Nmap Scan with Timing Parameters

Hello everyone, in this article we will have a look at the different parameters that are used together to make a timing template and how to use those parameters individually according to will.

Let’s Start!!

Nmap timing template

As we have seen that Nmap has multiple timing templates that can be used for differently as according to the requirement. Click here to check the timing scan article. Let’s see what’s inside the timing template. For getting the description of timing template we’ll use -dattribute.

Here we have multiple arguments that collectively make a timing template. Let’s have a look at them one by one.

  • Host-groups
  • Rtt-timeouts
  • Scan-delay
  • Max-retires
  • Min-rates
  • Parallelism

Maximum Retries (–max-retries)

–max-retries specifies the number of times a packet is to be resent on a port to check if it is open or closed. If –max-retries is set to 0, the packets will be sent only once on a port and no retries will be done.

Here in wireshark, we can see that 1-1 TCP SYN packet sent to each port from source: 192.168.1.126 to destination: 192.168.1.139 are not sent again.

Now we will apply a small firewall rule on the target machine so that the packets get blocked if they come at a faster rate.

Now, the normal scan will not show any results with max-retries

As we can see that the ports whose packets got dropped are not sent again so their status is not determined.

here we can increase the max-retries value which will bypass the specified firewall filter so that we can get the exact port status.

Here we can see that TCP SYN packets sent to one port from source: 192.168.1.126 to destination: 192.168.1.139 are sent again and again until the packets return a specified reply or the maximum retry value (here 5) is reached.

Host-timeout

The –host-timeout is an attribute that specifies the scan to give up on a host after the specified time. The lesser the time specified the more are the chances of inaccuracy in scan results.

We can specify time in milliseconds (ms), seconds (s), minutes (m)

Now we will try to get the result by increasing the timeout value

We can use –host-timeout in other scenarios also like when we need to check if the host system is live or not. Here we have shown how the host-timeout can affect the results of a ping scan.

Output from above command had given 0 host is up.

Output from above command had given 1 host is up.

Hostgroup

hostgroup attribute is specified to scan a specified number of hosts in network at a time. You need to specify minimum number of hosts or maximum number of hosts or both to be scaned at a time

From given below image you can observed that it has shown only 3 live host from inside complete subnet mask and save your time from scanning complete network.

Scan delay

Scan delay is used to delay the packet to be sent by the specified time. It is very useful in evading time based firewalls.

here we can see the time difference in between the packets

packet 1: TCP SYN packet on port 25 at 07:58:01 from 192.168.1.126 to 192.168.1.139

packet 2: TCP SYN packet on port 22 at 07:58:12 from 192.168.1.126 to 192.168.1.139

Now if you will count the time difference between these packets you get 11 sec time laps between these two packets.

Maximum rate (max-rate)

Rate is an attribute that specifies at what rate is the packets are to be sent, in other words number of packets to be sent at a time. Max-rate specifies maximum number of packets to be sent at once.

wireshark shows that the packets sending rate is less than 2, means number of packets sent at a time is less than or equal to 2

packet 1: TCP SYN packet on port 21 at 03:17:20 from 192.168.1.126 to 192.168.1.139

packet 2: TCP SYN packet on port 23 at 03:17:21 from 192.168.1.126 to 192.168.1.139

Now if you will count the time difference between these packets you get 1 sec time laps between these two packets indicating that these two packets were not sent together.

Minimum rate (mini-rate)

Min-rate specifies maximum number of packets to be sent at once. Here if we want atleat 2 packet must be sent on target’s network at same time not less then this, then need to execute below command.

wireshark shows that the packets sending rate is greater than 2, means number of packets sent at a time is equal to or greater than 2

packet 1: TCP SYN packet on port 23 at 03:28:29 from 192.168.1.126 to 192.168.1.139

packet 2: TCP SYN packet on port 22 at 03:28:29 from 192.168.1.126 to 192.168.1.139

Now if you will count the time difference between these packets you get only a fraction of second as time laps between these two packets indicating that these two packets were sent together.

Parallelism

Parallelism attribute is used to send multiple packets in parallel, min-parallelism means that the number of packets to be sent in parallel is to be greater than the value specified and max-parallelism means that the number of packets to be sent in parallel is to be less than or equal to the value specified

In wireshark we can see the couple of TCP-SYN packetssent in parallel from 192.168.1.126 which is neither less nor greater than 2.

