wget is a very good utility to download large files or iso images.
When downloading large file or DVD iso, you can use wget -c ‘url to iso file’ which you can resume download from where you left last time.

Sometimes there are scuh links which keep a lot of garbege, and using wget -c ‘url to iso file’ causes a new thread a new download instead of resuming.
In such a case you can use wget -c ‘url to iso’ -O my-dvd.iso

Using -O file name downloads file with file name and always can be resumed.

Anuj

Here we will be connecting two linux machines, of which ISP is blocking ports.

On the machine behind the blocked ports:

Download hamachi for linux.

https://secure.logmein.com/products/hamachi/list.asp

I have hamachi-0.9.9.9-20-lnx.tar.gz

• Uncompress tar file with
  tar zxvf hamachi-0.9.9.9-20-lnx.tar.gz -C /usr/src/
• Change directory
  cd /usr/src/hamachi-0.9.9.9-20-lnx/
• Install hamachi
  make install
• Run tuncfg command
  tuncfg
• Generate crypto identity
  hamachi-init
• Start hamachi daemon
  hamachi start
• Put hamachi daemon online
  hamachi login
• Create hamachi network
  /usr/bin/hamachi create myHamNetwork password
• Now become online in created network
  /usr/bin/hamachi go-online myHamNetwork

  Follow these steps on the machine from which you want to connect to the blocked machine:

• Download hamachi for linux.https://secure.logmein.com/products/hamachi/list.aspI have hamachi-0.9.9.9-20-lnx.tar.gz
• Uncompress tar file with
  tar zxvf hamachi-0.9.9.9-20-lnx.tar.gz -C /usr/src/
• Change directory
  cd /usr/src/hamachi-0.9.9.9-20-lnx/
• Install hamachi
  make install
• Run tuncfg command
  tuncfg
• Generate crypto identity
  hamachi-init
• Start hamachi daemon
  hamachi start
• Put hamachi daemon online
  hamachi login
• Join the hamachi network
  hamachi join myHamNetwork
• You will be prompted for the password of myHamNetwork, in earlier steps we defined password as ‘password’ on machine behind blocked ports.
• Check the list of hamachi network with
  hamachi list
  * [myHamNetwork]
  * 5.66.11.169                                 118.94.50.194:32774
  Here we can see 5.66.11.169 is th
• Now become online in created network
  /usr/bin/hamachi go-online myHamNetwork
• a
• hamachi-init

Following steps will give you sify client on linux, working with an automatic connectivity, you need to be root.

1. Create a directory where we will be keeping sifyconnect related files or scripts.
   mkdir /usr/src/sify
2. Change directory
   cd /usr/src/sify
3. Download sifyclient from http://thegoan.com/supersify/
   wget http://thegoan.com/supersify/supersify.zip
4. unzip downloaded sify client.
   unzip supersify.zip
5. I modified the provided ss.sh script just as for my needs, there may be some other method. Just added ‘cd /usr/src/sify’ line as first line to ss.sh.

   cd /usr/src/sify
   java -jar supersify.jar $*
   if [ $? -eq 1 ]
   then read
   fi

6. Created a second script to login without providing password every time#!/bin/bash
   #
   #Change USERNAME, PASSWORD and ETH according to your system and user/pass
   #Change ETH with the ethernet card connecting to sify ISP
   #mail me: anuj.unix@gmail.com
   #Ends.
   USERNAME=my_sify_username
   PASSWORD=my_sify_password
   ETH=eth1
   #Get the mac address here
   MAC_SIFY=`ifconfig  $ETH |grep HWaddr|cut -d ” ” -f 11`
   if [ "$#" -ne 1 ];then
   echo “To connect: `basename $0` -c ”
   echo “To disconnect: `basename $0` -d ”
   exit
   fi
   #Change directory where we unzipped the supersify.zip
   cd /usr/src/sify

   #To connect sify
   if [ "$1" = "-c" ];then
   /bin/sh ss.sh -u “$USERNAME” -p “$PASSWORD” -m $MAC_SIFY
   #To disconnect sify
   else if [ "$1" = "-d" ];then
   echo “Logging out from sify”
   /bin/sh ss.sh -l
   else
   echo “To connect: `basename $0` -c ”
   echo “To disconnect: `basename $0` -d ”
   exit
   fi
   fi

7. chmod the script
   chmod 700 /usr/bin/sifyconnect
8. To check the internet connectivity create one more script, f.e. /usr/bin/sifychk#!/bin/bash
   #
   #to check the internet connection

   ping -c 4 google.com

   if [ "$?" -ne 0 ];then
   /usr/bin/sifyconnect -c
   else
   exit
   fi

9. chmod 755 /usr/bin/sifychk
10. Add an entry in cron to automatically try to connect in case you are disconnected. Following crontab entry will check the internet connectivity every minute and connect automatically in case of disconnection. Obviously network cable and ISP should be reachable.crontab -e
    * * * * * /usr/bin/sifychk >/dev/null 2>&1

That’s it.

Anuj Singh.

Channel bonding treats multiple physical connections to switch units as a single logical link.

1. Create /etc/sysconfig/network-scripts/ifcfg-bond0 file with following entries:

2. Create an ifcfg-ethn file for each interface in the bond.

l Our /etc/sysconfig/network-scripts/ifcfg-eth0 file

2 Our /etc/sysconfig/network-scripts/ifcfg-eth1 file

3. Add the following lines to /etc/modules.conf:

4. restart networking

public key based authentication

Objective: To run a command on a remote linux machine without entering a password.

Remote Linux Machine (10.1.10.6)

Local Machine (10.1.10.20)

Steps for Local Machine:

1. Generate a public key with command

ssh-keygen -t dsa

Generating public/private dsa key pair.
Enter file in which to save the key (/home/anuj/.ssh/id_dsa):
Created directory '/home/anuj/.ssh'.
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/anuj/.ssh/id_dsa.
Your public key has been saved in /home/anuj/.ssh/id_dsa.pub.
The key fingerprint is:
6e:c0:f4:ad:d7:97:37:e6:09:9a:56:ee:79:48:5f:92 anuj@node2.example.com

Copy generated ‘id_dsa.pub‘ on remote server as ‘authorized_keys’ in ‘.ssh’ under the home directory of intended user for remote command execution. Here in example remote user being used is ‘root‘ of remote machine 10.1.10..6

scp .ssh/id_dsa.pub root@10.1.10.6:.ssh/authorized_keys

The authenticity of host '10.1.10.6 (10.1.10.6)' can't be established.
RSA key fingerprint is 5d:17:94:69:22:6b:c0:99:79:c2:ff:7e:2d:86:9b:d7.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '10.1.10.6' (RSA) to the list of known hosts.
root@10.1.10.6's password:
id_dsa.pub                            100%  617     0.6KB/s   00:00

Test the configuration by executing some command as follows: (example command used is ‘uptime‘

 ssh root@10.1.10.6  uptime

 12:14:43 up  23:18,  0 users,  load average: 0.00, 0.03, 0.05

anujhere@gmail.com