Security scanner for computers and networks.

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108
votes
4answers
326k views

How to find live hosts on my network?

I am trying to find the live hosts on my network using nmap. I am scanning the network in Ubuntu using the command sudo nmap -sP 192.168.2.1/24. However, I am unable to find the live hosts. I just get ...
14
votes
3answers
29k views

How does “traceroute over TCP” work, what are the risks, and how can it be mitigated?

There is a utility called tcptraceroute, and this enhancement called intrace that is used just like a standard traceroute, but it works over TCP. How is the syn flag in TCP used to achieve ...
14
votes
2answers
3k views

Is it possible to identify who's behind a nmap -D scan?

Nmap's -D option stands for decoy, which means that the attacker can simulate that the attack is coming from multiple IPs, including attacker's IP. From the point of view of the victim, is it ...
11
votes
5answers
3k views

Why do hackers scan for open ports?

So, whenever you hear of the mean little hackers who hack websites you hear of "port scanning". I understand what it is (looking for all open ports / services on a remote machine), however that begs ...
11
votes
4answers
4k views

Is my network being sniffed?

Is there any way to find out if someone who is connected to my network is sniffing packets? There is a way with nmap if his card is in promiscuous mode but what if it is passive?
10
votes
4answers
1k views

Filtered ports - What exactly filters them?

By the NMAP definition, unfiltered ports are the ones which cannot be determined to be open or closed since packet filtering prevents its probes from reaching the port. (ISBN 9780979958717 pag. 77) ...
9
votes
4answers
4k views

nmap showing unknown IPs on private network

I had a go at scanning my home network with nmap, doing a 192.168.0.0/16 netscan. To my surprise, the results shown multiple live devices not only on 192.168.1.x (where all our known devices are) but ...
8
votes
4answers
9k views

How to detect hosts running in virtual machines with nmap?

I have to determine if a given subnet has virtual hosts. Are there any ideas about what switches to use?
8
votes
2answers
5k views

How does nmap do a zombie and decoy scan?

We're learning nmap in my ethical hacking class. We got showed how we can use nmap to perform a zombie scan: nmap -PN -sI zombieIP targetIP and decoy scan: nmap -p 135 -D decoyIP targetIP I ...
7
votes
2answers
421 views

What's the advantage of sending an RST packet after getting a response in a SYN scan?

I'm reading about nmap's SYN scan, and it says Nmap sends an RST immediately after the server tries to establish the handshake. My question is - why bother with the RST? Is it to prevent the server ...
7
votes
5answers
32k views

How to bypass tcpwrapped with nmap scan

I'd a scan task and I faced following result Host is up (0.032s latency). Scanned at 2012-10-25 16:06:38 AST for 856s PORT STATE SERVICE VERSION 1/tcp open tcpwrapped 3/tcp open ...
7
votes
6answers
4k views

How to bypass Nmap blockage?

I rent a server, and my provider seems to be blocking nmap. Is there any other tools I could use to test my home network from the outside? Also, does blocking nmap on a network provide any security? ...
7
votes
1answer
1k views

Message signing disabled (dangerous, but default)

Over the last couple of years, I've developed a fairly keen interest in Penetration Testing & Information Security. Throughout this time, I've acquired (and accumulated) a range of different ...
7
votes
1answer
3k views

How to use NMap to portscan a SonicWall that is blocking all attemtps?

It seems that SonicWall is blocking attemtps to scan its ports. I know it has some ports open, like 443, because if I access using the browser I get a web site. But when I try to use NMap I can't see ...
6
votes
3answers
2k views

What are the security issues of open ports?

What could be the threats of having the ports open, after performing a nmap scan and identifying the open ports? I already searched for some answers for this question, but couldn't find anything ...
6
votes
5answers
5k views

Nmap reporting almost every port as open

I have noticed during some assesments when doing a TCP port scan, Nmap will report almost every port as open for a machine. Using for example nmap -sS -PN -T4 target -p0-65535, over 20,000 ports will ...
6
votes
2answers
5k views

Scanning my network with NMAP

Each computer is assigned one ip address on my network, and my ISP supplies one IP for my network. If I try to scan the ip supplied by my ISP what I got is the OS running on the router, running on the ...
6
votes
3answers
984 views

How can I practice using nmap without scanning some real site or performing computer trespass?

