Why can't ichat, Mail and Skype connect to my ethernet cable?

Question

I recently moved to Ireland and my internet here is provided by my school, it works with my studentnumber and password. So filling in the proxy of my school, as my network,  i can connect to the internet using Safari, iTunes and firefox. I just had to give in my student ID and password. But when I turn on Mail, Skype or iChat, they can't connect to the internet because there's no connection.
The applications are working just fine but they just can't connect to the intenet.
Please help!

Answer 1

Hi,
Umm,  an interesting one.
iChat
iChat up to an including iChat 5 in Snow Leopard has never like Proxies.
In fact if you did you them it did better when the System Preferences > Network listed the Proxy rather than the iChat App itself.
One thing I would try is to go to iChat > Preferences > Accounts and for Any AIM Login go to the Server settings and change the port to 443 and try Logging in.
The AIM server accept logins on almost any port.
Port 443 is used by Web Browsers for Secure site and Mail can sometimes use this port for some mail servers so it is likely to be an open port in any routing device there is place between you and the internet proper.
Google Talk Logins will also accept changing the port to 443
Other Logins such as plain Jabber Names do not allow different ports to be used.
However thses changes may at least allow you to Text chat.
Skype.
if you go to the Preferences here it should list a port that the app would like to use.  (it tends to be different with different downloads)
Normally if it finds this port is not open in a router it uses Fall Back ports (Normally port 80 used for Web Browsing)
As it is not working it suggests the school are using some other method to prevent it.
Mail.
Mail uses a whole host pof different ports normally based on what type of service you have and who with.
It is fairly common though for outgoing mail to be on port 25.
Incomming mail may be on port 110, 565, 996, 995 and quite a few others
However all these are below the port 1024 threshold  (most routers have ports upto this point opne for things like Web Browsing and Mail although on more sofisticated routers even these can be blocked.
I have one email account based on an old Dial-up service.
I can acces the Incoming server to retrieve mail via my current ISP but I need to be logged in via Dial-Up to use the outgoing server (Although Mail sends it out on Port 25 their end blocks accepting it as it is not coming from the right place).
Something similar may be happening for you with Mail and the Proxy with the services you are using.
Things to do.
1) Post in the Lion area about using Proxies.
Someone there is likely to know much more than I do.
2) Talk to the School IT dept. about accessing email accounts using the Proxy.
They may not be deliberately blocking this but may not have given out the info needed.
3) They may be blocking Skype for "security" or Bandwidth issues or even to stop students "Wasting Time".
iChat doing a Video chat is very bandwidth intensive and may be blocked because of that (as well as students using it during class).
You may find the school is unwilling to compromise on any of this.
8:26 PM      Saturday; September 3, 2011
Please, if posting Logs, do not post any Log info after the line "Binary Images for iChat"
 G4/1GhzDual MDD (Leopard 10.5.8)
 MacBookPro 2Gb( 10.6.8)
 Mac OS X (10.6.8),
"Limit the Logs to the Bits above Binary Images."  No, Seriously