In computer networking a port is a software construct serving as a communications endpoint in a computer's host OS.

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Only HTTP(S) port is open. Why do I need to worry about unpatched software?

Unpatched software poses no risk by themselves. They're only problematic when someone exploits it. How could malware get into my system if I do have unpatched software in general and I'm connected to ...
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2answers
60 views

Which all ports are in danger and needs to be closed with immediate attention?

This is the nmap scan results on my server (used for email and web serving) from a remote scan. Which all ports are in danger and why? PORT STATE SERVICE 21/tcp open ftp 25/tcp open ...
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2answers
303 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?
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2answers
65 views

What is the safest way to ssh to a machine behind a router?

I am thinking about forwarding port 22, to 22 on the machine behind router, but is it safe? Anyone can try to connect to my public IP on port 22 and then indefinitely try to guess user and password. ...
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3answers
55 views

What Mechanisms Keep Network Processes (and Applications) Sandboxed

This question stems from my other question, sorry if it is too similar. Now I would like to know what mechanism is used to sandbox network processes and (if relevant) individual programs, if at all? ...
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1answer
165 views

What does Msgsrvr and Scientia-ssdb do?

I'm having a task in a computer security class in school where I'm supposed to scan a host for open ports in order to find out what services is being run there. I have found out (among other things) ...
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1answer
88 views

Telnet Open, is this an exploit? [closed]

I am pentesting a server, and it appears my ports are open for telnet. Upon accessing telnet, if I type "help" I only get these commands: telnet> help Commands may be abbreviated. Commands are: ...
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1answer
61 views

Are these port secured on my AP?

I'm doing a project for my high-school and I'm trying to get the best security for my network. I've made almost everything in my access-point configuration and I have only 3 tcp/ports open on my AP: ...
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2answers
113 views

Protecting against GCHQ port scans: How does TCP stealth work?

Today I read the first time about a draft of TCP Stealth which should serve as a protection against GCHQ and NSA vulnerability scanning(Source: https://en.wikipedia.org/wiki/TCP_Stealth): The ...
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2answers
398 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 ...
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2answers
71 views

Impossible to make connections through closed ports?

If you have closed all your ports on your internet protocol, you cannot make a connection to that internet protocol. So how do attackers (DoS or any other means that need a connection) make a ...
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1answer
83 views

Internal IP addresses allowed access to all DMZ hosts

Hi basically I'm doing a vulnerability assessment for at the moment. The setup includes a DMZ with a single firewall and an internal network (3 legged network model employing a single DMZ) but on the ...
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2answers
128 views

Does Nmap requires a closed TCP port to do OS fingerprinting?

I was checking the security of a server by running Nmap. Last time it gives me the following results, indicating that OS could not be fingerprinted: PORT STATE SERVICE VERSION 21/tcp ...
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2answers
138 views

How common is port-knocking? [closed]

Today I read about port-knocking for the first time. It has been a pretty known concept for more than ten years, but I don't know anybody who uses it for their servers. How common is the usage of ...
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1answer
85 views

Detecting port scans in OSX kernel

Is it possible to detect port scans on OSX at the kernel level? I would like to write a kext that detects the ip addresses of systems scanning my computers ports. How exactly does a stealth scan ...
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0answers
93 views

OSSEC, what is it telling me about port changes?

I've been diving into OSSEC for the last couple of months, but I feel unclear on one of it's alerts. I've provided the alert below. The main difference I see in previous output and current output is ...
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1answer
73 views

How to check whether firewall allows traffic on specific port but not listening on the port [closed]

I have client / server and there is a firewall between them.The server is listening on a port and I want to check if this port is allowed by the firewall. I can only know the ports that the machine ...
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1answer
60 views

Web browser initiating connection on non-standard ports. Should it be blocked?

I am doing some egress monitoring on my computer. Once in every few days, I would find some strange connections being logged, which I believe is initiated by the web browser through a related but not ...
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2answers
837 views

I ran a netstat on my server and port 80 is listening, does that mean it is open and vulnerable to attacks? [closed]

Sorry I am just getting into Web Development and trying to learn more about servers and PHP, so I downloaded the LAMP stack on an Ubuntu14 OS and started an apache2 server. tcp6 0 0 :::80 ...
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1answer
120 views

Is there a way of determining if tor is running on a remote machine?

In most of the companies, IT guys block some sites and by using TOR or other VPNs people walk around these blocks and gain access to blocked content. My question is, assuming TOR is running on ...
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2answers
48 views

Only allow access to specific service running on computer in Demilitarized Zone over internet

If a computer (running different services such as ftp and ssh) is placed on a Demilitarized Zone, will all of its services automatically be accessed by anyone on the internet? If the answer is yes, ...
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1answer
66 views

How to turn of telnet and FTP on Thomson 789vn router? [closed]

I have run a port scan against a Thomson 789vn router and have noticed to my surprise that its HTTP as well as telnet and FTP ports are open. How can one turn off telnet (also FTP) using the router's ...
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1answer
88 views

NMAP not reporting open ports with -sS scan

Is there any reason why an -sS scan (or most others) would not report an open port that doesn't have a service attached to it? For example, in a regular -sS scan, the following port will be missing, ...
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1answer
78 views

Is it possible to find out what a remote user is trying to do connecting to a closed port?

