Sometimes you’re working in a network that has multiple external IP’s that are multiplexed. So for Typo3 your IP seems to change with nearly every click. With the default configuration you’ll be kicked out every now and then. To get rid of this problem, you can add the following snipped to your /typo3conf/lLocalConfiguration.php or /typo3conf/AdditionalConfiguration.php:
$TYPO3_CONF_VARS["BE"]["lockIP"] = 3 //1,2,3 or 4
The value determines how many blocks of your IP will be checked.
The following example shows which parts of your IP (f.e. 87.9.87) will be checked:
4 => 87.9.87
3 => 87.9.87
2 => 87.9.87
1 => 87.9.87