Firewall vs screen sharing

Hi,
since a few days, I'm using Lion on my iMac 24" (2008) and my MacBook Air (2010).
But now, I've some problems: Screen sharing from MBA to the iMac doesn't work if the firewall if the iMac is active.
Screen sharing from iMac to MBA: no problems. Strange?!
My router is a Time Capsule 3rd Generation.
Any idea how to solve this?
Thanks
Michael

Solved:
Iv've had to reboot my iMac and to configure the settings once again.
Then, the missing programms have been added to the firewall!

Similar Messages

Screen Sharing and Wake from Sleep

Hi,
I'd like to know if there's any way a Screen Sharing request from a remote vnc client can wake a Leopard machine from sleep. I've opened the vnc port on firewall, tested screen sharing while its awake... all good. When the target machine is asleep though it doesn't see the request as "Wake for Ethernet Administrator Access" I guess ?
Has anybody found a way to do this? I spoke to Apple support but they suggested I try Discussions.
Cheers.

None of the file sharing or screen sharing apps actually send the WOL packet. You can have launchd watch the screen sharing app and then send the WOL signal when you use it. There will be a slight delay but it does work. You need to download and install wol as it does not ship with osx. You will also probably want to get "lingon" so you can set up launchd easily.
Commentary: I find it ridicules that this stuff isn't already built into the apps. Electric costs money and using it unnecessarily is a waste. Yet not one of the apps or tools designed to work over ethernet with another computer sends the wol command. Its like the developers expect you to have your computer on 24/7.

Screen Sharing using Back to my Mac

I'm trying to use screen sharing for the first time between my 27" mid 2010 iMac and 15" MacBook Pro Retina late 2013 using both OSX 10.9.4 on a local network using Back to my Mac feature. I enabled screen sharing and made sure Remote Management is disabled and also on firewall the screen sharing has allow incoming connections enabled. I also have my Back to my Mac checked on my iCloud settings.
And so I opened Finder window on both computers and on the sidebars from each of the computers it showed the shared devices. So from my Macbook or iMac, I click on the device and then click on the share screen button and a menu popup asking me how i want to connect either as a registered user or using an Apple ID. I selected using and apple ID and it automatically provide a drop down showing my apple id and I click connect but all I get is an error message saying "Authentication failed to iMac" or vice versa.
What am I doing wrong? Is there any other option for me to do screen sharing without using a third party app? Please advise. Any help or suggestions will be greatly appreciated. Thank you.

Thanks for your input. At home, I use a Time Capsule, with the absolute latest firmware, so it should be suitable.
However, I might have problems with the setup? If I turn off and on Back to my Mac under iCloud settings, sometimes I get a message that I should enable NAT/UnPP. Checking the setup of the Time Capsule, the router is in Bridge mode (NAT off). If I try turning on NAT, I get an error in Airport Utility about double NAT.
Any advice on this?

Firewall says it allows screen sharing, but it doesn't

I've used screen sharing for years on this machine, but somewhere along the line, possibly in connection with the 10.7.5 update, I stopped being able to share its screen from other machines. Checking the system console, I see that the firewall is blocking screen sharing requests, and if I turn off the firewall screen sharing works. However, the firewall preferences panel says it is set to allow incoming screen sharing connections, so it should work. Symptoms are exactly the same if I switch on Remote Management instead of Screen Sharing. What am I missing? Note that this is an older Mac Pro that cannot be upgraded past Lion (sigh). Thanks for any advice.

http://kb.mozillazine.org/New_messages_do_not_appear

Screen Sharing and Virtual Desktop

Is there a way to force a new remote screen sharing connect to a "Virtual Desktop"?
In my experience, if another user is logged into the computer the new remote screen connection will be forced or given the option to connect to a virtual desktop. This will allow the new connection to run in the "background" without the first connection being influenced.
The issue is when a new remote connection is initiatied and no other connections are active the new connection will be shown on the computer's hardware monitor. i.e. No option is given to connect via a virtual desktop.
This is a security issue because a user can connect remotely and if he is the only connection on the computer he will have all his work shown on the hardware display.
I am hoping to find a way to force all remote connections to be on virtual desktops.

