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votes
2answers
78 views

How make a port appear open with an nmap scan

To avoid someone knowing which port are open on my machine, I thought it would useful to open all unused port so that the nmaper is unable to identify which port are really open. How make a port ...
0
votes
1answer
60 views

Scan network with Linux kernel command

Does Linux kernel provide some utility familiar to nmap for simple network scanning to discover attached nodes?
1
vote
3answers
502 views

NMAP network scan shows IP-addresses and MAC addresses of items that are then missing from a subsequent arp-cache dump?

The logic I have is this get the definition of the subnet use nmap to scan every item in the subnet to populate the arp cache use the /usr/sbin/arp tool to dump the arp cache parse the arp-cache to ...
1
vote
2answers
583 views

ARP hostnames problem

I am having problem with viewing hostnames of devices located in my LAN. On my first laptop (Ubuntu 18.04 LTS Desktop edition) result of following command: arp -a Is exactly what I want: X (192.168....
0
votes
2answers
2k views

nmap “filtered” results on a pretty naked server - could “filtered” just mean “silence”?

I get unintuitive results from "nmap -A " which I want to clarify. Setup: sshd (ssh deamon service) is successfully running. postfix is installed and so smpt service is running. However, it only ...
1
vote
1answer
409 views

How to scan outbound closed ports with nmap?

I just noticed that my server is being blocked for rsync from a firewall outside of my server, so I can't rsync to any target. Now, I would also like to know what are all the ports that are being ...
3
votes
3answers
11k views

How to protect against port scanners?

Is it possible to prevent nmap from observing my machine entirely? After dropping all incoming connections with iptables port scans return as "filtered". It'd prefer if nmap couldn't see what ports ...
6
votes
2answers
8k views

Nmap scan for SNMP enabled devices

Nmap scanning network for SNMP enabled devices: sudo nmap -sU -p 161 --script default,snmp-sysdescr 26.14.32.120/24 I'm trying figure out how make that nmap return only devices that have specific ...
2
votes
1answer
4k views

nmap raw packet privileges not working (“operation not permitted”, even as root)

Why am I getting the "operation not permitted" with nmap - even when executed as root? $ sudo nmap 192.168.1.2 Starting Nmap 7.12 ( https://nmap.org ) at 2017-01-13 02:12 CST sendto in ...
-1
votes
1answer
101 views

nmap command - suspicious behavior [closed]

I'm learning Linux on Cisco, and they display a certain message about the nmap command : CAUTION: To avoid suspicion of using the tool to find a way to attack the systems on your network, it is ...
1
vote
1answer
143 views

How to make a port appear as being open every time it is scanned with nmap independently of its open/close state?

To make one open port undetectable with an external nmap scan, it seems easier to make all other scanned ports appear as being opened than to try to make this port appear as being closed. How can I ...
1
vote
1answer
2k views

telnet to an host/port works while no service on this host listening on this port

I am crashing my head against the wall with this one... I run nmap from my desktop for a specific server I have, to check some opened ports which could be security issues. It returns ports which ...
3
votes
1answer
104 views

Nmap Changed My Network?

I am running a clean install of Fedora 24, and I am not sure if I accidentally did some weird key combo, but I entered: nmap -sT -Pn [IPaddress] and, for some reason, this added a PCI network to my ...
1
vote
1answer
3k views

How to proxy nmap and dns resolution of nmap

How to use nmap and dns resolution of nmap over proxy? I tried proxychains, but for dns resolution it doesn't work, it's known bug as I read on some forums. It works well without dns_proxy feature in ...
2
votes
0answers
351 views

why does nmap shows same ports sometimes as filtered and sometimes as closed?

When I'm scanning port range 4050-4060 of an smart metering device all ports are reported as closed: root@abc:~/rvm/dlms# nmap -p 4050-4060 192.168.1.242 Starting Nmap 6.47 ( http://nmap.org ) at ...
5
votes
1answer
4k views

How does FING (or any of the IP/MAC Address Mappers) work?

Per this comment, I'm going to take advice and ask this as a separate question. I am trying to learn more about networking and security and want to play with tools to help increase my understanding. ...
0
votes
1answer
75 views

Value of nmap option

I've found in some docs of port knocking, that it is used the option --host-timeout I don't understand why is 201 assigned to it? e.g.: nmap -Pn --host-timeout 201 --max-retries 0 -p 7000 192.168.80....
9
votes
3answers
2k views

How many bytes occupy a simple nmap to a host?

Today the IT manager got angry because I used nmap on the 3 servers I manage to see what ports they had open. I know I could have used netstat inside the host' shell. He told me that "If the network ...
4
votes
3answers
10k views

What's the most effective way to detect nmap scans?

I am interested in detecting any nmap scans directed on a (my) GNU/Linux host. I would like to use snort in combination with barnyard2 and snorby for this, or if possible to perform a signature-based ...
2
votes
1answer
1k views

nmap won't recognize a hostname on my local area network

Scanning the machine on the LAN with my laptop, I got this: gabriele @ osiris { ~ } [ Tue Oct 07 ] [ 08:49 PM] nmap -sP 192.168.1.236 Starting Nmap 6.40 ( http://nmap.org ) at 2014-10-07 20:50 CEST ...
1
vote
1answer
509 views

masscan. how to configure Linux?

I've set this in my sysctl.conf: net.netfilter.nf_conntrack_max=268435456 Because, this border 16,777,216 achieved very quick. Also, I've decrease timeouts: net.ipv4.tcp_fin_timeout = 30 net....
1
vote
1answer
801 views

Nmap too slow with a network that can't access to internet

I am using CentOS 6.5 and Nmap 5.51 I want to find all alive IPs in a LAN between two IPs Easily get the answer sudo nmap -sP 192.168.1.100-200 my problem when my network can access to internet ...
2
votes
1answer
621 views

Running a local port scan and found open ports but, don't know what they're used for?

I wrote a very basic python script to port scan my system. I'm running linux-mint lisa: open_ports = [] for port in xrange(65536): conn = socket.socket(socket.AF_INET, socket.SOCK_STREAM) ...
3
votes
3answers
1k views

Questions about nmap

I have several questions about nmap. First, nmap can detect servers via: link-layer network-layer transport-layer What are the differences (not in the layer, but in the way that nmap does it) and ...
4
votes
1answer
457 views

Doing nmap on a network

I used nmap to scan all the ports in the hosts in a network by using the command: $ nmap 172.31.100.0/24 What I found is that it showed the following in the result: Nmap scan report for 172.31....