sys-network-tools

# System
-   dstat  - Combines vmstat, iostat, ifstat, netstat information and more.
-   lsof  - List open files by processes.
-   dstat  - Combines vmstat, iostat, ifstat, netstat information and more
# Network
-  dig  - DNS lookup.
-  ping  - The ping command sends echo requests to the host you specify on the command line, and lists the responses received their round trip time.
-  traceroute  - traceroute will show the route of a packet. It attempts to list the series of hosts through which your packets travel on their way to a given destination.
-  nslookup  - nslookup command also use to find out DNS related query.
-  host  - host command to find name to IP or IP to name in IPv4 or IPv6 and also query DNS records.
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host google.com
google.com has address 142.250.180.206
google.com has IPv6 address 2a00:1450:400d:80a::200e
google.com mail is handled by 10 smtp.google.com.
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- arp  - ARP (Address Resolution Protocol) is useful to view / add the contents of the kernel’s ARP tables. To see default table use the command as.
  - arp -a : show current arp table.
  - arl -a -d {IP} : delete record from arp table.
- nmap  - nmap is a very advanced network tool used to query machines (local or remote) as to whether they are up and what ports are open on these machines.
- netstat(ss)  - Displays contents of /proc/net files. It works with the Linux Network Subsystem, it will tell you what the status of ports are ie. open, closed, waiting, masquerade connections.
- nslookup  - nslookup command also use to find out DNS related query.