DaiVernon

Q: DHCP and iChat

We run a small apple network ( 40 desks) within a larger Windows environment. Corporate IT tolerate us (just!!) and give us network access. Our printers and Macs have fixed IP addresses *except* for a couple of rooms which apparently HAVE to run DHCP network ports. Not an issue to the occupants of the room, but irritates me that ARD is useless unless occupant advises me of current DHCP assigned IP address...iChat is flaky, too... Occupant seems to be permanently offline - maybe she is and is using the office PC - I cannot easily tell!! Want to use iChat as a messaging service, hoped it would seem more responsive than email, handy for leaving message when occupant on the phone etc...

 

Using WGM I've set ALL macs to open iChat at logon - doesn't seem to bring this room's occupants online...unless they're switching off iChat by choice!!??**

Mac mini, Mac OS X (10.6.8), Macbooks, MacBook Pros, iMacs

Posted on May 21, 2012 7:41 AM

Close

Q: DHCP and iChat

  • All replies
  • Helpful answers

  • by Ralph Johns (UK),

    Ralph Johns (UK) Ralph Johns (UK) May 21, 2012 12:42 PM in response to DaiVernon
    Level 9 (73,087 points)
    Applications
    May 21, 2012 12:42 PM in response to DaiVernon

    Hi,

     

    iChat Bonjour uses port 5353, the Standard Broadcast port for Bonjour on the Mac that shows other Macs in the Finder's Side bar under Shares (If Showing Shares Is ON)

    This uses the UDP Protocol.

     

    As this part is Zero Configuration it should not matter whether the computer is a DHCP Issued IP or not.

     

    This Zero Configuration will show the Computer name (As seen in System Preferences > Sharing) when in th FInder's Side Bar.

     

    In iChat the app takes this a stage further and grabs the Users ID from their Address Book and broadcasts that as their Buddy name in other people's Buddy Lists.

     

    The Apple Doc  (See Note 2) on the subject then says iChat uses ports 5297 and 5298 on the UDP Protocol and 5298 on TCP as well to send Text Chats and Files.

     

    NOTE

    The AIM  Login is by default on port 5190 on the TCP Protocol and Files are sent over AIM via the UDP but also on port 5190

     

    The Bonjour Set up seems to have been set up the Same way (Using one port Twice and different Protocols).

     

    I have run Little Snitch in the past but have never bothered to restrict the Local Stuff so I can see if iChat Bonjour does use all the ports Apple claim.

     

    It is only after this point, when you move into Audio and Video Chatting that having a set IP (NON DHCP or "DHCP with Manual IP" in the Network settings)  becomes more important.

     

    There is one important fact and that is the Bonjour Computers must all be on the same Subnet of the LAN and it sounds like they have their own Subnet.

     

    So...

    Check these computers show up in Shares in the Finder on the computers in that room.

    Check they show up on other computers not in that room.

    Compare the IP addresses in System Preferences > Network > Advanced Button > TCP/IP tab  (If you are using Ethernet you can see this info on the first "Screen" by Wifi will need the "Advanced Button" I list).

     

    NOTE

    Lets say the router  has an IP of 192.168.0.1  It will issue all DHCP IPs in the range 192.168.0.xxx  (Actually it will allow Static/Manually set IPs in the same range)

     

    If there is a second router it will get an IP from the first but have a different range that it Broadcasts, possibly 10.x.x.x but could look similar as in 192.168.1.x

     

    Computers in the 10.x.x.x or 192.168.1.x will be in a different subnet to computers in the original 192.168.0.x group.

     

    A Router can support itself and 255 other devices.

     

    After that it may be a question of double checking that the ports iChat Bonjour uses are actually allowed for Local traffic (It is rare that this sort of thing is Blocked)

     

     


    8:42 PM      Monday; May 21, 2012


    Please, if posting Logs, do not post any Log info after the line "Binary Images for iChat"

     

      iMac 2.5Ghz 5i 2011 (Lion 10.7.4)
     G4/1GhzDual MDD (Leopard 10.5.8)
     MacBookPro 2Gb (Snow Leopard 10.6.8)
     Mac OS X (10.7.4),

    "Limit the Logs to the Bits above Binary Images."  No, Seriously