I guess its worth mentioning that although you can indeed screen share from Leopard to Tiger, it only works when you are on the same network. But Remote Desktop works across the internet...
Of course the trick to using Remote Desktop from a truly "remote" location elsewhere on the internet is that you have to be able to reach the IP of the computer you want to control, which can be tricky if its behind a NAT and the person your trying to reach is my Mom who has no idea how to configure her NAT, or firewall, or even find her IP address without my help.
Screen sharing Leopard to Leopard via iChat should be much more straight forward... translation: this will make my life much easier the next time my mom needs help.

Screen Sharing and Talktalk UK

Apologies if this duplicates what others have said. I've spent a lot of time trawling through here but I'm wondering particularly if the problem I'm having might be related to talktalk, my dad's provider.
1. I have an intel iMac running leopard. Comcast is my provider.
2. I can screen share both ways with my father in law in Rochester NY. He's on Roadrunner and has a G5 tower running leopard.
3. My Dad is in the UK with a split new macbook running leopard. He's on talktalk. I can share my screen with him but HE CANNOT SHARE WITH ME. When we attempt to do this, "screen sharing with <me>" comes up on Dad's screen, and we both get the audio connection, but at my end the small window with "connecting" just hangs on the screen. Wheel goes around endlessly, etc.
Because I can connect both ways with my father in law, I am assuming the problem is at Dad's end (although I'm not sure). Here's what I've done:
1. Our quicktime streaming speed is set at both ends at 1.5 Mbps, although I've tried the default too.
2. Bandwidth is 500k at both ends, although we've also tried none.
3. Firewall -- We both added ichat as a specific app and this actually made things worse -- when I tried to screen share a "failure" message came up on screen, and we couldn't video chat either. We both then reset the firewall to Allow all and at least then we could video chat.
4. UPnP is on at both ends.
The only thing I haven't tried at his end is the stuff I've read on here about Anonymous Pings, but it's really hard to do this when dad doesn't really know computers and when I don't know what the Huawei (this is his router) menu looks like.
Dad also has an Apple airport router which he as yet has not connected up. I'm wondering if he installs this between the Huawei and the ibook things might improve (I'm hoping against hope, really!).
Any suggestions, folks? Any ideas gratefully received.
Thanks,
Dr D

My guess is that your problem is not with your set-up but with TalkTalk. In my experience talking to my parents, who are also on TalkTalk, they tend to throttle their network for non-web traffic to the point where it's barely usable (if at all). For us, iChat usually exits the connection attempt with an "insufficient bandwidth" error message.
We have had more luck with Skype, but obviously that does not help with your screen-sharing question. Other than trying to change ISP, all I can think of is to try "calling" at less busy times.
Cheers,
--> Stephen

Screen sharing and ssh tunnel

I'm trying to connect screen sharing to a server (S2) on my local network through a server(S1) on my local network with a static IP (local) and a static IP (public)
S1 is XServer G5 10.3.9 (dual nic)
S2 is Mountain Lion Server 10.8.2
Client: MBP ML 10.8.2
Client -> S1 -> S2
IP are for illustration
S1: Public 71.100.100.200
S1: Local 192.168.6.100
S2: Local 192.168.6.101
S1 Firewall rule: 01105 allow tcp from any to 192.168.6.0/24 5900
On client:
> ssh -L 5901:192.168.6.101:5900 71.100.100.200
connect to server vnc://192.168.6.101:5901
... no joy connection timeout - standard connection fail message for screen sharing.

I managed to find a slightly different tunnel command that does work.
ssh -t -L localhost:5901:S2:5900 S1
ssh -t -L localhost:5901:<private server>:5900 <public(dmz) server>
had to set screen sharing prerferences for adaptive quailty encryption of passworkd and keystroks only for the relatively slow connection.

