vmstat – Virtual memory statistics

 The vmstat command reports information about processes, memory, paging, block IO, traps, and cpu activity.

vmstat 3
Sample Outputs:

procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu------
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
 0  0      0 2540988 522188 5130400    0    0     2    32    4    2  4  1 96  0  0
 1  0      0 2540988 522188 5130400    0    0     0   720 1199  665  1  0 99  0  0
 0  0      0 2540956 522188 5130400    0    0     0     0 1151 1569  4  1 95  0  0
 0  0      0 2540956 522188 5130500    0    0     0     6 1117  439  1  0 99  0  0
 0  0      0 2540940 522188 5130512    0    0     0   536 1189  932  1  0 98  0  0
 0  0      0 2538444 522188 5130588    0    0     0     0 1187 1417  4  1 96  0  0
 0  0      0 2490060 522188 5130640    0    0     0    18 1253 1123  5  1 94  0  0

Display Memory Utilization Slabinfo

vmstat -m

Get Information About Active / Inactive Memory Pages

vmstat -a

Linux Find Out What Process Are Using Swap Space

Use the smem command:

smem
Another option is to combine pgrep command with the grep command to find out SWAP mem usage:
pgrep memcached


grep --color VmSwap /proc/48440/status

Linux Find Out What Process Are Using Swap Space

top – Process activity monitoring command

top command display Linux processes. It provides a dynamic real-time view of a running system i.e. actual process activity. By default, it displays the most CPU-intensive tasks running on the server and updates the list every five seconds.

Fig.01: Linux top command

Commonly Used Hot Keys With top Linux monitoring tools

Here is a list of useful hot keys:

Hot Key	Usage
t	Displays summary information off and on.
m	Displays memory information off and on.
A	Sorts the display by top consumers of various system resources. Useful for quick identification of performance-hungry tasks on a system.
f	Enters an interactive configuration screen for top. Helpful for setting up top for a specific task.
o	Enables you to interactively select the ordering within top.
r	Issues renice command.
k	Issues kill command.
z	Turn on or off color/mono

 

Nmap Command Examples For Linux Sys/Network Admins

 Nmap is short for Network Mapper. It is an open-source security tool for network exploration, security scanning, and auditing. However, the Nmap command comes with lots of options that can make the utility more robust and difficult to follow for new users. The purpose of this guide is to introduce a user to the Nmap command line tool to scan a host or network to find out the possible vulnerable points in the hosts. You will also learn how to use Nmap for offensive and defensive purposes. Let us see some common and practial nmap examples running on Linux or Unix-like systems.

What is Nmap and what is it used for?

From the man page:

Nmap (“Network Mapper”) is an open source tool for network exploration and security auditing. It was designed to rapidly scan large networks, although it works fine against single hosts. Nmap uses raw IP packets in novel ways to determine what hosts are available on the network, what services (application name and version) those hosts are offering, what operating systems (and OS versions) they are running, what type of packet filters/firewalls are in use, and dozens of other characteristics. While Nmap is commonly used for security audits, many systems and network administrators find it useful for routine tasks such as network inventory, managing service upgrade schedules, and monitoring host or service uptime.

It was originally written by Gordon Lyon and it can answer the following questions easily:

1. Find running computers on the local network
2. What IP addresses did you find running on the local network?
3. Discover the operating system of your target machine
4. Find out what ports are open on the machine that you just scanned?
5. See if the system is infected with malware or virus.
6. Search for unauthorized servers or network service on your network.
7. Locate and remove computers which don’t meet the organization’s minimum level of security.

Nmap Command Examples in Linux and Unix – Sample setup (LAB) for

Port scanning may be illegal in some jurisdictions. So setup a lab as follows to run nmap examples for learning purposes:

                              +---------+
        +---------+           | Network |         +--------+
        | server1 |-----------+ swtich  +---------|server2 |
        +---------+           | (sw0)   |         +--------+
                              +----+----+
                                   | 
                                   |
                         +---------+----------------+
                         | wks01 Linux/macOS/Win    |
                         +--------------------------+

Where,

• wks01 is your computer either running Linux/macOS (OS X) or Unix like operating system. It is used for scanning your local network. The nmap command must be installed on this computer and you are going to type all nmap examples metnioned here.
• server1 can be powered by Linux / Unix / MS-Windows operating systems. This is an unpatched server. Feel free to install a few services such as a web-server, FTP or file server and so on.
• server2 can be powered by Linux / Unix / MS-Windows operating systems. This is a fully patched server with firewall. Again, feel free to install few services such as a web-server, file server and so on.
• All three systems are connected via a network switch.

Let us get our hands on dirty with nmap examples. Please note that many examples needs to be run by the root user.

