Nmap (Network Mapper) is a security scanner originally written by Gordon Lyon (also known by his pseudonym Fyodor Vaskovich) used to discover hosts and services on a computer network, thus creating a "map" of the network.

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nmap shows strange open ports

Running nmap on my localhost shows me strange open ports: $ nmap -p- localhost Starting Nmap 6.47 ( http://nmap.org ) at 2015-12-28 12:14 CET Nmap scan report for localhost (127.0.0.1) Host is up ...
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32 views

getting a list of live assets using nmap and script?

I'm playing around with a way to find all network assets from the command line that will return an IP, a hostname, and then have a way to see all interfaces associated with that host. I was using ...
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2answers
83 views

Port-scanning on Cisco router with Nmap

I have Cisco 2911 router just booted with factory settings and no ACLs or NAT configured. All I did is turned on the interfaces and assigned IPs. I am trying to scan for open ports with Nmap, but the ...
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23 views

Azure NAT blocking connections

When I try to connect to a port on the public IP address of a node, 50% of the time Azure doesn't respond and nmap marks it as "filtered". When I try to connect to the same port from the node using ...
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1answer
30 views

cant scan and ping my ip from outside

when I scan my network using nmap it gives me something like this #nmap -vv -Pn -sV -sT -p80 -oG - 116.135.*.* # Ports scanned: TCP(1;80) UDP(0;) SCTP(0;) PROTOCOLS(0;) Host: 116.135.*.* () ...
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37 views

“Filtered” port when accessing server

I'm having periodic trouble accessing one of my DigitalOcean servers from Azure machines. I have isolated a test that - I believe - demonstrates the issue and captured a tcpdump from the server for ...
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2answers
56 views

Run ncat in background

from some time I'm trying to resolve very annoying issue: I need to have simple server which will listen on particular TCP port and throw all information which it recieve to trash. I'm doing it by ...
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57 views

Why nmap result is different from online port scanner result?

I have a vps A, and I am running smtp on it. If I run nmap from my local desktop to scan for my vps it turns out that port 25 (smtp) is filtered. However, if I run online scanner (fill my vps's IP ...
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1answer
17 views

NMAP not mapping DOWN status

I used this command from another post and the file scan.txt only shows the servers with UP status. The listing should also show down status of IP. Is there a switch for that? nmap -sn -PE -oG ...
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1answer
163 views

NMAP (or other) continuous port scan until it returns open?

Is there a way with nmap or anything else to do a continuous port scan, say on port 22, until the service comes up and the port is coming back as open? Kind of like you may have an infinite ping ...
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2answers
118 views

Is there a reliable way to detect OS of the network hosts from linux workstation?

How to detect OS of running computers on the network. We use linux. I want to write wrapper on the python, which will periodically scan network and write results to google spreadsheet. I tried nmap ...
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88 views

Port 80 filtered nmap

Suddenly my server's port 80 is shown as filtered (no server changes are made). My sites are sometimes timing out or stays in waiting for a very long time (in browser). My 1&1 tech support is of ...
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82 views

NMAP port scanning - inconsistent results

I ran the same nmap commands subsequently, and got two sets of results. I know that there are three open ports, but on each run, only two are shown. Can anyone explain these results? ...
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2answers
61 views

I cant open a port iptables - The command runs, but port keeps closed [closed]

I want to make a simple redirect of my notebook port to a VM port (in my notebook also).. iptables -I INPUT -p tcp --dport 2424 -j ACCEPT iptables -t nat -A PREROUTING -p tcp --dport 2424 -j DNAT ...
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1answer
204 views

How to interpret nmap result, host up but no ports open

I have used nmap to map a network, scanning using the following command nmap -v -sS --no-stylesheet -T3 -sU -sV -O -oX <filename.xml> 192.168.69.0/24 Some of the hosts come back with a ...
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1answer
83 views

Inconsistent nmap scan results

I'm working on a program that depends on scanning the local network for all connected devices and getting their MAC address. To do this, I'm running the following command: nmap -sn 10.0.0.* This ...
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3answers
135 views