I want to learn nmap and its various options. What can I do or setup in order to see examples of issues found by nmap - e.g., something with security holes on purpose.
6
votes
4answers
1k views

Trying to firewall ports 1863, 5190

I'm using Debian's arno-iptables-firewall and I've configured it to only allow access on the ports I need. But nmap shows ports 1863, 5190 open. What gives? How can I interrogate those ports further? ...
6
votes
2answers
872 views

How nmap guesses the operating system?

nmap has the capability to guess the operating system with the option -O. I was highly surprised that it can find the correct kernel or service pack. * How nmap guesses the operating system? * What ...
6
votes
1answer
197 views

What is the purpose of using different DNS server in nmap?

nmap allows the use of different DNS servers (not local). What is the benefit of doing so?
5
votes
3answers
13k views

Why does an nmap -sT scan show ports filtered but -sS shows ports closed

What are possible reasons why an nmap -sT scan would show "ports filtered" but an identical nmap -sS scan shows "ports closed"? I understand that -sT is a full TCP Connect, which is easier to detect (...
5
votes
4answers
2k views

Persisting and comparing NMAP scans

Does anyone have any good recommendations on a good tool for persisting NMAP scans to database? It may be a tool for persisting or simply a java library for easy parsing of the nmap xml scan result ...
5
votes
2answers
991 views

Why would a stealth scan attract more attention than a connect scan?

I'm reading an Information Security book and am faced with the question: Why may nmap stealth scans(SYN) attract more attention than simple connect scans(TCP connect())? Why might it be?
5
votes
2answers
187 views

Stop Nmap scan and preserve XML output

Every time I run Nmap I use the -oA flag. The XML output is an important output item as I feed it into a number of parsers plus Metasploit with db_import. The --resume option can resume a scan but it ...
5
votes
2answers
87 views

Nmap update - SSL/TLS ciper strength indication

Previously with nmap I found it easy to understand the strengths of ciphers noted by the tool (strong, weak...) However this has now changed to a rating of A-F. What does this mean and why did they ...
5
votes
2answers
1k views

Detect what is running on an open port?

I have a wireless camera in my network. Running nmap on the camera, I discovered that the port 1010 is open but I could not find what it is used for. I looked in the administration pannel and did not ...
5
votes
2answers
2k views

How can I use nmap to distinguish between a normal linux machine and an android device?

According to this link: here, nmap 5.2 onwards is now supposed to detect android smartphones. I am using nmap 6.01 but it only identifies android devices as running a linux kernel.
5
votes
1answer
126 views

Nmap doesn't scan the whole range of IPs

I have multiple machines on my home network with a range of private IPs from 10.0.0.0 to 10.255.255.255. When I scan the network, I use: nmap -v 10.0.0.0/8 But the console shows this: Starting ...
5
votes
1answer
7k views

Nmap scan produces all “unknown”

I scanned both localhost, and the IP address of the LAN adapter, and this is the produced output. Starting Nmap 5.51 ( http://nmap.org ) at 2012-10-12 18:06 Eastern Daylight Time Skipping SYN Stealth ...
5
votes
1answer
1k views

Firewalk through a Firewall on our subnet

Having trouble firewalking. I am trying to determine all the open ports on my firewall/gateway. Here is my lab network diagram: (Skip to the bottom of the following explanation for a direct list of ...
5
votes
5answers
2k views

Sharing Nmap scan results in a web page [closed]

Is there a tool that allow the sharing of nmap scan results ? I know nmap can produce XML and I can easily convert them in HTML. I would like to know if there is a tool with more features. For ...
4
votes
5answers
7k views

Increase speed in nmap UDP scan?