1. Scan a single host or an IP address (IPv4) using nmap

The most simplest nmap examples is to scan a single machine. For example:

### Scan a single ip address ###
nmap 192.168.1.1
 
## Scan a host name ###
nmap server1.cyberciti.biz
 
## Scan a host name with more info###
nmap -v server1.cyberciti.biz

Fig.01: nmap output

2. Scan multiple IP address or subnet (IPv4)

In this nmap example we are going to scan many IP address or CIDR. For instance:

# Nmap scan network example #
nmap 192.168.1.1 192.168.1.2 192.168.1.3
## works with same subnet i.e. 192.168.1.0/24 
nmap 192.168.1.1,2,3

You can scan a range of IP address too:

nmap 192.168.1.1-20

You can scan a range of IP address using a wildcard:

nmap 192.168.1.*

Finally, you scan an entire subnet:

nmap 192.168.1.0/24

3. Read list of hosts/networks from a file (IPv4)

The -iL option allows you to read the list of target systems using a text file. This is useful to scan a large number of hosts/networks. For example, create a text file as follows using the cat command:
cat > /tmp/test.txt
Append host names, CIDRs or IP address names as follows:

server1.cyberciti.biz
192.168.1.0/24
192.168.1.1/24
10.1.2.3
localhost

Press the CTRL+D to save the file. Now, the syntax is as follows:

nmap -iL /tmp/test.txt

The above nmap example will scan server1.cyberciti.biz, and given CIDRs and the scan might take some time.

4. Excluding hosts/networks (IPv4) from nmap scan examples

When scanning a large number of hosts/networks you can exclude hosts from a scan. For examples:

nmap 192.168.1.0/24 --exclude 192.168.1.5
nmap 192.168.1.0/24 --exclude 192.168.1.5,192.168.1.254

OR exclude list from a file called /tmp/exclude.txt

nmap -iL /tmp/scanlist.txt --excludefile /tmp/exclude.txt

5. Turn on OS and version detection scanning script (IPv4) with nmap examples

Run the following command

nmap -A 192.168.1.254
nmap -v -A 192.168.1.1
nmap -A -iL /tmp/scanlist.txt 

6. Find out if a host/network is protected by a firewall using namp command

## nmap command examples for your host ##
nmap -sA 192.168.1.254
nmap -sA server1.cyberciti.biz

7. Scaning a host when protected by the firewall

In this Nmap command examples we are going to scan a router/wifi device having 192.168.1.1 as IP:

nmap -PN 192.168.1.1
nmap -PN server1.cyberciti.biz

8. Scan an IPv6 host/address examples

The -6 option enable IPv6 scanning with the namp command. The syntax is:

nmap -6 IPv6-Address-Here
nmap -6 server1.cyberciti.biz
nmap -6 2607:f0d0:1002:51::4
nmap -v A -6 2607:f0d0:1002:51::4

9. Scan a network and find out which servers and devices are up and running

This is known as host discovery or ping scan. Try the followin nmap examples:

nmap -sP 192.168.1.0/24

Here is how it looks:

Host 192.168.1.1 is up (0.00035s latency).
MAC Address: BC:AE:C5:C3:16:93 (Unknown)
Host 192.168.1.2 is up (0.0038s latency).
MAC Address: 74:44:01:40:57:FB (Unknown)
Host 192.168.1.5 is up.
Host nas03 (192.168.1.12) is up (0.0091s latency).
MAC Address: 00:11:32:11:15:FC (Synology Incorporated)
Nmap done: 256 IP addresses (4 hosts up) scanned in 2.80 second

10. How do I perform a fast scan using the namp?

Open the terminal app and then run the following nmap examples:

nmap -F 192.168.1.1
nmap -6 -F IPv6_Address_Here

11. Display the reason a port is in a particular state
nmap --reason 192.168.1.1
nmap --reason server1.cyberciti.biz
Outputs:
Starting Nmap 7.80 ( https://nmap.org ) at 2020-05-07 21:16 IST
Nmap scan report for router (192.168.2.254)
Host is up, received arp-response (0.00026s latency).
Not shown: 995 filtered ports
Reason: 995 no-responses
PORT    STATE SERVICE REASON
22/tcp  open  ssh     syn-ack ttl 64
53/tcp  open  domain  syn-ack ttl 64
80/tcp  open  http    syn-ack ttl 64
443/tcp open  https   syn-ack ttl 64
666/tcp open  doom    syn-ack ttl 64
MAC Address: 00:08:A2:0D:05:41 (ADI Engineering)
 
Nmap done: 1 IP address (1 host up) scanned in 4.85 seconds
12. Only show open (or possibly open) ports using nmap command in Linux
Run:
nmap --open 192.168.1.1
nmap --open server1.cyberciti.biz
nmap --open 192.168.2.18
Scan outputs from my CentOS 7 Linux server:
Starting Nmap 7.80 ( https://nmap.org ) at 2020-05-07 21:17 IST
Nmap scan report for centos7 (192.168.2.18)
Host is up (0.00015s latency).
Not shown: 998 filtered ports, 1 closed port
Some closed ports may be reported as filtered due to --defeat-rst-ratelimit
PORT   STATE SERVICE
22/tcp open  ssh
MAC Address: 00:01:C0:1B:28:7E (CompuLab)
 
