GeekGuy
- Oct 25, 2021
- 6 min read

Top popular NMAP Linux command examples - Part 1

The Nmap aka Network Mapper is an open source and a very versatile tool for Linux system/network administrators. Nmap is used for exploring networks, perform security scans, network audit and finding open ports on remote machine. It scans for Live hosts, Operating systems, packet filters and open ports running on remote hosts.

I’ll be covering most of NMAP usage in two different parts and this is the first part of nmap serious. Here in this setup, I have used two servers without firewall to test the working of the Nmap command.

192.168.100.4 – variant1.airwallet365.com
192.168.100.5 – variant2.airwallet365.com

Nmap command usage

# nmap [Scan Type(s)] [Options] {target specification}

How to Install NMAP in Linux

Most of the today’s Linux distributions like Red Hat, CentOS, Fedoro, Debian and Ubuntu have included Nmap in their default package management repositories called Yum and APT. The both tools are used to install and manage software packages and updates. To install Nmap on distribution specific use the following command.

# yum install nmap		[on Red Hat based systems]
$ sudo apt-get install nmap	[on Debian based systems]

Once you’ve install latest nmap application, you can follow the example instructions provided in this article.

1. Scan a System with Hostname and IP Address

The Nmap tool offers various methods to scan a system. In this example, I am performing a scan using hostname as variant2.airwallet365.com to find out all open ports, services and MAC address on the system.

Scan using Hostname

[root@server1 ~]# nmap variant2.airwallet365.com

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2013-11-11 15:42 EST
Interesting ports on variant2.airwallet365.com (192.168.100.5):
Not shown: 1674 closed ports
PORT     STATE SERVICE
22/tcp   open  ssh
80/tcp   open  http
111/tcp  open  rpcbind
957/tcp  open  unknown
3306/tcp open  mysql
8888/tcp open  sun-answerbook
MAC Address: 08:00:27:D9:8E:D7 (Cadmus Computer Systems)

Nmap finished: 1 IP address (1 host up) scanned in 0.415 seconds
You have new mail in /var/spool/mail/root

Scan using IP Address

[root@server1 ~]# nmap 192.168.100.4

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2013-11-18 11:04 EST
Interesting ports on variant2.airwallet365.com (192.168.100.5):
Not shown: 1674 closed ports
PORT     STATE SERVICE
22/tcp   open  ssh
80/tcp   open  http
111/tcp  open  rpcbind
958/tcp  open  unknown
3306/tcp open  mysql
8888/tcp open  sun-answerbook
MAC Address: 08:00:27:D9:8E:D7 (Cadmus Computer Systems)

Nmap finished: 1 IP address (1 host up) scanned in 0.465 seconds
You have new mail in /var/spool/mail/root

2. Scan using “-v” option

You can see that the below command with “-v” option is giving more detailed information about the remote machine.

[root@server1 ~]# nmap -v variant2.airwallet365.com

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2013-11-11 15:43 EST
Initiating ARP Ping Scan against 192.168.100.5 [1 port] at 15:43
The ARP Ping Scan took 0.01s to scan 1 total hosts.
Initiating SYN Stealth Scan against variant2.airwallet365.com (192.168.0.101) [1680 ports] at 15:43
Discovered open port 22/tcp on 192.168.100.5
Discovered open port 80/tcp on 192.168.100.5
Discovered open port 8888/tcp on 192.168.100.5
Discovered open port 111/tcp on 192.168.100.5
Discovered open port 3306/tcp on 192.168.100.5
Discovered open port 957/tcp on 192.168.100.5
The SYN Stealth Scan took 0.30s to scan 1680 total ports.
Host variant2.airwallet365.com (192.168.100.5) appears to be up ... good.
Interesting ports on variant2.airwallet365.com (192.168.100.5):
Not shown: 1674 closed ports
PORT     STATE SERVICE
22/tcp   open  ssh
80/tcp   open  http
111/tcp  open  rpcbind
957/tcp  open  unknown
3306/tcp open  mysql
8888/tcp open  sun-answerbook
MAC Address: 08:00:27:D9:8E:D7 (Cadmus Computer Systems)

Nmap finished: 1 IP address (1 host up) scanned in 0.485 seconds
               Raw packets sent: 1681 (73.962KB) | Rcvd: 1681 (77.322KB)

3. Scan Multiple Hosts

You can scan multiple hosts by simply writing their IP addresses or hostnames with Nmap.

[root@server1 ~]# nmap 192.168.100.5 192.168.100.6 192.168.100.7

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2013-11-11 16:06 EST
Interesting ports on variant2.airwallet365.com (192.168.100.5):
Not shown: 1674 closed ports
PORT     STATE SERVICE
22/tcp   open  ssh
80/tcp   open  http
111/tcp  open  rpcbind
957/tcp  open  unknown
3306/tcp open  mysql
8888/tcp open  sun-answerbook
MAC Address: 08:00:27:D9:8E:D7 (Cadmus Computer Systems)
Nmap finished: 3 IP addresses (1 host up) scanned in 0.580 seconds

4. Scan a whole Subnet

You can scan a whole subnet or IP range with Nmap by providing * wildcard with it.