Round trip timeout

Rtt timeout is the time specified for a packet to return a reply, min-rtt-timeout specifies the minimum value of time that is to be taken by a packet to return a reply

wireshark shows that the packet and its reply takes time greater than the min-rtt-timeout specified

packet 1: TCP SYN packet on port 25 at 08:10:53.232666116 from 192.168.1.126 to 192.168.1.139

packet 2: SYN ACK packet from port 25 at 08:10:53.233466679 from 192.168.1.139 to 192.168.1.126

Max-rtt-timeout

max-rtt-timeout specifies the maximum value of time that is to be taken by a packet to return a reply

wireshark shows that the packet and its reply takes time lesser than the max-rtt-timeout

packet 1: TCP SYN packet on port 22 at 08:15:08.171777907 from 192.168.1.126 to 192.168.1.139

packet 2: SYN ACK packet from port 22 at 08:15:08.173117154 from 192.168.1.139 to 192.168.1.126

Intial Round trip timeout

Initial-rtt-timeout specifies the initial value of time to be taken by a packet to return a reply, the return time can be greater or lesser than the  initial-rtt-timeout because of the max-rtt-timeout and min-rtt-timeout specifeies the range of time for a packet to return a reply but the packet attempts to return a reply in the time specified in initial-rtt-timeout

wireshark shows that the time taken by packet to return reply is around same as specified in initial-rtt-timeout

packet 1: TCP SYN packet on port 23 at 08:18:45.342395520 from 192.168.1.126 to 192.168.1.139

packet 2: SYN ACK packet from port 23 at 08:18:45.342930962 from 192.168.1.139 to 192.168.1.126

Auhtor:  Deepanshu is a Certified Ethical Hacker and a budding Security researcher. Contact here.

Generating Scan Reports Using Nmap (Output Scan)

Hello friends, several times you might have used NMAP to performing Network scanning for enumerating active Port services of target machine but there are sometimes where we want to save the nmap scan. Nmap output scan is used to save the result of nmap scan in different formats.

Let’s Begin

Requirement

Attacker: Kali Linux

Target’s IP: 192.168.1.113

Normal Output Format

-oN <filespec> (normal output)

Nmap supports different formats for saving scan results. Depending on your needs, you can choose between a normal, XML, and grepable output. Normal mode saves the output as you see it on your screen, minus the runtime debugging information. This mode presents the findings in a well structured and easy-to-understand manner.

Now the scan is saved on desktop and we can access it using cat or text editor.

cat Desktop/nmap

XML Output Format

-oX <filespec> (XML output)

XML stands for Extensible Markup Language is a usually known, tree-structured file format supported by Nmap.To save the scan results to a file in the XML format; add the option -oX <filename>, as shown in the following command:

Nmap also consist of additional debugging information when you save the scan results in this format.

An XML file, when generated, will contain the following information:

  • Host and port states
  • Services
  • Timestamps
  • Executed command
  • Nmap Scripting Engine output
  • Run statistics and debugging information

You can view the output in Gedit, It will look as shown below

We can also convert the Nmap scan which we saved in the xml format earlier to a portable html format using the given command:

xsltproc Desktop/nmap.xml –o nmap.html

Now open the nmap.html file in your favourite browser. Here is a screenshot depicting the converted html report. As you can see that it is very simply formatted and Easy to Read and Understand.

Script kiddie output

 -oS <filespec> (ScRipT KIdd|3 oUTpuT)

Script kiddie output is like interactive output, except that it is post-processed to better suit the l33t HaXXorZ, this option was made to make fun of script kiddies.

Now we can see that the file is saved on desktop which is as similar as normal scan output result.

cat Desktop/nmap

Grepable Output Format

 -oG <filespec> (grepable output)

 The grepable format was included to help users extract information from logs without having to write a parser, as this format is meant to be read/parsed with standard UNIX tools. To save the scan results to a file in the grepable format, add the option -oG <filename>, as shown in the following command:

In grepable mode, each host is placed on the same line with the format <field name>:

<value>,and each field is separated by tabs (\t). The number of fields depends on what

Nmap options were used for the scan.