Nmap done: 1 IP address (1 host up) scanned in 5.07 seconds
13. Show all packets sent and received
nmap --packet-trace 192.168.1.1
nmap --packet-trace server1.cyberciti.biz
14. Show host interfaces and routes namp examples
This is useful for debugging (ip command or route command or netstat command like output using the nmap command on Linux)
nmap --iflist
Detailed report created by the Namp command:
Starting Nmap 5.00 ( http://nmap.org ) at 2012-11-27 02:01 IST
************************INTERFACES************************
DEV    (SHORT)  IP/MASK          TYPE        UP MAC
lo     (lo)     127.0.0.1/8      loopback    up
eth0   (eth0)   192.168.1.5/24   ethernet    up B8:AC:6F:65:31:E5
vmnet1 (vmnet1) 192.168.121.1/24 ethernet    up 00:50:56:C0:00:01
vmnet8 (vmnet8) 192.168.179.1/24 ethernet    up 00:50:56:C0:00:08
ppp0   (ppp0)   10.1.19.69/32    point2point up
 
**************************ROUTES**************************
DST/MASK         DEV    GATEWAY
10.0.31.178/32   ppp0
209.133.67.35/32 eth0   192.168.1.2
192.168.1.0/0    eth0
192.168.121.0/0  vmnet1
192.168.179.0/0  vmnet8
169.254.0.0/0    eth0
10.0.0.0/0       ppp0
0.0.0.0/0        eth0   192.168.1.2
15. How do I scan specific ports using nmap?
In this example, I am going to use nmap to scan TCP or UDP ports. You can find a list of all services and ports in the /etc/services file. For example:

more /etc/services

Now try the following nample examples to prob for TCP port 80 and others:
nmap -p [port] hostName
## Scan port 80
nmap -p 80 192.168.1.1
 
## Scan TCP port 80
nmap -p T:80 192.168.1.1
 
## Scan UDP port 53
nmap -p U:53 192.168.1.1
 
## Scan two ports ##
nmap -p 80,443 192.168.1.1
 
## Scan port ranges ##
nmap -p 80-200 192.168.1.1
 
## Combine all options ##
nmap -p U:53,111,137,T:21-25,80,139,8080 192.168.1.1
nmap -p U:53,111,137,T:21-25,80,139,8080 server1.cyberciti.biz
nmap -v -sU -sT -p U:53,111,137,T:21-25,80,139,8080 192.168.1.254
 
## Scan all ports with * wildcard ##
nmap -p "*" 192.168.1.1
 
## Scan top ports i.e. scan $number most common ports ##
nmap --top-ports 5 192.168.1.1
nmap --top-ports 10 192.168.1.1
Sample outputs:
Starting Nmap 5.00 ( http://nmap.org ) at 2012-11-27 01:23 IST
Interesting ports on 192.168.1.1:
PORT     STATE  SERVICE
21/tcp   closed ftp
22/tcp   open   ssh
23/tcp   closed telnet
25/tcp   closed smtp
80/tcp   open   http
110/tcp  closed pop3
139/tcp  closed netbios-ssn
443/tcp  closed https
445/tcp  closed microsoft-ds
3389/tcp closed ms-term-serv
MAC Address: BC:AE:C5:C3:16:93 (Unknown)
 
