• anyone know who sell a old style Ethernet Hub?

    From Todd@110:110/2002 to All on Sat Oct 4 02:20:01 2014
    Hi All,

    I need to do some network monitoring with Wireshark.
    (modbus/tcp).

    I need an old fashioned hub (not a switch) to
    put between an appliance and a pump so I can see
    what is actually happening.

    Problem: all I can find are switches. Those
    don't work with Wireshark.

    Anyone know of a real hub out there. Only need three
    ports, but am not picky about more than that.

    Prefer 100 Base-T, but can live with 10-base-T

    Many thanks,
    -T

    --- MBSE BBS v1.0.4 (GNU/Linux-i386)
    * Origin: A noiseless patient Spider (110:110/2002@linuxnet)
  • From Richard Kettlewell@110:110/2002 to All on Sat Oct 4 07:48:57 2014
    Todd <Todd@invalid.invalid> writes:
    I need to do some network monitoring with Wireshark.
    (modbus/tcp).

    I need an old fashioned hub (not a switch) to
    put between an appliance and a pump so I can see
    what is actually happening.

    Problem: all I can find are switches. Those
    don't work with Wireshark.

    Anyone know of a real hub out there. Only need three
    ports, but am not picky about more than that.

    Prefer 100 Base-T, but can live with 10-base-T

    No idea. If you can’t find one, if you have a Linux box with at least
    two ethernet ports you should be able to bridge them together, put it
    between your two endpoints, and monitor the traffic on that.

    --
    http://www.greenend.org.uk/rjk/

    --- MBSE BBS v1.0.4 (GNU/Linux-i386)
    * Origin: Anjou (110:110/2002@linuxnet)
  • From Joe The Smoe@110:110/2002 to All on Sat Oct 4 08:33:19 2014
    On 04/10/2014 04:20, Todd wrote:
    Hi All,

    I need to do some network monitoring with Wireshark.
    (modbus/tcp).

    I need an old fashioned hub (not a switch) to
    put between an appliance and a pump so I can see
    what is actually happening.

    Problem: all I can find are switches. Those
    don't work with Wireshark.

    You can use a switch that has port mirroring feature.


    Anyone know of a real hub out there. Only need three
    ports, but am not picky about more than that.

    Be careful about duplex setting when using a hub (always half duplex)!
    If you have forced full duplex on one (or more) host(s), collisions will
    occur and will not be noticed by anyone, no retransmission will occur
    and packets that collided will be dropped silently because of at least a
    wrong CRC.


    Prefer 100 Base-T, but can live with 10-base-T

    Many thanks,
    -T


    --- MBSE BBS v1.0.4 (GNU/Linux-i386)
    * Origin: Guest of ProXad - France (110:110/2002@linuxnet)
  • From Mike Scott@110:110/2002 to All on Sat Oct 4 16:19:16 2014
    On 04/10/14 09:33, Joe The Smoe wrote:
    On 04/10/2014 04:20, Todd wrote:
    Hi All,

    I need to do some network monitoring with Wireshark.
    (modbus/tcp).

    I need an old fashioned hub (not a switch) to
    put between an appliance and a pump so I can see
    what is actually happening.

    Problem: all I can find are switches. Those
    don't work with Wireshark.

    You can use a switch that has port mirroring feature.


    Anyone know of a real hub out there. Only need three
    ports, but am not picky about more than that.

    Be careful about duplex setting when using a hub (always half duplex)!
    If you have forced full duplex on one (or more) host(s), collisions will occur and will not be noticed by anyone, no retransmission will occur
    and packets that collided will be dropped silently because of at least a wrong CRC.

    ? Not a problem I ever experienced.

    How about http://www.amazon.co.uk/D-Link-DE-805TP-5-port-Ethernet-10Mbps/dp/B0000687B5

    by the way?




    Prefer 100 Base-T, but can live with 10-base-T

    Many thanks,
    -T



    --
    Mike Scott (unet2 <at> [deletethis] scottsonline.org.uk)
    Harlow Essex England

    --- MBSE BBS v1.0.4 (GNU/Linux-i386)
    * Origin: Scott family (110:110/2002@linuxnet)
  • From Todd@110:110/2002 to All on Sat Oct 4 22:41:03 2014
    On 10/03/2014 07:20 PM, Todd wrote:
    Hi All,

    I need to do some network monitoring with Wireshark.
    (modbus/tcp).

    I need an old fashioned hub (not a switch) to
    put between an appliance and a pump so I can see
    what is actually happening.

    Problem: all I can find are switches. Those
    don't work with Wireshark.