There are eight possible output fields:

  • Host: This field is always included, and it consists of the IP address and reverse DNS name if available
  • Status: This field has three possible values—Up, Down, or Unknown
  • Ports: In this field, port entries are separated by a comma and a space character, and each entry is divided into seven fields by forward slash characters (/)
  • Protocols: This field is shown when an IP protocol (-sO) scan is used
  • Ignored: This field shows the number of port states that were ignored
  • OS: This field is only shown if OS detection (-O) was used
  • Seq Index: This field is only shown if OS detection (-O) was used
  • IP ID Seq: This field is only shown if OS detection (-O) was used

cat Desktop/nmap

Saving Output in ALL Format

 -oA <basename> (Output to all formats)

Nmap supports the alias option -oA <basename>, which saves the scan results in all of the available formats—normal, XML, and grepable. The different files will be generated with the extensions .nmap, .xml, and .gnmap

Now we check the directory and find all the 3 types of file available to us.

Author: Sayantan Bera is a technical writer at hacking articles and cyber security enthusiast. Contact Here

Understanding Guide for Nmap Timing Scan (Firewall Bypass)

In this article we are going to scan the target machine with normal Nmap scan along with Timing template and the time between packets can be confirmed by analysis of Nmap traffic through Wireshark.

Timing template in nmap is defined by –T<0-5> having -T0 as the slowest and –T5 as the fastest. By default all nmap scans run on –T3 timing template. Timing template in Nmap is used to optimize and improve the quality and performance of scan to get desired results.

Let’s start!!

Nmap Insane (-T5) Scan

This template is used for sending packets insanely fast and waits only 0.3 seconds for response. The time difference between two packets sent is upto 5 milliseconds. This timing template makes the scan superfast but the accuracy is sacrificed sometimes. Nmap gives-up on a host if it couldn’t complete the scan within 15 minutes. Other than that, -T5 should be used only on fast network and high end systems as sending packets this fast can affect the working of the network or system and can result into system failure.

For using timing template use the attribute –T<0-5> after Nmap while scanning a target network

Here are the packets sent to the target IP are sent by a maximum difference of 5 milliseconds or 0.005 seconds

Packet 1 has Arrival Time of 04:41:04.557153433

Packet 2 has Arrival Time of 04:41:04.557225304

The difference between the arrival time of Packet 1 and Packet 2 is about 0.07 milliseconds.

Nmap Aggressive (-T4) Scan

This template is used for sending packets very fast and waits only 1.25 seconds for response. The time difference between two packets sent is upto 10 milliseconds. Nmap official documentation recommends using –T4 for “reasonably modern and reliable networks”.

Here are the packets sent to the target IP are sent by a maximum difference of 5 milliseconds or 0.005 seconds

Packet 1 has Arrival Time of 05:58:34.636899267

Packet 2 has Arrival Time of 05:58:34.637122896

The difference between the arrival time of Packet 1 and Packet 2 is about 0.2 milliseconds.

Nmap Normal (-T3) Scan

This is the default nmap timing template which is used when -T argument is not specified.

Packet 1 has Arrival Time of 06:01:12.574866212

Packet 1 has Arrival Time of 06:01:12.575059033

The difference between the arrival time of Packet 1 and Packet 2 is about 0.1 milliseconds.

Nmap Polite (-T2) Scan

This template is used for sending packets quickly then –T0 and –T1 but still slower than normal scan. The time difference between two packets sent is 0.4 seconds.

Packet 1 has Arrival Time of 06:07:38.139876513

Packet 2 has Arrival Time of 06:01:12.540686453

Nmap Sneaky (-T1) Scan

This template is used for sending packets quickly but still slower than normal scan. The time difference between two packets sent is 15 seconds.

Packet 1 has Arrival Time of 06:17:02.354879724

Packet 2 has Arrival Time of 06:17:17.371063606

The difference between the arrival time of Packet 1 and Packet 2 is about 15 seconds.

Nmap Paranoid (-T0) Scan

This template is used for sending packets very slowly as only one port is scanned at a time. The time difference between two packets sent is 5 minutes.

Packet 1 has Arrival Time of 06:32:25.043303267

Packet 2 has Arrival Time of 06:37:25.080804929

The difference between the arrival time of Packet 1 and Packet 2 is about 5 minutes.

Evading Time Based Firewall rules using timing templates

Block Insane T5 scan

Even though we can speed up the scan by –T5 and –T4 templates, there are chances that the target system is using some kind of firewall rules to secure itself. Here are some examples of the firewall rules and methods to bypass them.

This rule will block tcp packets from an IP address if the packet count goes more than 1. In other words only first packet will be responded from an IP address in 1 second.

