad_count: 1
    net.inet6.ip6.auto_flowlabel: 1
    net.inet6.ip6.defmcasthlim: 1
    net.inet6.ip6.gifhlim: 30
    net.inet6.ip6.kame_version: FreeBSD
    net.inet6.ip6.use_deprecated: 1
    net.inet6.ip6.rr_prune: 5
    net.inet6.ip6.v6only: 1
    net.inet6.ip6.rtexpire: 3600
    net.inet6.ip6.rtminexpire: 10
    net.inet6.ip6.rtmaxcache: 128
    net.inet6.ip6.use_tempaddr: 0
    net.inet6.ip6.temppltime: 86400
    net.inet6.ip6.tempvltime: 604800
    net.inet6.ip6.auto_linklocal: 1
    net.inet6.ip6.prefer_tempaddr: 0
    net.inet6.ip6.use_defaultzone: 0
    net.inet6.ip6.maxfrags: 4112
    net.inet6.ip6.mcast_pmtu: 0
    
    my system:
    Code:
    # uname -a
    FreeBSD pcname 7.1-RELEASE FreeBSD 7.1-RELEASE #0: Thu Jan  1 14:37:25 UTC 2009     root@logan.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC  i386
    
     
  2. SirDice

    SirDice Moderator Staff Member Moderator

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    Unfortunately, yes.

    Running a properly setup rtadvd on the gateway or use dhcp6.

    NB fe80:: addresses are link-local, non-routable addresses.
     
  3. yavuzg

    yavuzg New Member

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    According to RFC 2461 "6.3.6. Default Router Selection" section, I think there is no need to update default router in my case.
     
  4. SirDice

    SirDice Moderator Staff Member Moderator

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    I've been playing with IPv6 for some time now and I see no reason why a client wouldn't pick up any 'new' router advertisements. How would the client know the gateway was changed? What if there appeared a 'better' route? As far as I understood it the purpose of using rtsol/rtadvd is to make the whole network more dynamic. The downside of this would be rogue router advertisements ruining it.
     
  5. yavuzg

    yavuzg New Member

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    Thanks for the answer. You are true, a client has to accept rtadvd messages in some manner. I want to learn the exact mechanism behind the router selection of freebsd network implementation.

    in rfc 2461, section 6.3.6 says that:
    I think freebsd use round-robin fashion and this is the reason of my router change...