Nmap done: 1 IP address (1 host up) scanned in 0.51 seconds
16: The fastest way to scan all your devices/computers for open ports ever
Here is a nmap example that scan all your devices on the network. For example:
nmap -T5 192.168.1.0/24
nmap -T5 {sub/net}
nmap -T5 CIDR
17. How do I detect remote operating system with the help of nmap?
You can identify a remote host apps and OS using the -O option. Try the following namp examples:
nmap -O 192.168.1.1
nmap -O  --osscan-guess 192.168.1.1
nmap -v -O --osscan-guess 192.168.1.1
Sample outputs:
Starting Nmap 5.00 ( http://nmap.org ) at 2012-11-27 01:29 IST
NSE: Loaded 0 scripts for scanning.
Initiating ARP Ping Scan at 01:29
Scanning 192.168.1.1 [1 port]
Completed ARP Ping Scan at 01:29, 0.01s elapsed (1 total hosts)
Initiating Parallel DNS resolution of 1 host. at 01:29
Completed Parallel DNS resolution of 1 host. at 01:29, 0.22s elapsed
Initiating SYN Stealth Scan at 01:29
Scanning 192.168.1.1 [1000 ports]
Discovered open port 80/tcp on 192.168.1.1
Discovered open port 22/tcp on 192.168.1.1
Completed SYN Stealth Scan at 01:29, 0.16s elapsed (1000 total ports)
Initiating OS detection (try #1) against 192.168.1.1
Retrying OS detection (try #2) against 192.168.1.1
Retrying OS detection (try #3) against 192.168.1.1
Retrying OS detection (try #4) against 192.168.1.1
Retrying OS detection (try #5) against 192.168.1.1
Host 192.168.1.1 is up (0.00049s latency).
Interesting ports on 192.168.1.1:
Not shown: 998 closed ports
PORT   STATE SERVICE
22/tcp open  ssh
80/tcp open  http
MAC Address: BC:AE:C5:C3:16:93 (Unknown)
Device type: WAP|general purpose|router|printer|broadband router
Running (JUST GUESSING) : Linksys Linux 2.4.X (95%), Linux 2.4.X|2.6.X (94%), MikroTik RouterOS 3.X (92%), Lexmark embedded (90%), Enterasys embedded (89%), D-Link Linux 2.4.X (89%), Netgear Linux 2.4.X (89%)
Aggressive OS guesses: OpenWrt White Russian 0.9 (Linux 2.4.30) (95%), OpenWrt 0.9 - 7.09 (Linux 2.4.30 - 2.4.34) (94%), OpenWrt Kamikaze 7.09 (Linux 2.6.22) (94%), Linux 2.4.21 - 2.4.31 (likely embedded) (92%), Linux 2.6.15 - 2.6.23 (embedded) (92%), Linux 2.6.15 - 2.6.24 (92%), MikroTik RouterOS 3.0beta5 (92%), MikroTik RouterOS 3.17 (92%), Linux 2.6.24 (91%), Linux 2.6.22 (90%)
No exact OS matches for host (If you know what OS is running on it, see http://nmap.org/submit/ ).
TCP/IP fingerprint:
OS:SCAN(V=5.00%D=11/27%OT=22%CT=1%CU=30609%PV=Y%DS=1%G=Y%M=BCAEC5%TM=50B3CA
OS:4B%P=x86_64-unknown-linux-gnu)SEQ(SP=C8%GCD=1%ISR=CB%TI=Z%CI=Z%II=I%TS=7
OS:)OPS(O1=M2300ST11NW2%O2=M2300ST11NW2%O3=M2300NNT11NW2%O4=M2300ST11NW2%O5
OS:=M2300ST11NW2%O6=M2300ST11)WIN(W1=45E8%W2=45E8%W3=45E8%W4=45E8%W5=45E8%W
OS:6=45E8)ECN(R=Y%DF=Y%T=40%W=4600%O=M2300NNSNW2%CC=N%Q=)T1(R=Y%DF=Y%T=40%S
OS:=O%A=S+%F=AS%RD=0%Q=)T2(R=N)T3(R=N)T4(R=Y%DF=Y%T=40%W=0%S=A%A=Z%F=R%O=%R
OS:D=0%Q=)T5(R=Y%DF=Y%T=40%W=0%S=Z%A=S+%F=AR%O=%RD=0%Q=)T6(R=Y%DF=Y%T=40%W=
OS:0%S=A%A=Z%F=R%O=%RD=0%Q=)T7(R=N)U1(R=Y%DF=N%T=40%IPL=164%UN=0%RIPL=G%RID
OS:=G%RIPCK=G%RUCK=G%RUD=G)IE(R=Y%DFI=N%T=40%CD=S)
Uptime guess: 12.990 days (since Wed Nov 14 01:44:40 2012)
Network Distance: 1 hop
TCP Sequence Prediction: Difficulty=200 (Good luck!)
IP ID Sequence Generation: All zeros
Read data files from: /usr/share/nmap
OS detection performed. Please report any incorrect results at http://nmap.org/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 12.38 seconds
           Raw packets sent: 1126 (53.832KB) | Rcvd: 1066 (46.100KB)

Also see Fingerprinting a web-server and a dns server command line tools for more information.
18. How do I detect remote services (server / daemon) version numbers?
Open the terminal and then type the following nmap command:
nmap -sV 192.168.1.1
Sample outputs:
Starting Nmap 5.00 ( http://nmap.org ) at 2012-11-27 01:34 IST
Interesting ports on 192.168.1.1:
Not shown: 998 closed ports
PORT   STATE SERVICE VERSION
22/tcp open  ssh     Dropbear sshd 0.52 (protocol 2.0)
80/tcp open  http?
1 service unrecognized despite returning data.