Screen sharing and file sharing not working on LAN

This is not a Mavericks specific problem since it existed before I upgraded to Mavericks. I have a LAN that consists of 3 MBPs and 1 MacPro.
Local screen sharing and file sharing works fine on all of these computers except for one MBP. From this MBP I am able to connect to all of the other computers for screen sharing and file sharing. But I can't connect to this particular MBP for screen sharing or file sharing from any of the other Macs.
This MBP shows up in the left hand side column under "Shared" on all the other computers. But I am unable to make a connection from any computer to the problematic MBP. I get the message, "There was a problem connecting to the server "xxxxxxxx". The server may not exist or is unavailable at this time".
I have tried toggling off and on screen sharing and file sharing with no effect. One probably pertinent strange thing that I notice is that under the Screen Sharing set up the green button next to "Screen Sharing:On" is green. But the message under it states:
"Other users can access your computer's screen
at vnc://johnmacbookproretina/ or by looking for “John MacBook Pro” in the Finder sidebar."
The problem is that my computer name is "John MacBook Pro" and the LocalHostName is "JohnMBPr.local". I believe that at some point in the past the computer name and/or LocalHostName was "johnmacbookproretina".
Similiarly, under File Sharing I am informed:
"Other users can access shared folders on this computer, and administrators all volumes, at “afp://johnmacbookproretina” or “smb://johnmacbookproretina”."
I would appreciate any help I could get to resolve this perplexing issue. Thanks.
John

I've finally been able to solve my own problem.
File sharing and screen sharing on the problematic MBP was being blocked by firewall rules that had been set up several weeks ago when I had installed a trial version of DoorStop X firewall software. I had previously trashed the app when the 30 day trial ended. I did not realize that the software had left a set of firewall rules in the Library/StartupItems folder. Among other things, the rules were set to deny access to the computer on the ports used for file sharing and screen sharing. Once I trashed the DoorStopStartup folder in the StartUpItems folder all the connection problems resolved with a computer restart.

Weird Screen Sharing problem/Finder

When using my MacBook Pro's Screen Sharing to view my Mac Mini, every Finder window shows as blank white in Icon View, but the files/folders show fine using List View, etc.
Both on OS X 10.9.1, both 2013 model computers.
Any ideas?

Using screen sharing at transcontinental distances is commonplace; there's no "other networks" setting here.
There's the IP network and firewall and ISP network configuration, and whether that (in aggregate) allows connections from elsewhere can connect to reach port 5900 (TCP) or whatever you're using.
And whether screen sharing is enabled on-LAN; via System Preferences on Client or via Server Admin on Mac OS X Server and punched through the applicable host-local and upstream firewalls, of course.
As for what IPsecuritas might be blocking or might be routing, you need ensure that passes port 5900 (TCP).

Can't access iTunes and Screen Sharing sharing services on my mac Mini

Since several weeks now I face a networking issue of the stranger kind.
Currently I've got my Mac mini acting as the central server for music, photos and files in my home. Central Network Mgmt device is a Wireless Lan router.
In the past I was accessing the Mac Mini from my MacBook via Screen Sharing this doesn't work anymore. When requesting the service the connection effort just runs idle. In iTunes on my MacBook I can see the Libary of my Mac Mini iTunes but clicking on it brings the rotateing ball and after a certain while the message that the iTunes Libary is not responding and that I should check my Firewall settings. Which I did on both computers and they are wide open. 'Ipfw show' in Terminal brings back the message 'Open for any to any communication' also on both computers.
Makeing use of the File sharing service from the MacBook to the MacMini works but it takes a extreme long while until the shared folder appears on the MacBook.
Trying to access from the Mac Mini my MacBook for all these services is no problem.
One more thing is that my Mac Mini cannot access the Wireless Lan router anymore thru the Web Browser or thru a Ping. Here I get the message 'Ping Send to: permission denied'. I changed the Router still the same message. Internet traffic is only possible after I manually applied a DNS Server with its IP number.
Anyone out there who could help? I'm close to completely reinstall my Mac Mini but would naturally love to avoid this.

wireduck,
Highlight the music folder and on the keyboard type (Command) + i: on the window that opens scroll down if need and click on the lock on the bottom right. Type in an Admin User name and password. Then under the (Sharing & Permissions:) make sure the users you want to open the folder are listed and that there (Privilege) is set to @ least Read. If not hit the ( + ) sign and add them. After you have that all set up click on the little gear next to the ( - )s sign and (Apply to a enclosed items). that way each user can read the files. After that the little ( - ) sign should be gone on the folders.
Hope that helps.

Screen sharing no longer works.

I cannot use screen sharing between my laptop and mini, although I used to be able to do so, after I "updated" to Lion. However, I can use file sharing, showing that wireless (airport) connection is working. This seems to be an Apple network problem. I tried the solutions posted (signing out of MobileMe, restarting my laptop), but Screen Sharing comes up, the "Connecting" window shows and then goes away, while the network/(my laptop name) window stays on. Laptop also shows up in the sidebar. Trying for Screen Sharing help gets me a message: "Topic currently unavailable." Is there a solution that does not involve connecting the two computers with an Ethernet cable?

