[j-nsp] Help Needed for Bonjour Routing/OSX Clients

[Jonathan Lassoff]

On Thu, May 10, 2012 at 2:54 AM, Phil Mayers <p.mayers at imperial.ac.uk>wrote:

> On 09/05/12 22:55, Jonathan Lassoff wrote:
>
>  I've gotten this to work in the past, but it ended up being a LOT more
>> work
>> than just using DNS names and routing (which I've subsequently done each
>> time).
>>
>
> Out of curiosity, how did this work? Isn't most mDNS traffic TTL=1?


I don't know about all the various implementations out there (of if the
standard says anything), but my modern-ish OSX box does 255:

v6:
    Internet Protocol Version 6, Src: fe80::xxxx:xxff:xxxx:xxxx
(fe80::xxxx:xxff:xxxx:xxxx), Dst: ff02::fb (ff02::fb)
        0110 .... = Version: 6
            [0110 .... = This field makes the filter "ip.version == 6"
possible: 6]
        .... 0000 0000 .... .... .... .... .... = Traffic class: 0x00000000
            .... 0000 00.. .... .... .... .... .... = Differentiated
Services Field: Default (0x00000000)
            .... .... ..0. .... .... .... .... .... = ECN-Capable Transport
(ECT): Not set
            .... .... ...0 .... .... .... .... .... = ECN-CE: Not set
        .... .... .... 0000 0000 0000 0000 0000 = Flowlabel: 0x00000000
        Payload length: 35
        Next header: UDP (0x11)
        Hop limit: 255
        Source: fe80::xxxx:xxff:xxxx:xxxx (fe80::xxxx:xxff:xxxx:xxxx)
        [Source SA MAC: xx:xx:xx:xx:xx:xx (xx:xx:xx:xx:xx:xx)]
        Destination: ff02::fb (ff02::fb)
    User Datagram Protocol, Src Port: 5353 (5353), Dst Port: 5353 (5353)
        Source port: 5353 (5353)
        Destination port: 5353 (5353)
        Length: 35
        Checksum: 0x4aa1 [validation disabled]
            [Good Checksum: False]
            [Bad Checksum: False]
    Domain Name System (query)
    ......

and the v4 case:
    Ethernet II, Src: xx:xx:xx:xx:xx:xx (xx:xx:xx:xx:xx:xx), Dst:
01:00:5e:00:00:fb (01:00:5e:00:00:fb)
        Destination: 01:00:5e:00:00:fb (01:00:5e:00:00:fb)
            Address: 01:00:5e:00:00:fb (01:00:5e:00:00:fb)
            .... ...1 .... .... .... .... = IG bit: Group address
(multicast/broadcast)
            .... ..0. .... .... .... .... = LG bit: Globally unique address
(factory default)
        Source: xx:xx:xx:xx:xx:xx (xx:xx:xx:xx:xx:xx)
            Address: xx:xx:xx:xx:xx:xx (xx:xx:xx:xx:xx:xx)
            .... ...0 .... .... .... .... = IG bit: Individual address
(unicast)
            .... ..0. .... .... .... .... = LG bit: Globally unique address
(factory default)
        Type: IP (0x0800)
    Internet Protocol Version 4, Src: nn.nn.nn.nn (nn.nn.nn.nn), Dst:
224.0.0.251 (224.0.0.251)
        Version: 4
        Header length: 20 bytes
        Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00:
Not-ECT (Not ECN-Capable Transport))
            0000 00.. = Differentiated Services Codepoint: Default (0x00)
            .... ..00 = Explicit Congestion Notification: Not-ECT (Not
ECN-Capable Transport) (0x00)
        Total Length: 55
        Identification: 0xd6ca (54986)
        Flags: 0x00
            0... .... = Reserved bit: Not set
            .0.. .... = Don't fragment: Not set
            ..0. .... = More fragments: Not set
        Fragment offset: 0
        Time to live: 255
        Protocol: UDP (17)
        Header checksum: 0x82ad [correct]
            [Good: True]
            [Bad: False]
        Source: nn.nn.nn.nn (nn.nn.nn.nn)
        Destination: 224.0.0.251 (224.0.0.251)
    User Datagram Protocol, Src Port: 5353 (5353), Dst Port: 5353 (5353)
        Source port: 5353 (5353)
        Destination port: 5353 (5353)
        Length: 35
        Checksum: 0x2886 [validation disabled]
            [Good Checksum: False]
            [Bad Checksum: False]
    Domain Name System (query)
....

Cheers,
jof