10 July 2011

Linux comand for Network troubleshooting

Sometimes the admins and network engineers have to deal with a variety of problems on the network. I will share my experience about troubleshooting on the network by using 5 standard tool commonly used for troubleshooting the

    
ping
    
traceroute
    
netstat
    
telnet
    
tcpdump
Ping. I'm sure most of the network admin and network engineer must know the ping command. ping is used to check network connectivity. Ping uses ICMP protocol. The format of the ping command:
ping nama_host / ip_address option
For example: ping 192.168.100.1-c 10 it will be to ping the ip 192.168.100.1 10 times.
Traceroute Traceroute is used to check or trace the route network. Suppose we try to ping www.yahoo.com and the result turned out to request time out To mnegetahui rupture in our network or network provider, then we use the traceroute command.
example traceroute: traceroute www.yahoo.com
Netstat Netstat is used to check the connection happen and open ports and can also be used to view the routing table. So with netstat we can know that we use computers or servers that we are setting the connections and open ports where port whatever
example netstat: netstat-an To see the connection in any direction
netstat-tpnl To view an open TCP port
Telnet. Telnet is used to check whether the port is accessible from any clien. eg port 25 and 110 checks For example telnet: telnet 10.2.86.75 25 25 to check smtp
telnet 10.2.86.75 25 110 to check pop3
Tcpdump. Tcpdump is used to extract data packets. By knowing the data packets that pass, we can identify whether there is something wrong such as a broadcast ip or ip who try to do activities that are not allowed
tcpdump examples: tcpdump-vv to perform packet sniffing tcpdump-i eth0 for sniffing packets on interface eth0 tcpdump host alinuxnews for sniffing host alinuxnews