********************************
#!/bin/bash
# Shell Script To
List All Top Hitting IP Address to your webserver.
# This may be
useful to catch spammers and scrappers.
# where to store
final report?
DEST=/var/www/reports/ips
Wednesday, September 5, 2012
Basic of Shell Script
What Is a Shell?
Ø The shell is a user
program or it is an environment provided for user interaction.
Ø It is a command language
interpreter that executes commands read from the standard input device such as
keyboard or from a file.
Ø The shell gets started
when you log in or open a console (terminal).
Ø Quick and dirty way to
execute utilities.
Ø The shell is not part of
system kernel, but uses the
system kernel to execute programs, create files etc.
Ø Several shells are
available for Linux including:
Ø BASH ( Bourne-Again
SHell ) - Most common shell in
Linux. It's Open Source.
Ø CSH (C SHell) - The C shell's syntax and
usage are very similar to the C programming language.
Ø KSH (Korn SHell) - Created by David Korn at AT
& T Bell
Ø TCSH - It is an enhanced but completely
compatible version of the Berkeley UNIX C shell (CSH).
Please note
that each shell does the same job, but each understands different command
syntax and provides different built-in functions. Under MS-DOS, the shell name is COMMAND.COM which is also used for the same
purpose, but it is by far not as powerful as our Linux Shells are!
Linux log files location and how do I view logs files?
Q. I am new to Linux and I would like to know
where are the log files located under Debian or Cento OS Linux server? How do I
open or view log files?
Ans. Almost all logfiles are located under /var/log directory (and subdirectory). You can change to this directory using cd command but you need to be the root user. You can use less, more, cat or tail command to see the logs.
Ans. Almost all logfiles are located under /var/log directory (and subdirectory). You can change to this directory using cd command but you need to be the root user. You can use less, more, cat or tail command to see the logs.
Go to /var/logs
directory:
How do I rotate log files?
Q. How do I rotate log files under Linux operating system?
A. You need use tool called logrotate, which is
designed to ease administration of systems that generate large numbers of log
files. It allows automatic rotation, compression, removal, and mailing of log
files.
Each
log file may be handled daily, weekly, monthly, or when it grows too large.
With this tool you keep logs longer with less disk space.
Default configuration file
The default configuration file is
/etc/logrotate.conf:
Redhat Enterprise Linux 5 / CentOS 5 monitor and track TCP connections on the network
Q. How do I track and monitor connection for eth1 public
network interface under Redhat Enterprise Linux (RHEL) 5 server?
Ans.You can use netstat
command or tcptrack command. Both command can show established TCP connection
and provides the ability to monitor the same.
BASIC LDAP CONFIGURATION For RHEL / Centos / Fedora
INTRO: LDAP stands for Lightweight Directory Access Protocol. It is used as
centralized data (or
Directory)
server (not database server)
for various purposes.
There
is a difference between Directory server
and a Database server.
In
Directory server
the data is read more frequently than it is
written.
In
Database server
the data is written more frequently than it is
read.
Here
we shall see how LDAP is
used for creating centralized users (Network
users).
The
Network Users can also be configured using NIS
SUPPORTIVE SERVICES:
Configuration
of NFS is
required at server and
client end.
NFS plays
the backbone for LDAP as it provides the Directory
throughout the network.
Without
NFS configuration
of LDAP does
not work.
Monday, September 3, 2012
Linux: Iptables Examples For New SysAdmins Part -->3
Before see this post please read my
previous post (Linux: Iptables Examples For New SysAdmins Part -->2)
#12: Log and Drop
Packets
Type the following to
log and block IP spoofing on public interface called eth1
# iptables -A INPUT -i eth1 -s 10.0.0.0/8 -j LOG --log-prefix "IP_SPOOF A: # iptables -A INPUT -i eth1 -s 10.0.0.0/8 -j DROP
Linux: Iptables Examples For New SysAdmins Part -->2
Before see this post please read my previous post (Linux: Iptables Examples For New SysAdmins Part -->1)
#3: Delete Firewall Rules
To display line number
along with other information for existing rules, enter:
# iptables -L INPUT -n --line-numbers
# iptables -L OUTPUT -n --line-numbers
# iptables -L OUTPUT -n --line-numbers | less
# iptables -L OUTPUT -n --line-numbers | grep 192.0.43.10
Linux: Iptables Examples For New SysAdmins Part -->1
Linux comes with a host based firewall called
Netfilter. According to the official project site:
netfilter is a set of hooks inside the Linux
kernel that allows kernel modules to register callback functions with the
network stack. A registered callback function is then called back for every
packet that traverses the respective hook within the network stack.
This
Linux based firewall is controlled by the program called iptables to handles
filtering for IPv4, and ip6tables handles filtering for IPv6. I strongly
recommend that you first read our quick tutorial thatexplains how to configure a host-based firewall called Netfilter (iptables) under CentOS / RHEL / Fedora /
Redhat Enterprise Linux. This post list most common iptables solutions required
by a new Linux user to secure his or her Linux operating system from intruders.
Redhat / CentOS Iptables Firewall Configuration
H
|
ow do I configure a
host-based firewall called Netfilter (iptables) under CentOS / RHEL / Fedora /
Redhat Enterprise Linux?
Netfilter is a host-based firewall for Linux
operating systems. It is included as part of the Linux distribution and it is
activated by default. This firewall is controlled by the program called
iptables. Netfilter filtering take place at the kernel level, before a program
can even process the data from the network packet.
|
| Icon reference for Firewall |
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