    Anyone know of a real hub out there. Only need three
    ports, but am not picky about more than that.

    Prefer 100 Base-T, but can live with 10-base-T

    Many thanks,
    -T

    Found on in my junk box. yippee!


    --- MBSE BBS v1.0.4 (GNU/Linux-i386)
    * Origin: A noiseless patient Spider (110:110/2002@linuxnet)
  • From Ant@1:0/0 to All on Sun Oct 5 07:45:54 2014
    Craig's List, eBay, etc.? I got rid of my Netgear hub years ago since it sucked compared to switches.


    On 10/3/2014 7:20 PM PT, Todd typed:

    Hi All,

    I need to do some network monitoring with Wireshark.
    (modbus/tcp).

    I need an old fashioned hub (not a switch) to
    put between an appliance and a pump so I can see
    what is actually happening.

    Problem: all I can find are switches. Those
    don't work with Wireshark.

    Anyone know of a real hub out there. Only need three
    ports, but am not picky about more than that.

    Prefer 100 Base-T, but can live with 10-base-T

    Many thanks,
    -T
    --
    "I go out of my way to avoid stepping on ants." --Terry McGovern,
    daughter of Senator George and Eleanor McGovern, subject of the book
    "Terry by her father"
    /\___/\ Ant(Dude) @ http://antfarm.ma.cx (Personal Web Site)
    / /\ /\ \ Ant's Quality Foraged Links: http://aqfl.net
    | |o o| |
    \ _ / If crediting, then use Ant nickname and AQFL URL/link.
    ( ) If e-mailing, then axe ANT from its address if needed.
    Ant is currently not listening to any songs on this computer.

    --- MBSE BBS v1.0.4 (GNU/Linux-i386)
    * Origin: The Kofo System II BBS telnet://fido2.kofobb
  • From Marc Haber@1:0/0 to All on Sun Oct 5 11:27:39 2014
    Joe The Smoe <news@edrusb.is-a-geek.org> wrote:
    Be careful about duplex setting when using a hub (always half duplex)!
    If you have forced full duplex on one (or more) host(s), collisions will >occur and will not be noticed by anyone,

    Until here, things are marginnally ok. People will of course notice
    abysmally bad performance.

    no retransmission will occur
    and packets that collided will be dropped silently because of at least a >wrong CRC.

    This is bullshit. TCP will notice packet loss and retransmit. UDP
    won't.

    Greetings
    Marc
    --=20
    -------------------------------------- !! No courtesy copies, please !! =
    -----
    Marc Haber | " Questions are the | Mailadresse im =
    Header
    Mannheim, Germany | Beginning of Wisdom " | =
    http://www.zugschlus.de/
    Nordisch by Nature | Lt. Worf, TNG "Rightful Heir" | Fon: *49 621 =
    72739834

    --- MBSE BBS v1.0.4 (GNU/Linux-i386)
    * Origin: private site, see http://www.zugschlus.de/ f
  • From Joe The Smoe@110:110/2002 to All on Sun Oct 5 19:07:58 2014
    On 05/10/2014 13:27, Marc Haber wrote:
    Joe The Smoe <news@edrusb.is-a-geek.org> wrote:
    Be careful about duplex setting when using a hub (always half duplex)!
    If you have forced full duplex on one (or more) host(s), collisions will
    occur and will not be noticed by anyone,

    Until here, things are marginnally ok. People will of course notice
    abysmally bad performance.

    no retransmission will occur
    and packets that collided will be dropped silently because of at least a
    wrong CRC.

    This is bullshit.

    not that much,


    TCP will notice packet loss and retransmit. UDP
    won't.

    a hub does not work at layer 4 like TCP or UDP does. I didn't assume
    anything about layer 3 (IP, IPX, OSI, etc.) nor upper layers... So let
    me be clearer:

    If two hosts forced in full duplex are connected to a hub, and send each
    an Ethernet Frame at the same time, none of them will be able to read
    the frame sent by the other host (layer 2 CRC error, runt, alignment
    error, etc.) nor they will be able to notice that their own frame
    collided. So the frames are lost, both.

    If they were in half duplex, they would neither be able to read the
    other host's frame, but would have seen the collision and would have retransmitted their own frame after an exponential backoff time. This
    has nothing related to TCP, we stay at layer 2 here.

    Of course if at layer 4 TCP is used, the lost frame will be noticed. And
    if UDP is used, the packet loss may also be noticed depending on the application used on top (TFTP for example will handle such packet loss,
    NTP also while it does not care/need retransmission, but can suffer some
    packet loss).

