You can see the parameter settings for the network card, such connection status, speed, duplex mode, by using command ethtool
You can also see the driver (kernel module) attached to the network card:
By using ethtool, configure the network interface for 100 MBit half-duplex, 10 MBit half-duplex modes, then autonegotiate for the default mode.
Renew the IP address lease:
Alternatively, you can renew the lease by restarting the network script:
Every time when you are trying to access any remote machine via TCP/IP, your ARP cash gets updated first, then the MAC address of the remote host, or the gateway if the host is located outside of your subnet, is used to deliver the ethernet frame.
This shows you all the gateways between the subnets your packet travels towards the destination (engsoft.rutgers.edu for example).
Ask your neighbor to reconfigure his machine on the same network (126.96.36.199/24 ); try to ping each other machines. Make sure you are using different IP addresses on the same subnet. Try to ping any machine on the original subnet, 192.168.5.0/24 As you understand, there is no routing set between subnets 188.8.131.52/24 and 192.168.5.0/24 so you can't pass network packets between them.
Do the same network re-configuration using the network scipt file. Edit file /etc/network/interfaces and put the following settings there:
Restart the network:
Finally, configure your machine for the original network settings in /etc/network/interfaces:
Restart the network:
The "node" computer is located on the left side with the same m your desktop. It has the same number as your desktop. For example if you are on desktop04, your node is node04. Make sure the IP address of the node is listed in file /etc/hosts on your desktop: the IP addresses run from 192.168.5.21 to 192.168.5.36 for node01 to node16, accordingly.
ssh to the node as user hostadm:
Check /etc/inetd.conf and make sure you see the following entry:
Command netstat -na should show open tcp/23 port:
Telnet to the node from your desktop machine, for example:
Check out /etc/inetd.conf and notice the entry for FTP:
Command netstat -na shows open tcp/21 port:
From the desktop, ftp to the node.
Use hostadm user credentials (login name and password).
For SSH authentication, you can use either RSA or DSA public/private keys besides password. We'll be using RSA in the exercises below.
To generate an RSA key pair, type the following command at a shell prompt on your desktop:
Accept the default file location of ~/.ssh/id_rsa. Enter a passphrase different from your account password and confirm it by entering it again.
The public key is written to ~/.ssh/id_rsa.pub. The private key is written to ~/.ssh/id_rsa.
Never distribute your private key to anyone.
The contents of ~/.ssh/id_rsa.pub needs to be delivered onto the remote machine to which you want to connect, specifically the node, into file ~/.ssh/authorized_keys
To accomplish the transfer task, here you can use ftp service installed in the previous exercise.
Command cd in the ftp> shell above is for stepping into the directory, .ssh, on the remote host, node04.
Command lcd is for stepping into the directory, .ssh, on the local desktop.
Now try to ssh to the node. You should be prompted to enter your passphrase.
The ssh-agent can be used to store your passphrase so that you do not have to enter it each time you make a ssh or scp connection.
At a shell prompt on the desktop, type the following command:
Then type the command:
and enter your passphrase(s). If you have more than one key pair configured, you will be prompted for each one. When you log out, your passphrase(s) will be forgotten. You must execute these two commands each time you log in to a virtual console or open a terminal window.
Copy files from your desktop to the node and vise versa using scp command:
This tool lets you copy files and directories between a local host and a remote host.
Install rsync on your desktop:
Creat a directory tree and copy it over to the node with rsync command.
Option a stands for archive (preserve links and timestamps); v is for verbose and z is for data compression when sending-receiving.
Since you have fully functioning SSH on the node, you can get rid of telnet and ftp servers. In file /etc/inetd.conf comment-out the lines for telnet and ftp. Make inetd daemon to re-read the modified /etc/inetd.conf by executing the following command:
where the process ID, inetd_PID, for inetd can be found from
Alternatively, you can simply run
Make sure ports tcp/21, tcp/23 are not open by running
Never run rsh, rlogin, telnet and ftp servers on the open Internet. They are very unsecure due to clear text authentication and data transfer.