19. Scan a host using TCP ACK (PA) and TCP Syn (PS) ping
If firewall is blocking standard ICMP pings, try the following host discovery methods:
nmap -PS 192.168.1.1
nmap -PS 80,21,443 192.168.1.1
nmap -PA 192.168.1.1
nmap -PA 80,21,200-512 192.168.1.1
20. Scan a host using IP protocol ping
The nmap commands are as follows:
sudo nmap -PO 192.168.1.1
sudo nmap -PO 192.168.2.254
Sample session:
Starting Nmap 7.80 ( https://nmap.org ) at 2022-08-01 06:59 IST
Stats: 0:00:01 elapsed; 0 hosts completed (1 up), 1 undergoing SYN Stealth Scan
SYN Stealth Scan Timing: About 0.65% done
Nmap scan report for router (192.168.2.254)
Host is up (0.00034s latency).
Not shown: 996 filtered ports
PORT    STATE SERVICE
22/tcp  open  ssh
53/tcp  open  domain
80/tcp  open  http
443/tcp open  https
MAC Address: 00:08:A2:0D:05:41 (ADI Engineering)

Nmap done: 1 IP address (1 host up) scanned in 4.85 seconds
21. Scan a host using UDP ping
The following nmap examples scan bypasses firewalls and filters that only screen TCP. Try it out:
nmap -PU 192.168.1.1
nmap -PU 2000.2001 192.168.1.1
22. Find out the most commonly used TCP ports using TCP SYN Nmap Scan examples
For instnace:
### Stealthy scan ###
nmap -sS 192.168.1.1
 
### Find out the most commonly used TCP ports using  TCP connect scan (warning: no stealth scan)
###  OS Fingerprinting ###
nmap -sT 192.168.1.1
 
### Find out the most commonly used TCP ports using TCP ACK scan
nmap -sA 192.168.1.1
 
### Find out the most commonly used TCP ports using TCP Window scan
nmap -sW 192.168.1.1
 
### Find out the most commonly used TCP ports using TCP Maimon scan
nmap -sM 192.168.1.1
23. Scan a host for UDP services (UDP scan) examples
Most popular services on the Internet run over the TCP protocol. DNS,
 SNMP, and DHCP are three of the most common UDP services. Use the 
following syntax to find out UDP services:
nmap -sU nas03
nmap -sU 192.168.1.1
Sample outputs:
Starting Nmap 5.00 ( http://nmap.org ) at 2012-11-27 00:52 IST
Stats: 0:05:29 elapsed; 0 hosts completed (1 up), 1 undergoing UDP Scan
UDP Scan Timing: About 32.49% done; ETC: 01:09 (0:11:26 remaining)
Interesting ports on nas03 (192.168.1.12):
Not shown: 995 closed ports
PORT     STATE         SERVICE
111/udp  open|filtered rpcbind
123/udp  open|filtered ntp
161/udp  open|filtered snmp
2049/udp open|filtered nfs
5353/udp open|filtered zeroconf
MAC Address: 00:11:32:11:15:FC (Synology Incorporated)
 
Nmap done: 1 IP address (1 host up) scanned in 1099.55 seconds
24. Scan for IP protocol nmap examples
This type of scan allows you to determine which IP protocols (TCP, ICMP, IGMP, etc.) are supported by target machines:
nmap -sO 192.168.1.1
25. Scan a firewall for security weakness
The following scan types exploit a subtle loophole in the TCP and good for testing security of common attacks:
## TCP Null Scan to fool a firewall to generate a response ##
## Does not set any bits (TCP flag header is 0) ##
nmap -sN 192.168.1.254
 
## TCP Fin scan to check firewall ##
## Sets just the TCP FIN bit ##
nmap -sF 192.168.1.254
 
## TCP Xmas scan to check firewall ##
## Sets the FIN, PSH, and URG flags, lighting the packet up like a Christmas tree ##
nmap -sX 192.168.1.254
See how to block Xmas packkets, syn-floods and other conman attacks with iptables.
26. Scan a firewall for packets fragments
The -f option causes the requested scan (including ping scans) to use
 tiny fragmented IP packets. The idea is to split up the TCP header over

several packets to make it harder for packet filters, intrusion 
detection systems, and other annoyances to detect what you are doing.
nmap -f 192.168.1.1
nmap -f fw2.nixcraft.net.in
nmap -f 15 fw2.nixcraft.net.in

## Set your own offset size with the --mtu option ##
nmap --mtu 32 192.168.1.1

27. Cloak a scan with decoys namp examples
The -D option it appear to the remote host that the host(s) you specify as decoys are scanning the target network too.
 Thus their IDS might report 5-10 port scans from unique IP addresses, 
but they won’t know which IP was scanning them and which were innocent 
decoys:
nmap -n -Ddecoy-ip1,decoy-ip2,your-own-ip,decoy-ip3,decoy-ip4 remote-host-ip
nmap -n -D192.168.1.5,10.5.1.2,172.1.2.4,3.4.2.1 192.168.1.5
28. Scan a firewall for MAC address spoofing nmap examples
Type the following command:
### Spoof your MAC address ##
nmap --spoof-mac MAC-ADDRESS-HERE 192.168.1.1
 
