Turning off ping responses in RHEL5

There are so many processes to block ICMP ping in RHEL5. This process is about “How to block ICMP packets through Kernel Configuration?”

Persistent system configuration : sysctl -a (Lists all current kernel settings)
Settings a /proc value dynamically : sysctl –w (Kernel settings)
Reloading Kernel settings : sysctl –p

To block ICMP packets : /proc/sys/net/ipv4/icmp_echo_ignore_all
: Search for sysctl –a grep net।ipv4।icmp_echo_ignore_all

set the value
Sysctl –w net.ipv4.icmp_echo_ignore_all=1

Ping “IPAddress”
PING 192.168.x.x (192.168.x.x) 56(84) bytes of data.
No response...

Sysctl –w net.ipv4.icmp_echo_ignore_all=0

PING 192.168.x.x (192.168.x.x) 56(84) bytes of data.
64 bytes from 192.168.x.x: icmp_seq=1 ttl=64 time=0.889 ms

--- 192.168.x.x ping statistics ---
5 packets transmitted, 5 received, 0% packet loss, time 4002ms
rtt min/avg/max/mdev = 0.079/0.261/0.889/0.315 ms

If you want to make this persistent across reboots..!

Edit /etc/sysctl.conf
Search for net.ipv4.icmp_echo_ignore_all
Change the value to 1 or 0 as per your requirement.
Update your system kernel settings : Sysctl –p
Shutdown –r now

Ping “IPAddress”
PING 192.168.x.x (192.168.x.x) 56(84) bytes of data.
No response ...

Creating a Private Repository In RHEL5 and installing Packages with yum

To create a private repositroy in RHEL5 the following package should be installed in your system.

Createrepo *.rpm file - To know the package is installed in your system or not ?
rpm –qa grep createrepo* (or) rpm-q createrepo
To install it : rpm –ivh createrepo*।rpm

rpm –qa grep yum* (or) rpm-q yum
To install it : rpm –ivh yum*.rpm (All Packages)


Run command createrepo –v /package/RPMS
(Put all your packages in /var/www/html/(Create Directory for RPM packages) and start your http server by executing the command service httpd start or chkconfig –level 12345 httpd on
Or
Put all your packages in var/ftp/pub/RPMS and start your ftp server with service vsftpd start or chkconfig –level 35 vsftpd on)

Ex:- createrepo –v /var/www/html/RPMS
Do http://localhost/RPMS/ (firefox)

You have created a repoistory.

Configuring yum package manager

Create a file in /etc/yum।repos.d for your repository.

Enter the following infromation
[RHEL RPM Repositroy ]
Name = private
Baseurl= URL of RPM packages (http://localhost/RPMS)
Enabled=1
Gpgcheck=0 or 1 (local system 0 ) or (GNU Public license if gpgcheck is 1)

Test it with ...yum list anypackage
You can install your packages by typing ....yum install *anypackage*

Troubleshooting concepts: Linux: Setting up a static IPAddress

System to configure static networking rather than Dynamic IPAddress
Before going to set static addressing , Please note down the following things in your network

1. IP Address of the machine
2. NETMASK and GATEWAY
3. Routing ( Default via 192.168.1.x dev eth0)
4. nameserver in the /etc/resolv.conf

1. search domain.com
2. nameserver 192.168.1.x

Bring down your network .....with ifdown eth0
Change the contents of /etc/sysconfig/network-scripts/ifcfg-eth0

Device=eth0
BOOTPROTO=None #( Don’t forget to change it from dhcp to none)
ONBOOT=yes

#Add IPAddress here :
IPADDR=192.168.1.x
#Add NETMASK
NETMASK=255.255.255.0
#Add GATEWAY
GATEWAY: 192.168.1.x

Make sure that your hostname is correct.
Open your /etc/sysconfig/network and check your hostname
HOSTNAME=Example

Verify that hostname can be resolved with out using DNS
127.0.0.1 localhost.localdomain localhost
192.168.1.2 example example.example.com

Bring up eth0 ...............ping machine...............it works ...!
Restart your machine with : shutdown -r now
ping machine.........it works...!