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 ...
Wednesday, September 5, 2012
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.
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...
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...
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...
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...
Redhat / CentOS Iptables Firewall Configuration
H
ow do I configure a
host-based firewall called Netfilter (iptables) under CentOS / RHEL / Fedora /
Redhat Enterprise Linux?
Icon reference for Firewall
Netfilter is a host-based firewall for Linux
operating systems. It is included as part of the Linux distribution and it is
activated...
What is sysctl.conf in Linux
sysctl is an interface that allows you to make
changes to a running Linux kernel. With /etc/sysctl.conf you can configure
various Linux networking and system settings such as:
1.
Limit network-transmitted configuration for IPv4
2.
Limit network-transmitted configuration for IPv6
3.
Turn on execshield protection
4.
Prevent...
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