Syscall Tracker is a very powerful tool for Linux 2.2 and 2.4 which allows you to write rules to track system calls. It includes a kernel module plus a userspace applications. Currently only logging the invocation is supported, but in the future, you will be able to fail the system call (i.e. force it to return some error code), or suspend the process executing it. Allows you find out info that is hard to find, for instance to determine which process touched a certain file.
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