### Add other options ###
nmap -v -sT -PN --spoof-mac MAC-ADDRESS-HERE 192.168.1.1
 
 
### Use a random MAC address ###
### The number 0, means nmap chooses a completely random MAC address ###
nmap -v -sT -PN --spoof-mac 0 192.168.1.1
29. How do I save output to a text file?
The syntax is as follows:
nmap 192.168.1.1 > output.txt
nmap -oN /path/to/filename 192.168.1.1
nmap -oN output.txt 192.168.1.1

The use the more/cat/less or bat command as follows:

less output.txt
30. Scans for web servers and pipes into Nikto for scanning
In this namp examples, I am going to use the Nikto:

nmap -p80 192.168.1.2/24 -oG - | /path/to/nikto.pl -h -

nmap -p80,443 192.168.1.2/24 -oG - | /path/to/nikto.pl -h -
31. Speed up nmap scan examples
Pass the -T option to the nmap command:

nmap -v -sS -A -T4 192.168.2.5

Sample outputs:
Starting Nmap 7.40 ( https://nmap.org ) at 2017-05-15 01:52 IST
NSE: Loaded 143 scripts for scanning.
NSE: Script Pre-scanning.
Initiating NSE at 01:52
Completed NSE at 01:52, 0.00s elapsed
Initiating NSE at 01:52
Completed NSE at 01:52, 0.00s elapsed
Initiating ARP Ping Scan at 01:52
Scanning 192.168.2.15 [1 port]
Completed ARP Ping Scan at 01:52, 0.01s elapsed (1 total hosts)
Initiating SYN Stealth Scan at 01:52
Scanning dellm6700 (192.168.2.15) [1000 ports]
Discovered open port 5900/tcp on 192.168.2.15
Discovered open port 80/tcp on 192.168.2.15
Discovered open port 22/tcp on 192.168.2.15
Completed SYN Stealth Scan at 01:53, 4.62s elapsed (1000 total ports)
Initiating Service scan at 01:53
Scanning 3 services on dellm6700 (192.168.2.15)
Completed Service scan at 01:53, 6.01s elapsed (3 services on 1 host)
Initiating OS detection (try #1) against dellm6700 (192.168.2.15)
Retrying OS detection (try #2) against dellm6700 (192.168.2.15)
NSE: Script scanning 192.168.2.15.
Initiating NSE at 01:53
Completed NSE at 01:53, 30.02s elapsed
Initiating NSE at 01:53
Completed NSE at 01:53, 0.00s elapsed
Nmap scan report for dellm6700 (192.168.2.15)
Host is up (0.00044s latency).
Not shown: 996 filtered ports
PORT     STATE  SERVICE VERSION
22/tcp   open   ssh     (protocol 2.0)
| fingerprint-strings: 
|   NULL: 
|_    SSH-2.0-OpenSSH_7.4p1 Ubuntu-10
| ssh-hostkey: 
|   2048 1d:14:84:f0:c7:21:10:0e:30:d9:f9:59:6b:c3:95:97 (RSA)
|_  256 dc:59:c6:6e:33:33:f2:d2:5d:9b:fd:b4:9c:52:c1:0a (ECDSA)
80/tcp   open   http    nginx 1.10.0 (Ubuntu)
| http-methods: 
|_  Supported Methods: GET HEAD
|_http-server-header: nginx/1.10.0 (Ubuntu)
|_http-title: Apache2 Ubuntu Default Page: It works
443/tcp  closed https
5900/tcp open   vnc     VNC (protocol 3.7)
1 service unrecognized despite returning data. If you know the service/version, please submit the following fingerprint at https://nmap.org/cgi-bin/submit.cgi?new-service :
SF-Port22-TCP:V=7.40%I=7%D=5/15%Time=5918BCAA%P=x86_64-apple-darwin16.3.0%
SF:r(NULL,20,"SSH-2\.0-OpenSSH_7\.4p1\x20Ubuntu-10\n");
MAC Address: F0:1F:AF:1F:2C:60 (Dell)
Device type: general purpose
Running (JUST GUESSING): Linux 3.X|4.X|2.6.X (95%), OpenBSD 4.X (85%)
OS CPE: cpe:/o:linux:linux_kernel:3 cpe:/o:linux:linux_kernel:4 cpe:/o:linux:linux_kernel:2.6.32 cpe:/o:openbsd:openbsd:4.0
Aggressive OS guesses: Linux 3.11 - 4.1 (95%), Linux 4.4 (95%), Linux 3.13 (92%), Linux 4.0 (90%), Linux 2.6.32 (89%), Linux 2.6.32 or 3.10 (89%), Linux 3.2 - 3.8 (89%), Linux 3.10 - 3.12 (88%), Linux 2.6.32 - 2.6.33 (87%), Linux 2.6.32 - 2.6.35 (87%)
No exact OS matches for host (test conditions non-ideal).
Uptime guess: 0.000 days (since Mon May 15 01:53:08 2017)
Network Distance: 1 hop
TCP Sequence Prediction: Difficulty=252 (Good luck!)
IP ID Sequence Generation: All zeros
Service Info: OS: Linux; CPE: cpe:/o:linux:linux_kernel

