Address Space Layout Randomization is an exploit mitigation technique which randomizes the process’ memory space in order to prevent the attacker from finding the addresses of functions or peripherals. One require the address of these to exploit them successfully.
Now coming to Linux, ASLR is available in Linux from kernel 2.6.12 and is forced on every executable.
Linux ASLR can be configured through
/proc/sys/kernel/randomize_va_space. Supported values are -
0 – No randomization.
1 – Only Shared libraries, stack, mmap(), VDSO and heap are randomized.
2 – Full randomization. Addition to point 1 memory managed through brk() is also randomized.