By issuing the command who, the output looks as shown below:
[root@bigboy tmp]# who
root pts/0 Jun 19 09:26 (reggae.my-site.com)
You can issue the command last to check.
You can truncate the output by providing the –n (n is a numerical) to display only n lines.
[root@bigboy tmp]# last -100
root pts/0 reggae.my-site.co Thu Jun 19 09:26 still logged in
root pts/0 reggae.my-site.co Wed Jun 18 01:07 – 09:26 (1+08:18)
reboot system boot 2.4.18-14 Wed Jun 18 01:07 (1+08:21)
root pts/0 reggae.my-site.co Tue Jun 17 21:57 – down (03:07)
root pts/0 reggae.my-site.co Mon Jun 16 07:24 – 00:35 (17:10)
wtmp begins Sun Jun 15 16:29:18 2003
You can use the following commands:
Service iptables status
Use the command nmap with –O option.
Ping & traceroute
Name the commands used to check the network packet details:
Tcpdump, mtr, tshark
What is the use of nslookup command?
Nslookup command is used for DNS queries. You can check the IP address of the server by passing the DNS name and vice-a-versa.
You need to check if SSH application is running on the remote system or
If there is a firewall blocking and rejecting the connection attempt
Telnet to port 22 give a Connection successful output as shown below:
[root@bigboy tmp]# telnet 192.168.1.102 22
Connected to 192.168.1.102.
Escape character is ‘^]’.
[root@ bigboy tmp]#
If you are trying to ping a host on remote network:
The network device doesn’t have a route in its routing table to the destination network and sends an ICMP reply type 3 which triggers the message. The resulting message might be Destination Host Unreachable or Destination Network Unreachable.
Run the following command from the command prompt:
NIC duplex and speed incompatibilities
An overloaded server at the remote end of the connection