How to enable IPTABLES support in Linux Kernel
You need to recompile kernel to enable IPTABLES support.
Get into the kernel source directory:
# cd /usr/local/src/kernel [download kernel source from kernel.org]
# Copy your current running kernel config.
# make menuconfig
Networking >> Networking options >> Network packet filtering (replaces ipchains) >> IP: Net Filter configurationS >> IP Tables support
# make
# make modules
# make modules_install
# make install
Move to /boot/grub and then modify your current grub config to load the new kernel.
Tags: iptables, Linux Kernel
Reinstall Grub Boot Loader
GRUB is a boot loader package from the GNU Project. GRUB is the reference implementation of the Multiboot Specification, which allows a user to have several different operating systems on their computer at once, and to choose which one to run when the computer starts.
You can re-install grub by linux rescue method:
1) Put the 1st bootable linux cd on cdrom.
2) Reboot the system.
3) At boot prompt type “linux rescue” without quotes.
4) You will get a shell prompt.
5) Give command chroot /mnt/sysimage
6) Run: grub-install /dev/hda (primary master)
7) Reboot the system
Tags: Grub Boot Loader
How to mount a linux LVM volume
You can check the disk that is using the LVM volume by using the command fdisk -l
You can run the command “pvs” to get the volume group.
You can run lvdisplay /dev/”volume group”
This will display the list of logical volumes in the volume group
#lvdisplay /dev/VolGroup00
The volume group here is VolGroup00
# Mount the partition
mount /dev/VolGroup00/LogVol00 /home
The Logical volume here is LogVol00
Tags: LVM, Mount
Network Address Translation
PREROUTING
Address translation occurs before routing.
Facilitates the transformation of the destination IP address to be compatible with the firewall’s routing table.
Used with NAT of the destination IP address, also known as destination NAT or DNAT.
POSTROUTING
Address translation occurs after routing.
This implies that there was no need to modify the destination IP address of the packet as in pre-routing. Used with NAT of the source IP address using either one-to-one or many-to-oneNAT. This is known as source NAT, or SNAT.
Tags: NAT
Yum Commands
YUM packages updater (Fedora, RedHat and alike)
Download and install a rpm package
This will install an RPM, and try to resolve all the dependencies for you using your repositories.
yum localinstall package_name.rpm
Update all rpm packages installed on the system
Upgrade a rpm package
Remove a rpm package
List all packages installed on the system
Find a package on rpm repository
Clean up rpm cache erasing downloaded packages
Remove all files headers that the system uses to resolve dependency
Remove from the cache packages and headers files
Tags: packages updater, yum