Why does nmap send two packets in order to test a single port

I run nmap with root privileges using sudo so I assume it has full access to creat raw sockets. Wireshark shows two packets used to test a single port when I used the command sudo nmap ...
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1answer
740 views

nmap unable to split netmask from target expression [closed]

I'm trying to scan my website with nmap to see what is visible from outside...but nmap returns this value... Starting Nmap 6.47 ( http://nmap.org ) at 2015-05-06 01:06 PDT Unable to split netmask ...
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1answer
73 views

How to test iptables settings by port scanning? [closed]

I want to test my iptables and prove that it only allows traffic for given Protocol / Port - combinations. How I can use as a target for a port scan?
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1answer
665 views

Nmap external scan shows port open, ASA says port is not open, but do get an socket

Folks, have a weird one, need your expert help. For one of our heavily used external facing server which came up in an audit, nmap -Pn scan shows the following: Starting Nmap 5.51 ... Host ...
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1answer
127 views

Why is port 443 (but not port 80) being exposed to nmap when iptables is configured to drop the traffic?

A Debian box is running web services on ports 80 and 443 and iptables is configured to allow web traffic only from white listed ip addresses. A second Debian box (that is not white listed) is using ...
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167 views

Unknown device showing up in network scan

I need some help finding a device that has been showing up whenever I scan my network using Spiceworks' "Inventory" scan. I can ping the device, but nslookup returns a non-existent domain, and ...
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54 views

Find any/first alive host in subnet

I'm trying to find a quick way to check if there are ANY alive hosts in an IP range by pinging them. eg: i don't need to know what hosts are alive, just if one or more is responding to a ping. This ...
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65 views

One device shows down when more than 160 ip addresses are scanned with nmap

This is bugging me. I consistently have a single device that fails to respond to an nmap scan when more than ~160 IP addresses are specified. I seem to get mixed results between 150-160 IP addresses ...
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35 views

outlook doing remote portscanning

A while ago I switched my mailbox on another domain and configured outlook with an exchange server on that domain. Recently for some strange reason my hosting provider has been complaining that ...
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470 views

ACL Rule to Open UDP Ports

I have the current rules in an attempt to open port 5060 and 10000-20000 for my VoIP provider. We are on a Cisco 1921 router. This ACL is applied to the WAN port on the router facing the ISP. Nmap ...
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4answers
5k views

Is there a way to see what is actually filtering TCP port communication?

nmap -p 7000-7020 10.1.1.1 Will output all the filtered ports Starting Nmap 6.40 ( http://nmap.org ) at 2015-03-04 12:18 EET Nmap scan report for 10.1.1.1 Host is up (0.00091s latency). PORT ...
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1answer
846 views

Completely getting rid of SSLv3 on Apache

Our security team is asking that we completely disable SSLv3 on some of our servers running Apache. I've used the SSLProtocol entry in the ssl.conf file (like SSLProtocol ALL -SSLv2 -SSLv3) and ...
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2answers
472 views

Generate List of IP's With User Names On Windows Network

We recently setup GFI WebMonitor on our network which is giving me back IP's instead of User's. I'm in the process of determining whether we will be able to implement authentication on the proxy to ...
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2answers
315 views

nmap results to find open ports for SIP

I suspect that a firewall, or other security, on either the router, or on tleilax or doge is causing a problem with SIP calls. How do I establish that the connection is allowed and not being blocked? ...
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1answer
2k views

How to reverse arp using nping for Windows

I would like to send a reverse ARP to resolve an IP address given a MAC address using nping for Windows. The documentation is not clear on how this should work and I'm unable to find any examples ...
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1answer
441 views

Port suddenly closed. How to re-open?

I've written a software module in PHP that manages the saving of data in different data stores (MySQL, ElasticSearch and Redis). To test the module, I've created several test plans in Apache JMeter, ...
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704 views

Fastest way to scan all hosts that are online

I am looking to find all the hosts that are online in a set of networks. I would like to find all hosts that are online in the entire network of 170.10.. (there are ~64K possible hosts). The network ...
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1answer
705 views

Can a port be in the listen state and be closed?