TRACEROUTE
HOP RTT     ADDRESS
1   0.44 ms dellm6700 (192.168.2.15)

NSE: Script Post-scanning.
Initiating NSE at 01:53
Completed NSE at 01:53, 0.00s elapsed
Initiating NSE at 01:53
Completed NSE at 01:53, 0.00s elapsed
Read data files from: /usr/local/bin/../share/nmap
OS and Service detection performed. Please report any incorrect results at https://nmap.org/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 46.02 seconds
           Raw packets sent: 2075 (95.016KB) | Rcvd: 50 (3.084KB)

How to run ls command case insensitive mode on Linux/Unix

Sometimes you need to use the ls command on your Linux or Unix machine and match the pattern, interpreting upper- and lowercase letters as the same. In other words, I tell ls to find and list files regardless of their case insensitive. For instance, I am going to tell ls command command to ignore the case so that it can match files such as:
ls *service*.pdf
SERVICE.pdf
DELL-Service-M6700.pdf
hp-printer-Service-Manual.pdf

In this quick tip, I explain how to match case insensitive patterns with the ls command on your Linux, macOS, *BSD and Unix-like system.

How to run ls command case insensitive mode on Linux

The ls command currently doesn’t have a case-insensitive match option. However, the workaround is available with various command line options and shell configs to find files in a case insensitive mode using the ls command.

Bash nocaseglob option to match files in a case-insensitive mode

1. Open the terminal application
2. Type the shopt command to enable nocaseglob:
   

shopt -s nocaseglob

Now use the ls command. For example, ignore case distinctions in filenames and match all file cases (upper and lower cases):

ls *pattern*
ls -l *pattern*


ls -l *service*.pdf

Disable the nocaseglob option:

4. shopt -u nocaseglob

When the nocaseglob bash option is set, the ls or any other Linux and Unix command will match filenames in a case-insensitive fashion when performing filename expansion.

ZSH and ls command to list files in case insensitive mode

According to ZSH documentation:

Make globbing (filename generation) sensitive to case. Note that other uses of patterns are always sensitive to case. If the option is unset, the presence of any character which is special to filename generation will cause case-insensitive matching. For example, cvs(/) can match the directory CVS owing to the presence of the globbing flag (unless the option BARE_GLOB_QUAL is unset).

In other words, use the following command on ZSH

unsetopt CAse_glob #<--Make sensitive to file case
ls -l *service*.pdf


setopt CAse_glob #<--Turn it off

Using find command to find files in case-insensitive mode

The find command on Linux, *BSD, and macOS supports finding and listing files using the -iname option. The syntax is:

find /dir/ -iname "*service*.pdf" -ls
OR

find /dir/ -iname "*service*.pdf" -print
The -iname option will match files in case insensitive mode. The -ls option list current file in ls -dils format on screen:

  4456842   5752 -rw-rw-r--   1 vivek    vivek     5888599 Aug 23 14:36 ./SERVICE.pdf
  4456851   6376 -rw-rw-r--   1 vivek    vivek     6527261 Aug 23 14:36 ./hp-printer-Service-Manual.pdf
  4456846  11544 -rw-rw-r--   1 vivek    vivek    11819062 Aug 23 14:36 ./DELL-Service-M6700.pdf

Using ls | grep command to ignore case

The final solution is to use shell pipes. For example, run the ls command and send output to the grep command or egrep command as follows:

ls -l | grep -i "service"
# match service or manual to ignore case distinctions #


ls -l | egrep -i "service|manual"
The -i option is passed to the grep command to perform case insensitive search. The egerp command is used to match either “service” or “manual” words. See about searching multiple words or string pattern using grep/egerp command for more info.

Summing up

This page explained a few options for case-insensitive fashion file listing when performing filename expansion using bash/zsh and standard Unix utilities. However, I strongly suggest that you read the following manual pages using the man command or grep command:

man grep
man bash
man zsh
man find


help shopt 

Bash Built-In Commands

 Many built-in commands exist in Bash to perform different types of tasks. Bash has no built-in function like other programming languages. But the tasks of the built-in functions can be done easily using the different types of built-in commands of Bash. Bash has some special built-in commands and some inherited built-in commands which are inherited from the shell commands. The purposes of the most commonly used built-in commands of Bash and the uses of some built-in commands are described in this tutorial.