    The difference is the time it will take for a packet loss to be
    retransmitted. At layer 2 this is a matter of milliseconds while at
    layer 4 (TCP for example) this is a matter of seconds.

    The consequences for the user is the impression of a very slow or quite unusable network.


    Greetings
    Marc

    --- MBSE BBS v1.0.4 (GNU/Linux-i386)
    * Origin: Guest of ProXad - France (110:110/2002@linuxnet)
  • From Todd@110:110/2002 to All on Sun Oct 5 20:32:25 2014
    On 10/04/2014 03:41 PM, Todd wrote:
    On 10/03/2014 07:20 PM, Todd wrote:
    Hi All,

    I need to do some network monitoring with Wireshark.
    (modbus/tcp).

    I need an old fashioned hub (not a switch) to
    put between an appliance and a pump so I can see
    what is actually happening.

    Problem: all I can find are switches. Those
    don't work with Wireshark.

    Anyone know of a real hub out there. Only need three
    ports, but am not picky about more than that.

    Prefer 100 Base-T, but can live with 10-base-T

    Many thanks,
    -T

    Found on in my junk box. yippee!


    "on" should be "one"

    --
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    the riddle wrapped in an enigma wrapped
    in a couple slices of baloney
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    --- MBSE BBS v1.0.4 (GNU/Linux-i386)
    * Origin: A noiseless patient Spider (110:110/2002@linuxnet)
  • From Marc Haber@1:0/0 to All on Mon Oct 6 08:13:29 2014
    Joe The Smoe <news@edrusb.is-a-geek.org> wrote:
    If two hosts forced in full duplex are connected to a hub, and send each
    an Ethernet Frame at the same time, none of them will be able to read
    the frame sent by the other host (layer 2 CRC error, runt, alignment
    error, etc.) nor they will be able to notice that their own frame
    collided. So the frames are lost, both.

    Yes. Full Duplex basically means that collection detection is turned
    off. This - on a xBaseT-Link which has separate wires for transmit and
    receive - works only if there are only two devices on the link. Hence,
    a switch.

    Of course if at layer 4 TCP is used, the lost frame will be noticed. And
    if UDP is used, the packet loss may also be noticed depending on the >application used on top (TFTP for example will handle such packet loss,
    NTP also while it does not care/need retransmission, but can suffer some >packet loss).

    And both TCP or UDP based streaming services will be dead in the
    water, with UDP handling the situation much better.

    This is the practical result. Users usually don't care about ethernet
    frames, they care about IP packets, TCP streams and UDP datagrams.

    The difference is the time it will take for a packet loss to be >retransmitted. At layer 2 this is a matter of milliseconds while at
    layer 4 (TCP for example) this is a matter of seconds.

    Agreed.

    The consequences for the user is the impression of a very slow or quite >unusable network.

    Agreed. This has become more critical in times of IP telephony.

    Greetings
    Marc
    --=20
    -------------------------------------- !! No courtesy copies, please !! =
    -----
    Marc Haber | " Questions are the | Mailadresse im =
    Header
    Mannheim, Germany | Beginning of Wisdom " | =
    http://www.zugschlus.de/
    Nordisch by Nature | Lt. Worf, TNG "Rightful Heir" | Fon: *49 621 =
    72739834

    --- MBSE BBS v1.0.4 (GNU/Linux-i386)
    * Origin: private site, see http://www.zugschlus.de/ f
  • From Kirk_Von_Rockstein@1:0/0 to All on Tue Oct 7 14:48:34 2014
    On 2014-10-04, Todd <Todd@invalid.invalid> wrote:
    Hi All,

    I need to do some network monitoring with Wireshark.
    (modbus/tcp).

    I need an old fashioned hub (not a switch) to
    put between an appliance and a pump so I can see
    what is actually happening.

    Problem: all I can find are switches. Those
    don't work with Wireshark.

    Anyone know of a real hub out there. Only need three
    ports, but am not picky about more than that.

    Prefer 100 Base-T, but can live with 10-base-T

    Many thanks,
    -T

    Posting this for reference should someone search for similar
    in the future.

    Hub Reference
    http://wiki.wireshark.org/HubReference

    List of Switches with port mirroring http://www.miarec.com/knowledge/switches-port-mirroring http://wiki.wireshark.org/SwitchReference

    Tap Reference
    http://wiki.wireshark.org/TapReference

    More Good Info
    http://wiki.wireshark.org/FrontPage

    --- MBSE BBS v1.0.4 (GNU/Linux-i386)
    * Origin: The Kofo System II BBS telnet://fido2.kofobb