Is Firewall turned off on both machines?

IChat screen sharing and video not working on MacBook but works on Mac pro

I have a MacBook and MacBook pro. Both have the lion os 10.7.2. I can use iChat on the MacBook pro for screen sharing, video chat, and text chatting, with others remote to me. However, I can only do texting with the MacBook. I can do screen sharing via Finder between my MacBook and MacBook pro. I can do FaceTime between both systems. I can also do FaceTime between the MacBook and anyone remotely.
I also tried installing teamviewer on the MacBook, and on a remote MacBook..... And I get the same results where I cannot share the screen, from the one that has not been working.
I have checked the settings under system preference and made sure screen sharing was enabled. I have checked under iChat under video to make sure screen sharing was checked.
The macbook that is having this problem is configured for AIM for iChat
I have run out of ideas. Any suggestions on what I might try?
Thanks

Ok,
I will list the ports in greater detail and point out when iChat uses them.
AIM Login and 1-1 Text Chatting
iChat version 1 through 5 will Log in to the AIM server on port 5190 (TCP Protocol) by default.
Since iChat 2 we have been posting here that the AIM servers allow a Login on almost any port and have been suggesting port 443.
This is used by both Web Browsers for secure Login to some sites and by the Mail app with some mail servers.
It is also below port 1024 (most domestic routers have the ports above this figure closed) In some campus situations using port 443 will normally allow at least Login and Text chatting.
iChat 6 uses port 443 by default.
File Transfers (AIM)
When doing File Transfers with AIM Buddies iChat will move to using Port 5190 on the UDP Protocol.
This cannot be changed. (This invokes the little Message about Starting Direct IM in an open Chat)
It also uses this port for Pics-in-chats, dropping Files on a Buddy's name with out a Chat or sending other files that are not pics.
In the case of Port Forwarding some devices don't like port 5190 being forwarded "twice" which is another reason for moving the login and Text chat port.
Jabber Logins
No matter what Jabber server you use ichat will use one of two ports (5222 and 5223)
Which one it uses is dependent on whether it needs and is using an SSL Login or not.
SSL Logins use port 5223 and NON SSL one use 5222 (ticking or Unticking the SSL box on a Jabber account will automatically change the port).
Google Talk is the exception in that it allow a Login on port 443 as well.
The First Apple Doc I linked you to says iChat uses port 5220 in Jabber.
I run Little Snitch and have never seen any version of iChat use this port at any time.
Bonjour
Any Mac to Mac Connection or Mac to any Bonjour able peripheral will be on port 5353.
This is normally opened (Preset) in the Mac Firewall for the Finder/System side of Sharing.
iChat needs and uses two other ports (5297 UDP and 5298 on both TCP and UDP)
As they an LAN Side connections the router would normally pass them.
At iChat 3 there were issues with the Mac Firewall (it included UDP set up and the preset in the firewall only listed them and TCP so we had people add all the iChat ports (you had to manually enter them in Tiger)
A/V Chats
No matter which Buddy List you start from iChat will do A/V chats the same way.
The Visible Invite you or your Buddy sends is on port 5678 (UDP)
In iChat 3 and earlier iChat then moves to port 5060 to send the SIP Connection Process invite behind the scenes (SIP = Session Initiation Protocol)
Port 5060 is one of 4 ports internationally agreed for SIP (How VoIP phones connect) (5060-5063).
Although ISPs were not supposed to block Through traffic many started blocking End users and then Charging them to open these ports (Many ISP were telecom companies that were losing long distant Telephone calls monies).
The SIP process then in iChat 3 contacts a server run by Apple for this purpose (Snatmap.mac.com to give it it's full name).
This acts like a old fashioned telephone operator connecting the call.
SIP is a text based process.
Your end "Calls" the operator.
The Operator "Calls" Buddy.
Buddy Accepts
iChat then negotiates the ports to be used.
In iChat 2 and 3 it uses 4 ports (vid in Vid out, Audio In and Audio Out) from "the group of 20" starting at the bottom (16384 to 16387 normally)
Three and 4 way chats uses more ports (which is why 20 are set aside)
In iChat 4 Apple realised the issue with the 5060 port and changed the way iChat worked
Since then it has Sent the invite on Port 5678 but then moved to port 16402 (it starts at the top of a smaller group of 20)
All Video and Audio traffic is also now on one port (so no need for 20 ports and iChat now lists 10).
NOTES so Far.
