Questions tagged [nmap]

a free and open-source port scanner, operating system fingerprinter, and service fingerprinter

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37
votes
5answers
107k views

How to close ports in Linux?

I have some question in closing port, I think I got some strange things. When I use execute nmap --top-ports 10 192.168.1.1 it shows that 23/TCP port is open. But when I execute nmap --top-ports ...
22
votes
3answers
68k views

How to “close” open ports?

A few days ago I started to care a lot about my data security, I end up nmaping myself with: nmap 127.0.0.1 Surprise, surprise, I have lots of active services listen to localhost: $ nmap 127.0.0.1 ...
37
votes
2answers
105k views

Why are some ports reported by nmap filtered and not the others?

I'm scanning a server which should have a pretty simple firewall using iptables: by default everything is DROPped besides RELATED and ESTABLISHED packets. The only type of NEW packets allowed are TCP ...
13
votes
1answer
6k views

What's the gnu-netcat's '-z' equivalent option in nmap-ncat?

I check for a listening port on a service prior to running a script using this : until nc -z $HOST $PORT do echo "waiting for service to be available..." sleep 0.5 done exec "/my/script" It ...
6
votes
3answers
1k views

Difference between `nmap local-IP-address` and `nmap localhost`

The following IP address is for my network interface $ nmap 192.168.0.142 Starting Nmap 7.60 ( https://nmap.org ) at 2019-03-09 11:33 EST Nmap scan report for ocean (192.168.0.142) Host is up (0....
2
votes
3answers
80 views

How to scan my computer's UDP ports

What command can I use to port scan UDP? I hear that UDP scanning has some specific issues, that do not apply to TCP scanning. I tried running sudo nmap -p0-65535 -sU 192.168.1.97. But it has been ...
18
votes
3answers
47k views

Can nmap display only hosts with specific ports open?

Can nmap list all hosts on the local network that have both SSH and HTTP open? To do so, I can run something like: nmap 192.168.1.1-254 -p22,80 --open However, this lists hosts that have ANY of the ...
4
votes
3answers
674 views

Understanding suspicious SSH commands

I have a dedicated hosting server that has few websites running. I recently accessed my server thru terminal cmd line and noticed that the last few commands that were executed look suspicious and I'm ...
2
votes
1answer
1k views

Can you send a TCP packet with RST flag set using IPTABLES as a way to trick NMAP into thinking a port is closed?

I am learning Nmap and a thought occurred to me with regards to a SYN scan... A SYN scan sends an empty TCP packet with the SYN flag set to illicit a response from the target of either RST, ...
0
votes
1answer
527 views

PostgreSql port open on NAS Synology DiskStation (DS216j)

How is possible to check if the port 5432 of my NAS synology DiskStation (DS216j) (IP address 192.168.0.16 ) is open? I have (in the control panel of the NAS), enabled the firewall and created a rule ...
0
votes
2answers
7k views

How to generate random IP addresses

$ nmap -n -iR 0 -sL > RANDOM-IPS-TMP.txt $ grep -o "[0-9]*\.[0-9]*\.[0-9]*\.[0-9]*" RANDOM-IPS-TMP.txt | egrep -v "10.*|172.[16-32].*|192.168.*|[224-255].*" > RANDOM-IPS.txt egrep: Invalid ...