[root@server1 ~]# nmap 192.168.100.*

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2013-11-11 16:11 EST
Interesting ports on variant1.airwallet365.com (192.168.100.4):
Not shown: 1677 closed ports
PORT    STATE SERVICE
22/tcp  open  ssh
111/tcp open  rpcbind
851/tcp open  unknown

Interesting ports on variant2.airwallet365.com (192.168.100.5):
Not shown: 1674 closed ports
PORT     STATE SERVICE
22/tcp   open  ssh
80/tcp   open  http
111/tcp  open  rpcbind
957/tcp  open  unknown
3306/tcp open  mysql
8888/tcp open  sun-answerbook
MAC Address: 08:00:27:D9:8E:D7 (Cadmus Computer Systems)

Nmap finished: 256 IP addresses (2 hosts up) scanned in 5.550 seconds
You have new mail in /var/spool/mail/root

On above output you can see that nmap scanned a whole subnet and gave the information about those hosts which are Up in the Network.

5. Scan Multiple Servers using last octet of IP address

You can perform scans on multiple IP address by simple specifying last octet of IP address. For example, here I performing a scan on IP addresses 192.168.100.5, 192.168.100.6 and 192.168.100.7.

[root@server1 ~]# nmap 192.168.100.5,6,7

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2013-11-11 16:09 EST
Interesting ports on variant2.airwallet365.com (192.168.100.5):
Not shown: 1674 closed ports
PORT     STATE SERVICE
22/tcp   open  ssh
80/tcp   open  http
111/tcp  open  rpcbind
957/tcp  open  unknown
3306/tcp open  mysql
8888/tcp open  sun-answerbook
MAC Address: 08:00:27:D9:8E:D7 (Cadmus Computer Systems)

Nmap finished: 3 IP addresses (1 host up) scanned in 0.552 seconds
You have new mail in /var/spool/mail/root

6. Scan list of Hosts from a File

If you have more hosts to scan and all host details are written in a file , you can directly ask nmap to read that file and perform scans. Let’s see how to do that.

Create a text file called “nmaptest.txt” and define all the IP addresses or hostname of the server that you want to do a scan.

[root@server1 ~]# cat > nmaptest.txt

localhost
variant2.airwallet365.com
192.168.100.5

Next, run the following command with “iL” option with nmap command to scan all listed IP address in the file.

[root@server1 ~]# nmap -iL nmaptest.txt

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2013-11-18 10:58 EST
Interesting ports on localhost.localdomain (127.0.0.1):
Not shown: 1675 closed ports
PORT    STATE SERVICE
22/tcp  open  ssh
25/tcp  open  smtp
111/tcp open  rpcbind
631/tcp open  ipp
857/tcp open  unknown

Interesting ports on variant2.airwallet365.com (192.168.100.5):
Not shown: 1674 closed ports
PORT     STATE SERVICE
22/tcp   open  ssh
80/tcp   open  http
111/tcp  open  rpcbind
958/tcp  open  unknown
3306/tcp open  mysql
8888/tcp open  sun-answerbook
MAC Address: 08:00:27:D9:8E:D7 (Cadmus Computer Systems)

Interesting ports on variant2.airwallet365.com (192.168.100.5):
Not shown: 1674 closed ports
PORT     STATE SERVICE
22/tcp   open  ssh
80/tcp   open  http
111/tcp  open  rpcbind
958/tcp  open  unknown
3306/tcp open  mysql
8888/tcp open  sun-answerbook
MAC Address: 08:00:27:D9:8E:D7 (Cadmus Computer Systems)

Nmap finished: 3 IP addresses (3 hosts up) scanned in 2.047 seconds

7. Scan an IP Address Range

You can specify an IP range while performing scan with Nmap.

[root@server1 ~]# nmap 192.168.100.5-16

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2013-11-11 16:09 EST
Interesting ports on variant2.airwallet365.com (192.168.100.5):
Not shown: 1674 closed ports
PORT     STATE SERVICE
22/tcp   open  ssh
80/tcp   open  http
111/tcp  open  rpcbind
957/tcp  open  unknown
3306/tcp open  mysql
8888/tcp open  sun-answerbook
MAC Address: 08:00:27:D9:8E:D7 (Cadmus Computer Systems)

Nmap finished: 10 IP addresses (1 host up) scanned in 0.542 seconds

8. Scan Network Excluding Remote Hosts

You can exclude some hosts while performing a full network scan or when you are scanning with wildcards with “–exclude” option.