File Sharing during a Chat converts the Chat to Direct IM for AIM Logins
This is Peer-to-Peer in AIM
A/V Chats are Peer-To-Peer and you can actually log out of the Buddy list and continue the chat. (The exception is using iChat 6's AIM Video relay option)
Screen Sharing
Screen Sharing is an Audio Chat with a VNC connection along side.
Both bits have to wok to avoid the Pop-up to send to Apple and the Log that contains.
The Audio part is on port 16402 and the VNC part is random. (So random it is different every time you do it)
The reason it is classed as an Audio Chat+ is so the AppleScript for Auto Accept can filter out Screen Sharing connection and Not Auto Accept them.
This does have a knock on effect as far as your Router is concerned as already mentioned earlier.
You cannot Forward or Trigger the random Port so you have to use UPnP in your router to open the ports.
NOTES
Jabber File sharing may possibly be on port 1080 as listed in the Server Article I linked you to (I have also seen it written about in other stuff I have come across)
However Little Snitch does not seem to confirm this either.
Most time it will be peer-to-peer like the AIM connections for this.
However some Jabber servers do not seem to allow this and have this Jabber65 Proxy set up which passes things Server to Server in between it leaving your end and arriving at a Buddy.
This on Port 7777 but you do not need to open this port (unless you are running a Jabber server)
I have yet to test File Transfers using a Yahoo Buddy List in iChat 6.
AppleCare and Geniuses.
Previously I have been contacted by Geniuses in Stores asking to test customer's iChat.
They and the Applecare people have details about Apple wants an designed the App to work.
What they don't have is the knowledge about what it takes to set it up in the "real world".
There are literally thousands of Makes and Models of routers.
Some like the Thomson-Alcatel brand state they are SIP/VoIP ready but this means the router strips out all SIP Data trying to send it to a Phone.
Early models of Alcatels can get around this with a tweak. Later models can't.
Motorola devices tend not to have UPnP.
Apple Base Stations have Port Mapping Protocol instead of UPnP and this needs setting up.
The Zyxel range definitely does not like the dual use of port 5190 and does much better using UPnP (You almost certainly have to do your AIM login on port 443 with these).
1. I have two computers (MacPro and MacBook Pro) that are both running Lion 10.7.2 and both running iChat 6.0.1. <<-- Fine
2. The Netgear router model is: WNDR3700.    <<<<--- With any Brand there are exceptions and I do wonder about this one
3. The firewall for both Macs is turned on and in the advanced area iChat is listed as being "allowed." <<<<---- Fine
4. In iChat, under the video options, "Screen Sharing Allowed" is checked.                                        <<<<<---- Fine
5. In System Preferences, "Screen Sharing" is checked and this is for "All Users" at present.               <<<<<---- Not Required
6. There are two separate AIM accounts being used for iChat purposes.                                            <<<<<---- OK
7. In iChat preferences, each AIM account is "Enabled" under "Account Information" and the "Server Settings" show the Server as "api.oscar.aol.com" and the Port is "443" and "Use SSL" is checked.                                <<<<---- As it should be
From this and the other info in the first port it was only the router set up that seem to throw some light on a possible cause (Port Forwarding and UPnP conflict)
If just doing Port Forwarding the ports listed would have covered things (Except the Screen Sharing's random port)
Regarding your latest post.
I have table similar to that on my Sagem 2504Fast Modem/router combined device and it too seems to list a different port on the external side on occasions.
I would try the router with the Disable SIP ALG unticked (so it is not disabled). If the Help info on the right gives any info about what this Netgear version does it would be helpful.
Some are like the Thomson-Alcatels I was talking about in that it points the SIP data to a specific place (Possibly a Phone socket on the device)
Others seem to provide an "boost" to enable SIP to work and don't seem to get in the way of iChat.
Try adding the Names in Table 1 from this page and see if you can Video to those.
There are 6 names in total (I am actually only seeing one on Line as I type)
9:19 PM      Wednesday; January 25, 2012
Please, if posting Logs, do not post any Log info after the line "Binary Images for iChat"
 iMac 2.5Ghz 5i 2011 (Lion 10.7.2)
 G4/1GhzDual MDD (Leopard 10.5.8)
 MacBookPro 2Gb (Snow Leopard 10.6.8)
 Mac OS X (10.6.8),
"Limit the Logs to the Bits above Binary Images."  No, Seriously

