After upgrading from 10.5.8 to 10.6.1 on my MacBook Pro, I was unable to connect to wireless networks unless I had already connected to them running under 10.5.8. Snow Leopard would "see" the new networks, but could not connect to them.
The Genius Bar at the Apple Store helped me solve the problem. We opened Library » Preferences » SystemConfiguration, and trashed the entire contents of that folder. We also deleted all locations in System Preferences » Network, and recreated the location Automatic. Finally, we rebooted.
So far, I have been able to connect to all wireless networks that I want to using OS X 10.6.1.
I have to manage several Macs in a lot of locations and I was very confortable with the Bonjour discovery, saved connections, and hidden features of the 10.5 Screen Sharing app. Alas, with the release of 10.6, they have gone -- Apple wants to sell Apple Remote Desktop.
I have found that using this command in Terminal...
defaults write com.apple.ScreenSharing controlObserveQuality n
...changes the quality of the connection's display, based on the value of n:
1 = black and white
2 = grayscale
3 = 8-bit color
4 = 16-bit color
5 = full color
I also set up shortcuts using the vnc://192.168.0.1 URL convention in Safari, as discussed in this hint and comments. I save all my connection shortcuts in a folder, and put that folder in my Dock. I now have a Saved Connections folder that I can use to launch Screen Sharing automatically.
[robg adds: This Terminal command was covered in this comment, but I felt it worth repeating as a full hint. If you have a Screen Sharing session currently open, you'll need to close and reopen it to see the changes.]
Whenever I delete a file from a network volume, I'm warned: 'The item "File name" will be deleted immediately. Are you sure you want to continue?' with Cancel or Delete as options. The Cancel button is always the default option. If you really want to delete the file, you need to use the mouse to select the non-default Delete button. Since I am always sure that I really want to delete this file, I'm a little annoyed by always having to use the mouse after typing Command-Backspace (the Move to Trash shortcut). After all, I am using a shortcut because I want to avoid using the mouse.
If you press Command-Option-Delete, however, the networked file will be deleted immediately, without any warning at all. As with the normal method of deleting a networked file, this deletes the file immediately.
[robg adds: You can avoid the mouse with the Command-Delete method by pressing Tab then Space after the dialog appears. If you look at the File menu with the Option key down, you'll see that the shortcut for Move to Trash changes to reflect the Option key's presence, but the description itself doesn't change. This works in both 10.5 and 10.6.]
For one reason or another, I have two wireless networks available to me to use in one location. One is DHCP enabled, while the other requires manual setup.
The obvious solution for switching between these networks is to use the Locations feature in Networking to save two profiles, and then use the drop-down Location menu to switch between them. However, I have found that because my MacBook has the logins for both networks saved, it does not switch the wireless network, just the settings. Once you mix DHCP with manual settings, it just fails to work, and requires more intervention.
My solution (admittedly inelegant, but I don't know how to implement a better way), was to create a shell script that will switch the locations, and power cycle the AirPort card (which means it picks up the 'preferred' network). This is then set as a Service using Automator, and assigned a keyboard shortcut. I have also had to configure sudo to allow my user to run it without a password.
This is not really Mac-specific, but still a good idea. I like two things: sharing and encryption. But you can't have both with wi-fi. Either you share it or you encrypt the OTA transmissions with WPA.
My compromise, which works for anyone in an apartment building is simple. Name your network like this:
Bring beer to [apt number] for Password
It's a nice way to get to know your neighbors, gets you free beer (pro tip: you can substitute other items for beer), and lets you be generous with your wi-fi while giving you some added level of security from the WPA encryption.
[robg adds: I can think of both upsides and downsides to this idea; it will be interesting to read what others think of it.]
If you previously used the Cisco VPN Client and want to use the native Snow Leopard client, you need to un-install all of the Cisco configs, kernel extensions, etc. To do this, just run sudo /usr/local/bin/vpn_uninstall in Terminal.
If you don't, the menu bar VPN control won't work, and will be very sluggish to click around in. The same goes for the Verizon Access Manager and the CDMA 3G built-in drivers.
I'm not sure if it's well-known, but Screen Sharing in Snow Leopard now supports all keyboard commands, including Command-Tab, Command-Space, and Command-Option-Escape. In 10.5, these keystrokes were sent to the local machine; in 10.6, they go to the screen sharing session.
[robg adds: In 10.6, whether you're sharing the screen of a 10.5 or 10.6 Mac, basically all keystrokes are sent to the remote machine, including kyes for Exposť and Dashboard -- if you've programmed separate keys beyond the hardwired keys -- F9 for Exposť's All Windows mode, for instance, gets sent from my MBP to my Mac Pro, but F3 (the hardwired Exposť key) does not. To send the keys locally, you'll need to click on a visible window (or the Desktop) behind the Screen Sharing session.]
Mac OS X Snow Leopard adds support for Cisco IPSec VPN connections -- that is, plain IPSec with XAuth authentication and mode_cfg.
That makes it two layers of authentication: first, Machine Authentication with a password (Shared Secret) or an X509 certificate. Then a traditional username-password pair for XAuth, both of which you can enter and save in the Account Name and Password fields respectively when you set up the connection. Trouble is, even though you entered your password and it is apparently saved in the keychain properly, Mac OS X keeps nagging you to manually enter the password every time you connect. Turns out this is a just bug with a simple fix.
Open the Keychain Access Application, select the System keychain and find your saved XAuth password entry in the list. Its Kind field will say IPSec XAuth Password. Open it, then on the Access Control tab click the Plus button to add another application. The file we need to select, /usr/libexec/configd, resides in a hidden folder. To navigate there, press Command-Shift-G, enter /usr/libexec, then pick configd in the dialog. Save your changes and that's it -- your saved password should now work.
[robg adds: I can confirm that this fix works as described.]