[root@server1 ~]# nmap 192.168.100.* --exclude 192.168.100.4

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2013-11-11 16:16 EST
Interesting ports on variant2.airwallet365.com (192.168.100.5):
Not shown: 1674 closed ports
PORT     STATE SERVICE
22/tcp   open  ssh
80/tcp   open  http
111/tcp  open  rpcbind
957/tcp  open  unknown
3306/tcp open  mysql
8888/tcp open  sun-answerbook
MAC Address: 08:00:27:D9:8E:D7 (Cadmus Computer Systems)

Nmap finished: 255 IP addresses (1 host up) scanned in 5.313 seconds
You have new mail in /var/spool/mail/root

9. Scan OS information and Traceroute

With Nmap, you can detect which OS and version is running on the remote host. To enable OS & version detection, script scanning and traceroute, we can use “-A” option with NMAP.

[root@server1 ~]# nmap -A 192.168.100.5

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2013-11-11 16:25 EST
Interesting ports on variant2.airwallet365.com (192.168.100.5):
Not shown: 1674 closed ports
PORT     STATE SERVICE VERSION
22/tcp   open  ssh     OpenSSH 4.3 (protocol 2.0)
80/tcp   open  http    Apache httpd 2.2.3 ((CentOS))
111/tcp  open  rpcbind  2 (rpc #100000)
957/tcp  open  status   1 (rpc #100024)
3306/tcp open  mysql   MySQL (unauthorized)
8888/tcp open  http    lighttpd 1.4.32
MAC Address: 08:00:27:D9:8E:D7 (Cadmus Computer Systems)

No exact OS matches for host (If you know what OS is running on it, see http://www.insecure.org/cgi-bin/nmap-submit.cgi).

TCP/IP fingerprint:
    SInfo(V=4.11%P=i686-redhat-linux-gnu%D=11/11%Tm=52814B66%O=22%C=1%M=080027)
    TSeq(Class=TR%IPID=Z%TS=1000HZ)
    T1(Resp=Y%DF=Y%W=16A0%ACK=S++%Flags=AS%Ops=MNNTNW)
    T2(Resp=N)
    T3(Resp=Y%DF=Y%W=16A0%ACK=S++%Flags=AS%Ops=MNNTNW)
    T4(Resp=Y%DF=Y%W=0%ACK=O%Flags=R%Ops=)
    T5(Resp=Y%DF=Y%W=0%ACK=S++%Flags=AR%Ops=)
    T6(Resp=Y%DF=Y%W=0%ACK=O%Flags=R%Ops=)
    T7(Resp=Y%DF=Y%W=0%ACK=S++%Flags=AR%Ops=)
        PU(Resp=Y%DF=N%TOS=C0%IPLEN=164%RIPTL=148%RID=E%RIPCK=E%UCK=E%ULEN=134%DAT=E)

Uptime 0.169 days (since Mon Nov 11 12:22:15 2013)

Nmap finished: 1 IP address (1 host up) scanned in 22.271 seconds
You have new mail in /var/spool/mail/root

In above Output, you can see that nmap is came up with TCP/IP fingerprint of the OS running on remote hosts and being more specific about the port and services running on the remote hosts.

10. Enable OS Detection with Nmap

Use the option “-O” and “-osscan-guess” also helps to discover OS information.

[root@server1 ~]# nmap -O variant2.airwallet365.com

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2013-11-11 17:40 EST
Interesting ports on variant2.airwallet365.com (192.168.100.5):
Not shown: 1674 closed ports
PORT     STATE SERVICE
22/tcp   open  ssh
80/tcp   open  http
111/tcp  open  rpcbind
957/tcp  open  unknown
3306/tcp open  mysql
8888/tcp open  sun-answerbook
MAC Address: 08:00:27:D9:8E:D7 (Cadmus Computer Systems)
No exact OS matches for host (If you know what OS is running on it, see http://www.insecure.org/cgi-bin/nmap-submit.cgi).
TCP/IP fingerprint:
SInfo(V=4.11%P=i686-redhat-linux-gnu%D=11/11%Tm=52815CF4%O=22%C=1%M=080027)
TSeq(Class=TR%IPID=Z%TS=1000HZ)
T1(Resp=Y%DF=Y%W=16A0%ACK=S++%Flags=AS%Ops=MNNTNW)
T2(Resp=N)
T3(Resp=Y%DF=Y%W=16A0%ACK=S++%Flags=AS%Ops=MNNTNW)
T4(Resp=Y%DF=Y%W=0%ACK=O%Flags=Option -O and -osscan-guess also helps to discover OS
R%Ops=)
T5(Resp=Y%DF=Y%W=0%ACK=S++%Flags=AR%Ops=)
T6(Resp=Y%DF=Y%W=0%ACK=O%Flags=R%Ops=)
T7(Resp=Y%DF=Y%W=0%ACK=S++%Flags=AR%Ops=)
PU(Resp=Y%DF=N%TOS=C0%IPLEN=164%RIPTL=148%RID=E%RIPCK=E%UCK=E%ULEN=134%DAT=E)

Uptime 0.221 days (since Mon Nov 11 12:22:16 2013)

Nmap finished: 1 IP address (1 host up) scanned in 11.064 seconds
You have new mail in /var/spool/mail/root

We will continue with part 2 here.