Screen Sharing Not Working

I have screen sharing turned on and it works fine when I'm in the house in front of the computer on the same network, but when I'm at the office trying to share the screen it is not working. I'm I doing anything wrong?
I have the Macbook Pro hooked up to my TV (main monitor). I have the computer screen on "never sleep" (computer screen is damaged from motorcycle accident-can't damage any more) and the keyboard lights turns off after 5 seconds of none use.

I'm leaving my personal MacBook pro at the house and using my office MacBook Pro trying to share the screen. I'm using the assigned vnc://ipaddress to login. What I mean by not working is that I get a message stating that my computer cannot be found. I drive home from the office (I don't do anything to the house computer) and sit in my yard and screen sharing works.
Most likely when you are in your yard, you are connecting to your home WiFi network and this by definition is the same as being in the living room.
If I need to configure my home router to port forwarding I'm not sure I know what to do and how to do it.
Depends on the make and model of router. A Google search for "Port Forward yourroutermake yourroutermodel" will most likely find instructions.
I'm talking my Mom, who lives in Louisiana, into buying a Mac and I told her I could help in Arkansas by screen sharing. So, is Port Forwarding a default feature on most routers?
Yes, most routers allow Port Forwarding, however, for your Mom there are other options.
a) Get 2 Free AOL Instant Messaging (AIM) accounts. Give one to your Mom. Now use iChat and in Mac OS X 10.5 (Leopard) there is an iChat option where you can ask your Mother to share her screen or she can click a button to export her screen to you.
b) If your mother is not going to be around when you work on her Mac, you could install an iChat add-on called Chax which has an option to always accept requests for screen sharing. Your Mother would have to be very careful about who she allows in your iChat "Buddy List". This is also an option for your work vs home situation.
c) Skype has a Mac OS X beta version that includes Screen sharing. You could use this for your Mom. No home router issues.
d) You can subscribe to Apple's MobileMe service and use the Back-to-My-Mac feature. You must make both your systems and your Mom's Mac part of your account. Is not suppose to have home router issues, but Back-to-My-Mac works best with Airport Extreme or Express routers.
e) You can use LogMeIn.com for screen sharing. No home router issues. However, LogMeIn.com is not as fast. However, it is fairly reliable and easy to get setup.
f) You can Port Forward the screen sharing ports in your and your Mom's home router.
I would like to have control of the mac at home and my Mom's new mac. How screen sharing works when I am at the house is exactly what I need. I see the other MacBook Pro in a window on my MacBook Pro computer and I have full control of the Mac.
You can get full control, you just need to deal with your home router.
Also note: Depending on how your Work network is setup, you may nave to deal with corporate firewalls that may not be happy passing your screen sharing requests.
So do you have a corporate firewall? Do you have to configure a Proxy server in System Preferences -> Network -> Advanced -> Proxy? If you do, then you may have additional hurdles connecting from work to home.
However, going from your home to your Mom's Mac only needs to deal with Port Forwarding on your Mom's home router.

Ichat Screen Sharing will not work no matter what I try...

I have read all the forums and can't find an answer. Something that should be so simple such as screen sharing through iChat (as advertised) is virtually impossible. This I can not explain. Especially since video chat works!
Both computers in question here are macbooks, both have leopard, both are or wireless networks. Is the router blocking the connection and if so, why will it allow video chat but not screen sharing?
There is either something real simple that I am missing here, or this is not possible at all.
some things that i have tried:
disabling stealth mode
on the firewall, enabling incoming traffic from ichat
made sure screen sharing is enabled in ichat
made sure the settings were the same on the remote apple computer
tried unchecking everything in the sys pref "sharing"
Both of the parties involved are using the same ISP, this really is mind boggling.
Is this a bug that is being fixed or what? I am not trying to perform a miracle here, but this is getting ridiculous.
If this is a router issue, apple should release some documentation on how to configure ichat screen sharing through your router.
If anyone has had this problem and has a fix, I would love to hear it. Keep in mind I have googled this many times and tried just about every piece of advice that I could find on this.
Thanks