Servers running Debian7.7, Mongodb 1.2.0.6-1.1, Nmap6.0 - Thanks for your time. I've user who can't connect to mongodb from his Win7 desktop. He has mongodb installed on it and he's trying to connect ...
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2answers
295 views

nmap port 3128 shows open but no squid running

Im trying to lock down an Ubuntu server and ran nmap -T4 against my server. Everything looks right except that it shows port 3128 open but I dont run a squid server or anything else I know of on that ...
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197 views

nmap: why is it scanning port 80 with TCP ACK and not SYN?

While reading nmap man pages, I read for the -sn option: The default host discovery done with -sn consists of an ICMP echo request, TCP SYN to port 443, TCP ACK to port 80, and an ICMP timestamp ...
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1answer
35 views

I have a IP address with some open services. How could I contact the owner? [closed]

After having serious problems (DNS incident) I found out an IP address of a machine. Is it in any way possible to contact the owner without knowing anything else like email, domain name or website? I ...
2
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1answer
367 views

HTTP Ports are Filtered on New Virtual IPs in LVS (Linux Virtual Server) Load Balancer

I inherited a Linux Virutal Server (LVS) load balancer on CentOS 5.10. Its been running with no issues for quite some time with no worries. Now when I add a new virutal IP (VIP), all HTTP traffic ...
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242 views

nmap repeats the scan to a specific port multiple time

I scanned a subnet (16 hosts) while dumping the network traffic with wireshark. I did it 2 times and I noticed that in the traffic there is the normal SYN-SYN/ACK and SYN-RST from open/closed port, ...
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2answers
52 views

How best to enumerate a server network

What techniques do you typically use, when you start a gig at a complex environment and no one can tell you what servers are out there, and documentation doesn't exist? I typically start off with ...
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1answer
359 views

ports I open with iptables appear closed [closed]

I opened the following ports with iptables on Debian 7: iptables -X iptables -F iptables -P INPUT DROP iptables -P FORWARD DROP iptables -P OUTPUT ACCEPT iptables -A INPUT -m state --state ...
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1answer
180 views

NMAP service probe or normal port scan [closed]

Apologies - I am very new to these things.I read that nmap-service-probes will display the service that the port is using while nmap -sS will send a stealth SYN which is also capable of ...
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2answers
273 views

How do I test my firewall rules?

I've setup some rules in ufw and I've turned it on. Now I want to ensure my rules actually block traffic. However, when running nmap -PN -p <my_port> <ip> from my local workstation it ...
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1answer
7k views

Two Identical mac addresses on the same lan - Tracking one down?

So I've been playing around with nmap, and found a curious problem, two devices in the same subnet have the same mac address. I would like to track down the second mac, as the first one is the sonic ...
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2answers
1k views

Nmap: find free IPs from the range

Is there a way to scan for free IPs on the network? I use nmap -sP 192.168.1.0/24 but this actually shows hosts that are up.
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2answers
50 views

Can zenmap disrupt my server? [closed]

Title says almost everything already. I'm trying to increase the security on our servers but I need verification that the Information Gathering tool ZenMap or NMap does not disrupt our servers. The ...
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1answer
1k views

nmap and arp-scan inconsistent IP-MAC results

I seem to get variable and inconsistent results for the IP/MAC addresses from a particular machine, using nmap or arp-scan. The machine has 3 interfaces, and this is what it shows: $ uname -a Linux ...
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1answer
353 views

nmap lists host as up despite being black listed

I have an iptables rule setup that marks addresses as suspicious if they connect on certain ports or any unopen ports. If more than three consecutive connections are made without authentication, then ...
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1answer
536 views

Trace /8 address space with nmap

I'm trying to sketch out a network topology map using the following command nmap -sP -PE -PS22,25,80 -PA21,23,80,3389 -PU -PO -oX topology.xml --traceroute 10.0.0.0/8 (10.0.0.0/8 because no one ...
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1answer
2k views

Detect if remote host is running Windows or Samba

From a Linux server, how can I quickly determine if a remote machine is running Windows or Samba? I want to run commands on remote Windows machines (XP and 7) to list the installed software and ...