If you’re scanning more than 1 port on a target system having above rule, the result will not be as desired. Like if we use -T5 or -T4 in nmap scan, the time difference between packets is very much less than 1 second so if we scan five ports at a time it will show one as open/closed and others as filtered. But -T5 has also –max-retries set to 2 means it will retry to get reply from ports 2 more times hence there will be 3 out 5 ports with accurate open/close status and the rest 2 with filtered status

From given below image you can observe that it has shown 3 ports are open and 2 ports are filtered.

The packet transfer between the target and the victim is captured through wireshark, it clearly shows that the TCP SYN packets are send multiple times on ports 22 and 23 and didn’t received any reply packet for those request packet.

Bypass Insane T5 Firewall filter

1st method

Use –max-retries argument to increase the –max-retries value so that each retry gives accurate status of one port at a time. Execute given below command for increasing maximum retries with T5 scan here I had 4 you can modify it as per your requirement.

now if you notice from given below image you can observe that it has shown all 5ports are open.

Here, the packet transfer shows that in each retry one different port sends the reply in order to confirm its statusas shown in given below image.

2nd Method

The second method is to use a timing template which has a greater time difference between packets, like here we can use time template below T5 i.e. from T4 to T0 to bypass above rule.

nmap -T4 -p21-25 192.168.1.104

or

nmap -T3 -p21-25 192.168.1.104

or

nmap -T2 -p21-25 192.168.1.104

or

nmap -T1 -p21-25 192.168.1.104

or

nmap -T0 -p21-25 192.168.1.104

Here, the packet transfer shows that each port has sent the reply but first reply was instantly and other ports replied one by one after some time.

Block Aggressive T4, Normal T3 & Polite T2 Scan

Now given below rules will block tcp packets from an IP address if the packet count goes more than 1. In other words only first packet will be responded from an IP address in 3 seconds.

Here we are using -T4 for scanning 5 ports, the time difference between packets is very much less than 1 second so if we scan five ports at a time it will show one as open/closed and others as filtered. But –T4 has also –max-retries set to 6 means it will retry to get reply from ports 6 more times but as the time limit exceeds the total time taken by all retries it will show all ports filtered

nmap -T4 -p21-25 192.168.1.104

or

nmap -T3 -p21-25 192.168.1.104

or

nmap -T2 -p21-25 192.168.1.104

or

Result of T4, T3, and T2 scan can be as either all port will be filtered or any one port can show open/close state. From given below image you can observe that it has shown all 5 ports are filtered.

Here we can see that none of the packets got reply

Bypass Aggressive T4, Normal T3 & Polite T2 Firewall filter

To bypass this kind of rule we have to use a Timing Template which is slower than -T4

Here we can see that all the packets got reply because time interval in T1 is almost 15 seconds.

Block Sneaky (-T1) Scan

Now this rule is to block tcp packets from an IP address if the packet count goes more than 1. In other words only first packet will be responded from an IP address in 200 seconds.

Now repeat the T1 scan again as given below and this time you will found that firewall is blocking our Nmap probes for identify open/close state of any port.

Results of T1 scan can be as either all port will be filtered or any one port can show open/close state. From given below image you can observe that it has shown all 4 ports are filtered.

Here we can see that only one of the packets got reply rest are drop by firewall.

Bypass Sneaky (-T1) Scan

To bypass this kind of rule we have to use a Timing Template which has time difference in packets for more than 200 seconds, therefore use paranoid time scan because time difference between two packets is near about 5 mints as discussed above.

From given below image you can observe that it has taken 1813.61 sec which is close to 30 mints for scanning 5 ports and found open state for all 5 ports.

Here we can see that we have got response of every packet even though the firewall had the security rules set.

To evade any type of IPS or Firewall, you need to remember that it will take much longer time than usual to scan the target system using slower timing template so try to specify a small number of ports so that the slower scans doesn’t take time to scan the ports that you don’t intended to.

Auhtor:  Deepanshu is a Certified Ethical Hacker and a budding Security researcher. Contact here.

Understanding Guide for Nmap Ping Scan (Firewall Bypass)

In this article we are going to scan the target machine with different Nmap ping scans and the response packets of different scans can be confirmed by analysis of Nmap traffic through Wireshark.

Ping scan in nmap is done to check if the target host is alive or not. As we know that ping by default send the ICMP echo request and gets an ICMP echo reply if the system is alive. Ping scan by default send an ARP packet and gets a response to check if the host is up.

Nmap scans changes their behavior according to the network they are scanning.

