fix 32-bit application default 2GB limitation

ref: http://www.jvadillo.com/software/3gbproblem.html

http://www.dansdata.com/askdan00015.htm

Improving Windows XP memory management for large amounts of data

As mentioned in the Microsoft Help & Support page, there is a boot option called /3GB that reduces the amount of memory reseved to the system to the last 1GB, leaving 3 GB for user applications instead of 2GB.

Two actions have to be taken in order to have an application that can access more than 2GB of RAM:

1. Change your Windows XP boot.ini file to have the /3GB flag active. To do so open the C:\boot.ini file in a text editor:

[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Professional 3GB " /fastdetect /3GB

2. Change your executable application header activating the LARGEADDRESSAWARE flag.

This flag can be activated using a Visual Studio application called EDITBIN.EXE.To do so, just call the tool as follows:

editbin /LARGEADDRESSAWARE name_of_the_executable.exe

This action modifies the following fields of the PE header structure:

• IMAGE_FILE_HEADER.Characteristics: IMAGE_FILE_LARGE_ADDRESS_AWARE bit (0x0020) set.
• IMAGE_OPTIONAL_HEADER32 CheckSum is recomputed taking into account the modified field.

SFTP jail

summary:

In /etc/ssh/sshd_config :

You need to configure OpenSSH to use its internal SFTP subsystem.

Subsystem sftp internal-sftp

Then, I configured chroot()ing in a match rule.

Match User ftpuser
         ChrootDirectory /var/www/html
         X11Forwarding no
         AllowTcpForwarding no
         ForceCommand internal-sftp

create user

useradd ftpuser -g apache

chown root:root /var/www/html

usermod -d / ftpuser

detail : http://www.debian-administration.org/articles/590