Linux Iptables: Add / Delete An IP Address Remotely Using A Shell Script

Posted on in Categories , , , , , , , , last updated October 22, 2009

I’ve root ssh access and need to add / delete a few IP address on fly using the IPtables command via local shell script. How do I add or delete an IP address remotely over the SSH session under CentOS / Redhat / RHEL / Debian / Ubuntu Linux?

Linux Tuning The VM (memory) Subsystem

Posted on in Categories , , , , , , , , last updated October 16, 2009

I‘ve fast RAID-10 disk subsystem with multiple SCSI disks. Apps running under modern Linux kernel don’t write directly to the disk. They write it to the file system cache which is managed by Linux kernel virtual memory manager. Since I’ve high performance RAID controller I need to decrease the number of flushes. How do I tune virtual memory subsystem under Linux operating systems for better performance?

Linux Find Out CPU Support 36-bit Physical Addressing Or Not

Posted on in Categories , , , , , , , , last updated November 23, 2008

Q. Physical Address Extension (PAE) refers to a feature of x86 and x86-64 processors that allows more than 4G bytes of physical memory to be used in 32-bit systems. The x86 architecture presently uses only 36 bits out of 52 bits possible. On x86-64 processors, PAE is obligatory in native long mode; currently 40 bits are used out of 52 bits possible. How do I find out if my Linux kernel supports 36-bit or more physical addressing?