How can I get nmap quicker in scanning UDP ports? This kind of scan is incredibly more slow than TCP ports (at least 2-3 times)
4
votes
4answers
1k views

How to run nmap HTTP scripts on unusual ports

How can I make nmap run the HTTP-scripts on ports that are unusual for HTTP, say TCP port 123? On something like nmap -n --script="http* ..." -p123 target nmap does nothing except to check that port ...
4
votes
2answers
12k views

Could Nmap scan switches/routers

Nmap can scan and sometimes successfully detect the running OS in the remote host. However, can nmap scan routers and switches? Most of them use an embedded system.
4
votes
4answers
2k views

How can I scan open ports without being traced back

I would like to scan open ports of a server. But as far as I know, when I try to scan the open ports with something like nmap in shell they would be able to trace me. Is there a way to secure this ...
4
votes
2answers
465 views

Why does a nmap scan give different results depending on whether it's run from inside or outside a LAN

I am testing/setting up a Thompson TG585v7 router/firewall. Results when running nmap from a computer INSIDE the LAN $ sudo nmap -O 210.86.xxx.xxx Starting Nmap 6.40 ( http://nmap.org ) at 2015-...
4
votes
2answers
543 views

If nmap reports a port is open, does that ALSO mean a service is listening on the port?

I have a Thompson TG585v7 router/firewall whose firewall is configured to FORWARD several ports to a computer X54 within the LAN. These ports are in the range 1024 through to 2500 That X54 ...
4
votes
1answer
9k views

How can I see traceroute details in NMAP?

I'm using NMAP for Network scan ; The output does not contain the full traceroute details. Can I view all intermediate routers/hosts using the NMAP GUI? A simple VPN connection IP traceroute... ...
4
votes
3answers
248 views

Nmap showing ISPs router's DNS port in addition to target's ports

Whenever I do nmap scans my ISP router DNS port like the following. This happens for every IP or target. $ nmap -T4 -A -v stackoverflow.com PORT STATE SERVICE VERSION 53/tcp open domain ...
4
votes
2answers
576 views

Determing live hosts past a restrictive firewall with nmap

Sometimes when I am doing an external security assesment, I run into hosts that have the following restrictions/configuration: All ICMP traffic is blocked An IDS or some device returns all ports as ...
4
votes
2answers
63 views

Sorting hosts via open ports using NMap

I was tasked with running a NMap scan against our corporate network and compiling a list of only live endpoints. My issue is how to go about separating out the hosts via their open ports (printer/...
4
votes
1answer
83 views

Armitage check exploit

I am with all fairness not the most experienced penetration tester, I am doing an industry placement where I can improve my skills. I am using Armitage in Kali Linux to check for vulnerabilities in ...
4
votes
2answers
1k views

different results using nmap with/without sudo

What is the reason that after running: $ nmap -sP 192.168.1.0/24 I got 3 results, but running: $ sudo nmap -sP 192.168.1.0/24 shows 7 results. What is the role of using sudo here?
4
votes
2answers
3k views

Why does NMAP scan list hosts as up? [closed]

When running an NMAP scan of my internal network (192.168.1.0/24) from my Mac, NMAP sees all hosts as live. It also believes there is a port 80 http service running on every IP when I do not have 254 ...
4
votes
1answer
67 views

Tracking down rogue wireless device on network

I have an unknown device that is connecting to my wifi router, and can't figure out what it is to save my life. I've never seen it before and haven't bought any new devices lately, it seems to have ...
4
votes
1answer
574 views

Where can I use the TCP FIN scan?

For a coursework i've got to run the various port scans, i'm having trouble with the FIN scan though, I can't seem to find a system where I can try it, everywhere I try it all ports either come back ...
4
votes
1answer
271 views

Is my router/modem compromised?

So I recently ran a port scan (just TCP) on my home router/modem (AT&T U-Verse) and found two peculiar ports that are open. Here is the scan output/results for nmap 192.168.1.254 -P0: Starting ...
3
votes
2answers
878 views

How to force nmap to check all the ports?

I heard that nmap scans for only 1000 most common ports while we do server scan. Is it possible to force nmap to check all the ports for scanning? If yes,How?
3
votes
2answers
4k views

nmap no ping returns host is active and all ports are filtered

I am trying to determine if hosts are up. For hosts where a ping fails, I run a nmap (6.40) Regular and/or Quick scan. For a subset of my hosts, the nmap response is "Host seems down". As a follow up ...