Keep one of these keys pressed at system start.

	Eject the inserted CD/DVD
	Boots from a CD/DVD with a system image
	Boots from the first HD partition
	Boots from the network (netboot)
	Enforces a screen reset
	Boots in firewire target mode
	Boots in safe mode. Disables login items and less important kernel files
	Boots in verbose mode
	Boots in single-user mode. Goes directly into command-line

This article describes how to change the session TTL for a specific port. In this example it is telnet.

config system session-ttl
 set default 1800
 config port
 edit 23
  set protocol 6
  set timeout 3600
  set start-port 23
  set end-port 23
 next
end

The session timeout is in seconds.

Protocol 6 is TCP.

Protocol 17 is UDP.

If you leave the protocol on 0, it is valid for all protocols.

Alternatively you can change the TTL per policy. Again, this is only possible on the command line.

config firewall policy
  edit 1
    set session-ttl 1800
  next
end

Users coming from the UNIX side are used to a life without anti virus scanner. Microsoft users feel uncomfortable and naked, if they don’t have a virus scanner. This discrepancy always leeds to discussions about the need of an antivirus scanner on an Apple computer. If you ask the AV industrie, they say you need one. Of course, there is a lot of money to make in this market. Experience shows, today you do not really need one.

Currently there are three known trojans for Mac available. One of them only installs, if you get a cracked verison of iWork 09. Even checking the signature list of an antivirus company only gives you a short list. Being a little bit careful from where you download your software helps more then spending a lot of money for software, which just slows down your machine.

Starting with 10.6 Apple started to scan downloads for trojans. There is a file called /System/Library/CoreServices/CoreTypes.bundle/Contents/Resources/XProtect.plist on your Mac containing the signatures of these three known trojans.

Anyway. Currently it is not necessary to spend a lot of money for virus protection on a Mac. If you want to scan your Mac from time to time, get the open source antivirus scanner clamav, with comes nicely packed with a nice frontend in a package called ClamXav. Download the free version and scan your Mac from time to time.

If you want to test your Antivirus Scanner, you can use the test string from the European Institute for Computer Antivirus Research  ”eicar“. Put this string into a file. Send it, download it, compress it, do what ever you want. Scan the file, see if your Antivirus scanner finds it.

Here the string.

X5O!P%@AP[4\PZX54(P^)7CC)7}$EICAR-STANDARD-ANTIVIRUS-TEST-FILE!$H+H*

Even if your scanner finds this pattern, keep your scanner updated. It is like in real life. The dangerous ones are the unknown ones.

The links in the table blow contain the test string. The files are compressed with different methods.

Safari 4 automatically stores previews from the sites you vist. If you do not like this feature and want to turn it off, do:

Open a Terminal and enter

defaults write com.apple.Safari DebugSnapshotsUpdatePolicy -int 2
rm "Library/Caches/com.apple.Safari/Webpage Previews/*"

Quit Safari and relaunch it.

To turn it back on, do:

defaults write com.apple.Safari DebugSnapshotsUpdatePolicy