iChat Screen sharing does not as such for the screen bit use the Video/Audio port.
The Documentation was lacking last time I looked.
This one tells you the port changes in Leopard http://docs.info.apple.com/article.html?artnum=306688 compared to Tiger
Tiger is linked in the first to here http://docs.info.apple.com/article.html?artnum=93208 where most of the other ports are.
However Screen sharing was not part of iChat 3.
If you do a Quick Look at the .plist(s) you will see the reference to ARD which is Apple Remote Desktop which is what the screen ending part is based on.
This Doc will tell you which ports ARD is likely to use
http://docs.info.apple.com/article.html?artnum=106439
(It says 5900 and 5988)
This should be allowed through the use of UPnP in your routing device or specifically opened.
Now the not so good news.
I run Little Snitch, A utility that tells you ports and IPs of incoming and outgoing network connections by any app you have.
This has told me that in fact the Screen port seems almost completely random normally in the 50000 range of ports
It may not be all you wnat to hear but I hope it helps.
9:57 PM Tuesday; February 12, 2008

IChat screen sharing does not work on my Mac Pro

I have a weird iChat screen sharing problem that i can't seem to resolve on my Mac Pro. Ever since i got my Mac Pro in early 2008, using the screen sharing feature in iChat has always been flaky. I have never gotten to the point of getting it consistently working. Lately, i have not been able to get it to work at all.
Most of the time, when i choose to share my chat target's screen (or when i share my screen), i would be able to see my chat target's screen and use the mouse for several seconds before the shared screen session is ended. The errors that i am getting are:
+"Disconnected from Screen Sharing because:+
+No data has been received for the last 10 s..."+
+"There was a communication error during your chat.+
+No data has been received for the last 10 seconds. You can send+
+details about this problem to Apple to help improve future versions of+
iChat."
On other occasions (mostly when i am trying to troubleshoot this issue by testing in the same network with my Powerbook, which is on 10.5.6 as well), i get this error:
+"Disconnected from Screen Sharing because:+
+Screen sharing could not be established."+
I have tried to do screen sharing via iChat with other Macs in the same network and also on the internet but with the same problems.
Initially, i thought this may be router related. But the fact that iChat screen sharing on my Powerbook works perfectly both in intranet and internet eliminates my router as the culprit.
I have also tried disabling the OSX Firewall but the outcome was the same.
I read some posts that there may be issue with using the external iSight web cam. I unplugged it, cleaning up all the iChat-related caches and preferences and tried again but with the same result.
I have also tried connecting to iChat using several different account types (mobileme, .mac and AIM) but the end result is the same.
I run a Ubuntu VMWare fusion VM on my Mac Pro as my webserver. I thought that may be the problem. Shutting down the Ubuntu VM also does not help.
Applecare support personnel also instructed me to re-install iChat but that did not help as well.
One interesting error i noticed in the system.log (seen via the Console app) that is generated everytime iChat screen sharing fails on my Mac Pro:
+12/23/08 12:32:00 AM /Applications/iChat.app/Contents/MacOS/iChat[507] error getting server version+
I am really running out of ideas on what else i can do to get this resolved.
Thanks in advance for any suggestion.
Message was edited by: Changren Yong
The audio and video chat portions of iChat work fine.

I managed to make some headway in my attempts to troubleshoot this problem. I did a fresh Leopard install on one of the drives in my Mac Pro. I then proceeded to update it to 10.5.6. After that, i launched iChat and attempted screen sharing with my Powerbook. The first few attempts failed, with the following symptoms:
- i would be able to see and control the Powerbook's screen
- after 5 seconds, my screen sharing session is disconnected
I then unplugged my external iSight. After i relaunched iChat, i managed do screen sharing in iChat without being disconnected!!! When i connected the iSight back into the ACD, with iSight off, i attempted to screen share again. This time, it failed after about 5 seconds, just like earlier. I then turned iSight on. This time round, the screen sharing session was not disconnected!!
So in addition to the iSight issue, something in my original Leopard startup disk is causing iChat screen sharing to fail because even when screen sharing was failing on my fresh Leopard install, i do not see this error:
/Applications/iChat.app/Contents/MacOS/iChat(507) error getting server version
So if i can figure out what is causing this error to show up in system.log, then i can manage the iSight issue.

Firewall vs screen sharing

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