  • Scanning Local Network with Nmap where nmap sends an ARP packet with every scan
  • If an external network is to be scanned; Nmap sends following request packets:
  1. ICMP echo request
  2. ICMP timestamp request
  3. TCP SYN to port 443
  4. TCP ACK to port 80

In this article we are using —disable-arp-ping attribute for changing the behavior of nmap scans to treat a local network as an public network.

Let’s Start!!

Ping Sweep

In order to identify live host without using ARP request packet Nmap utilize –sP option which is known as Ping Sweep Scan. We can use –sn flag which mean no port scan also know as ping scan.

From given below image you can observe it found 1 Host is up. Since we have disables Arp request packet for local network scans by using parameter –disable-arp-ping therefore here it will treat it as an external network and behave accordingly that as discussed above.

Demonstrating working of Ping Sweep using wireshark

From given below image you can observer following packet of request and reply between both network IP

  1. ICMP echo request
  2. TCP SYN to port 443
  3. TCP ACK to port 80
  4. ICMP timestamp request
  5. ICMP echo reply
  6. TCP RST, ACK to port 443
  7. TCP RST to port 80
  8. ICMP timestamp Reply

Block Ping Sweep Scan

Now let’s put some firewall rules in IPTABLES to drop ICMP packets, TCP SYN packets on port 443 and TCP ACK on port 80 which will block Ping Sweep scan

Now repeat again ping sweep scan for identifying state of live host. From given below image you can observe this time it shows that 0 host is up which means firewall has blocked packets send by this scan.

Again demonstrating request packets of Ping Sweep scan with wireshark and if you notice given below image then you will found that this time it has not received any reply packet.

Bypass Ping Sweep Filter using TCP SYN Ping

Now, we’ll try to bypass the firewall rules by using ping scan with TCP SYN packets, for that we’ll use –PS attribute. –PS sends TCP SYN packet on port 80 by default; we can change it by specifying the ports with it, like: -PS443.

From given below image you can observe that observe it found 1 Host is up.

From given below image you can observe that it is showing result which similar to NMAP stealth scan. Here it is following TCP Half connection mechanism where SYN packet is send on port 80 and received SYN, ACK from port 80 and then RST packet for reset connection

The difference between –sP packet on port 80 and –PS packet on port 80 is as following:

  • Ping sweep scan [-sp] send TCP ACK packet on port 80 and hex value of ACK flag is 10, as reply from host machine it receives RST packet whose hex value is 4.
  • TCP SYN Ping scan send TCP SYN packet on port 80 and its hex value is 2, as reply it received SYN, ACK packet whose value is sum of their hex value i.e. 2 + 10 = 12 and able to bypass above firewall rule applied on port 80 for TCK ACK packet.

Block TCP SYN Ping Scan

Sometimes network admin apply filter as given below using Iptables on TCP SYN packet to drop all SYN packet to initiate TCP connection with all TCP Port in their network.

As result it block the NMAP TCP SYN Ping probes so that it could not identify state of live host.

Now repeat again TCP SYN Ping for identifying state of live host. From given below image you can observe this time it shows that 0 host is up which means firewall has blocked packets send by this scan.

Bypass TCP SYN Ping using TCP ACK Ping

In order to bypass this, we’ll use ping scan using TCP ACK packets, for that we’ll use –PA attribute. –PA sends TCP ACK packet on port 80 by default, we can change it by specifying the ports with it, like: -PA443

From given below image you can observe that observe it found 1 Host is up.

When you will notice given below packets captured by wireshark you will found that here ACK packet is sent on port 80 as reply received RST packet from port 80.

Block TCP ACK Ping Scan

Sometimes network admin apply filter as given below using Iptables on TCP ACK packet to drop all ACK packet to established TCP connection with all TCP Port in their network.

As result it block the NMAP TCP ACK Ping probes so that it could not identify state of live host.

Now repeat again TCP ACK Ping for identifying state of live host. From given below image you can observe this time it shows that 0 host is up which means firewall has blocked packets send by this scan.

Bypass TCP ACK Ping using ICMP Echo

In some scenario network admin apply firewall filter on TCP flag to resist unwanted TCP communication in network, here let’s consider that network admin had blocked TCP communication by applying filter on SYN as well on ACK flag.

In order to bypass this rule we’ll use ping scan with ICMP packets, for that we’ll use –PE attribute. –PE sends ICMP echo request packet [ICMP type 8] and received ICMP echo reply packet [ICMP type 0].

From given below image you can observe that observe it found 1 Host is up.

Block ICMP Echo Ping Scan

Usually most of network admin apply ICMP filter on their network so that other system or network cannot able to Ping their network.