List of Some Useful Built-In Commands

 

Command	Purpose
echo	To write the string data in the output.
printf	To write the formatted string data in the output.
read	To take an input from the user.
pwd	To print the absolute path of the current working directory.
date	To print the current date and time of the system.
declare	To declare a variable with the data type.
set	To modify the behavior of the current shell.
unset	To remove any variable and function names.
ls	To print the list of all files and folders of the current location.
cat	To create or read a file.
rm	To remove one or more files.
mkdir	To create a new directory.
rmdir	To remove any directory.
dir	To print the directory stack of the shell.
cd	To change the current directory location.
let	To perform the arithmetic operations.
alias	To create a shortcut of any command.
unalias	To delete any previously created alias command.
return	To return the value from the function.
eval	To evaluate any expression as the command.
history	To print the history information.
export	To pass the shell variable or function from the parent to the child process.
help	To print the help information about built-in shell commands.
exit	To exit to the terminal from the shell with exit status code.

Examples of Some Bash Built-In Commands

The uses of some useful Bash built-in commands are shown in this part of the tutorial.

Example 1: “Ls” Command

Run the following command to print the list of the current files and folders:

$ ls

 
Run the following command to print the list of all files with the “bash” extension:

$ ls *.bash

 
Run the following command to print the list of all files and folders that starts with the “error”:

$ ls error*

 
Output:

The following output appears after executing the previous commands:

Example 2: “Cd” Command

Run the following command to change the current directory location to “/home/fahmida/code”:

$ cd /home/fahmida/code

 
Run the following command to check the content of the changed directory:

$ ls

 
Output:

The following output appears after executing the previous commands:

Example 3: “Cat” Command

Run the following command to create a new file named languages.txt and add some content to the file. Press Ctrl+D to go to the command prompt after adding the content.

$ cat > languages.txt

 
Run the following command to print the content of the file:

$ cat languages.txt

 
Run the following command to append the content to the file:

$ cat >> languages.txt

 
Run the following command to print the content of the file after appending:

$ cat languages.txt

 
Output:

The following output appears after executing the previous commands:

Example 4: “Echo” Command

Run the following command to print a simple string:

$ echo "Welcome to CMHTech"

 
Run the following command to print the string with a newline:

$ echo -e "Welcome\nTo\nCMHTECH"

 
Output:

The following output appears after executing the previous commands:

Example 5: “Read” Command

Run the following command to take the input in the $name variable:

$ read name

 
Run the following command to print the input value:

$ echo $name

 
Run the following command to take the input with the prompt message:

$ read -p 'Enter username:' un

 
Run the following command to print the input value:

$ echo $un

 
Output:

The following output appears after executing the previous commands:

Example 6: “Mkdir” Command

Run the following command to create a directory named “temp”:

$ mkdir temp

 
Run the following command to check whether the directory is created or not:

$ ls

 
Output:

The following output appears after executing the previous commands:

Example 7: “Date” Command

Run the following command to print the current date and time of the system:

$ date

 
Output:

The following output appears after executing the previous command:

Example 8: “Declare” Command

Run the following command to declare a variable named $number of integer type:

$ declare -i number

 
Run the following command to assign the string value to the $number variable that can take only the integer value:

$ number='abc'

 
Run the following command to print the current value of the $number variable which is 0 to assign the string value to the integer variable:

$ echo $number

 
Run the following command to assign the number value to the $number:

$ number=20

 
Run the following command to print the current value of the $number variable:

$ echo $number

 
Output:

The following output appears after executing the previous commands. The output shows that the number variable contains 0 when the string value is assigned to a variable to declare the variable by the “declare” command:

Example 9: “Eval” Command

Run the following command to assign a command to the variable:

$ cmd="echo"

 
Run the following command to assign a string value to a variable:

$ str="Hello World"

 
Run the following command to execute the “echo” command using the “eval” command:

$ eval $cmd $str

 
Output:

The following output appears after executing the previous commands:

Example 10: “History” Command

Run the following command to print the history information of the current terminal:

$ history

 
Output:

The following output appears after executing the previous commands. The output shows that four commands are executed after opening the terminal:

Reverse VLOOKUP in Excel

As we all know there is no way to look up to left for a value using VLOOKUP. But if you switch to INDEX MATCH you can look up in any direction.

 

Calculate the Ratio In Excel

 I have figured out that there are four different ways to calculate the ratio in Excel but using a simple divide method is the easiest one. All you need to do is divide the larger number into the smaller ones and concatenate it with a colon and one and here’s the formula you need to use:

=Larger-Number/Smaller-Number&”:”&”1″

This formula divides the larger number by the smaller one so that you can take the smaller number as a base (1).

Cell Message in Excel

Let’s say you need to add a specific message to a cell, like “Don’t delete the value”, “enter your name” or something like that.

In this case, you can add a cell message for that particular cell. When the user will select that cell, it will show the message you have specified. Here are the steps to do this:

1. First, select the cell to which you want to add a message.
2. After that, go to the Data Tab ➜ Data Tools ➜ Data Validation ➜ Data Validation.
3. In the data validation window, go to the Input Message tab.
4. Enter the title, and message, and make sure to tick mark “Show input message when the cell is selected”.
5. In the end, click OK.

Once the message is shown you can drag and drop it to change its position.