As result it block the NMAP ICMP echo Ping probes so that it could not identify state of live host.

Now repeat again TCP ICMP Ping for identifying state of live host. From given below image you can observe this time it shows that 0 host is up which means firewall has blocked packets send by this scan.

Demonstrating NMAP ICMP echo Ping with wireshark shows only ICMP request packet in network and didn’t received any reply packet from host network as shown in given below image.

Bypass ICMP Echo Ping using ICMP Timestamp Ping

In order to bypass this rule we’ll use ping scan with ICMP packets, for that we’ll use –PP attribute. –PP sends ICMP timestamp request packet [ICMP type 13] and received ICMP timestamp reply packet [ICMP type 14].

From given below image you can observe that observe it found 1 Host is up.

Demonstrating NMAP ICMP timestamp Ping with wireshark shows ICMP timestamp request packet send  in network and  received any timestamp reply packet from host network as shown in given below image.

Block ICMP Ping Scan

It might be possible that network admin had block entire types ICMP message by dropping all ICMP packets using following iptables filter.

As result it block the NMAP ICMP Ping probes so that it could not identify state of live host.

Now repeat again ICMP Ping either –PP or PE for identifying state of live host. From given below image you can observe this time it shows that 0 host is up which means firewall has blocked packets send by this scan.

Bypass ICMP Ping Scan using UDP Ping

We have seen multiple ways to check if the system is live. Now, you can determine whether a system is up or not whether it is on local network or public network.

We had observed that ping scan with ICMP ping is not working or even if TCP packet filter is also enabled in host network then it become difficult to identify live host, now to bypass such types of rule we’ll use ping scan with UDP packets, for that we’ll use –PU attribute.

 –PU sends UDP packet when no ports are specified, the default is 40125, as reply received ICMP message such as “ICMP destination unreachable” which means host is live.

From given below image you can observe that observe it found 1 Host is up.

Demonstrating NMAP UDP Ping with wireshark shows UDP request packet send on 40125 in network and  received ICMP destination unreachable as reply packet from host network as shown in given below image.

Block UDP and Ping Sweep

Now let’s put some firewall rules in IPTABLES to drop ICMP packets, TCP SYN packets on port 443 and TCP ACK on port 80 which will block Ping Sweep scan as well as Drop UDP packet. Might be network admin had blocked entire TCP packet.

As result it will resist NMAP for making TCP Ping, ICMP Ping and UDP ping so that it could not identify state of live host.

Now repeat again UDP Ping for identifying state of live host. From given below image you can observe this time it shows that 0 host is up which means firewall has blocked packets send by this scan.

Bypass UDP and Ping Sweep using Protocol Scan

Using Protocol Ping scan we can identify live host when ICMP, TCP and UDP has been blocked, for that we’ll use –PO attribute. –PO sends IP packet with the particular protocol number place in their IP header, If no protocols are precise, the default is to send multiple IP packets for ICMP (protocol 1), IGMP (protocol 2), and IP-in-IP (protocol 4).

From given below image you can observe that observe it found 1 Host is up.

From given below image of wireshark we can observe the following mechanism followed by Protocol ping scan.

  • Send ICMP Echo to host network
  • Send IGMP query to host network
  • Send IPv4 (IP-in-IP) to host network
  • Received ICMP Destination unreachable as reply from Host

Block IP Protocol Ping Scan

Now let’s put some firewall rules in IPTABLES to drop ICMP packets, TCP SYN packets on port 443 and TCP ACK on port 80 which will block Ping Sweep scan as well as Drop UDP packet and IP protocol too in network to prevent the network from any kind of Ping scan. Might be network admin had blocked entire TCP packet.

As result it will resist NMAP for making TCP Ping, ICMP Ping, UDP ping and Protocol ping so that it could not identify state of live host.

Now repeat again Protocol Ping for identifying state of live host. From given below image you can observe this time it shows that 0 host is up which means firewall has blocked packets send by this scan.

Bypass IP protocol Ping using No Ping Scan

Now when above all Ping scan get failed to identify state of Host is up or down then we choose the last and best option “No Ping” for we will use –PN/-P0/-Pn and basically perform TCP port scan for top 1000 ports.

 If you want to prevent Port scan and ping scan use sweep ping with no ping as given below to identify state of host is up or down.

From given below image you can observe that observe it found 1 Host is up.

Auhtor:  Deepanshu is a Certified Ethical Hacker and a budding Security researcher. Contact here.

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