From my iptables log, I can observe a particular remote IP address trying to connect to my server from port 80 to a private port number: Jul 09 01:24:41 example.com kernel: IPTABLES: IN=eth1 ...
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2answers
136 views

Nmap stealth scan shows that port is filtered

The title is really bad, but I was able to find better. I have installed Debian on VMware, and set iptables to block any traffic except port 80 (inbound and outbound). When I run a nmap scan it shows ...
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2answers
2k views

VPN blocked ports problem

I use VPN quite often in public places where I don't want anyone to read my web traffic. However, some public places have firewalls that block ports required to establish a VPN connection (I usually ...
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2answers
150 views

Creating port-specific SSH authentication for the same user

I have a Linux server running SSHD and would like to know if its possible to configure it, such that from within the LAN you only need a RSA key to authenticate (on port X), but from outside the LAN ...
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2answers
1k views

Is my ISP doing a port scan on my computer?

I have been logging incoming connections with iptables for a while and I have been observing the following popping up periodically: 11:45:10 my.com kernel: IPTABLES: SRC=220.255.XX.XXY ...
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2answers
204 views

What security does an ISP provide for its customers?

I've heard that ISPs provide some kind of protection; using NAT and firewalls, to prevent hackers from using tools such as nmap to attack customers from over the Internet. What other technologies are ...
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1answer
340 views

MAC-address restricted port forwarding

I have an ASUS RT-AC68U router and would like to set up port forwarding, but I would like to restrict which MAC addresses can connect through that port. My use case is that I'll have a live camera, ...
0
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1answer
143 views

Finding the firewall port that filters internet traffic [closed]

In my office, we have static IP's for each system. All the internet traffic from our systems are filtered with a Fortiguard firewall. Is it the default gateway where the firewall is installed? How can ...
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1answer
207 views

Outbound Port 443 Open but Not Allowing SSH [closed]

My college wireless network has a firewall blocking all outbound ports except 443 and 80. The wired network, however, has none of these restrictions. I can connect to HTTPS sites (obviously). On my ...
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3answers
98 views

Is forwarding a port(s) a security risk to all computers on the network or just one?

I know forwarding ports can add some security risk, but if I forward a port to a computer, say running linux, would it add a security risk to all computers on my network or just the one?
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1answer
2k views

Setup of Kali Linux for reverse shell connections over the internet

I am running Kali Linux as a VM on my Windows machine which is NAT'd behind my company network, if I wish to pen test a website for a client and believe that a reverse shell is possible, what is a ...
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3answers
2k views

Exploiting through a filtered port

I'm doing some pentesting against a machine the lecturer set up in the lab. NMAP shows port 445 to be filtered and Nessus confirms the ms08_067 vulnerability is present on that machine. I tried ...
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1answer
254 views

Can closing port 80 lead to more security?

If a website is running on HTTPS only, is it reasonable to close port 80 of the web server and only leave port 443 open? Does this action provide more security for the website?
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1answer
532 views

Does connection that use 0.0.0.0 in Foreign Address secured?

When I run my application on Centos the specific process opens port that listens for connections from localhost, but uses 0.0.0.0 in Foreign Address. Is it secured? netstat -plunt Active Internet ...
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3answers
193 views

What are ports? [closed]

I just wanted to know what are ports. Can someone explain to me what a port is?
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3answers
1k views

Why P2P need portforwarding when behind NAT? [closed]

Correct me if I'm wrong, but for a node to participate in peer-to-peer, if it's behind a NAT, it most port forward to be able to connect. Why is the port forwarding necessary? I know there's ...
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1answer
478 views

Netgear WNDR4000 open port 53

Why is port 53 open on the WAN side of the router? And more importantly how do I close it? Port 53 is not one of my forwarded ports. Discovered by doing nmap -pT:1-64 <my-external-IP> -Pn ...
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3answers
3k views

Why is system32/ntoskrnl.exe blocking port 80? [closed]

Today I've tried to start the Visual Studio Developer IIS as usual on Port 80, but this time it has quit with an error that port 80 is already in use. With netstat I've found out, that an application ...
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2answers
1k views

Port list according to vulnerability [closed]

I'm looking for a list of ports sorted according to the number of vulnerability you can find for that specific port (considering of course, the service installed in the default port). Example: ...
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3answers
677 views

Why block network ports?

There was another good question here on why you should block outgoing traffic: Why block outgoing network traffic with a firewall? But I was hoping to get an answer on why it is a good idea to block ...
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5answers
2k 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 ...
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1answer
183 views

Is it possible to scan a remote host in another network if I know a port that is opened?

First of all, this question is not the same as is it possible to test out remote host by using nmap?, because on that question, the questioner is asking for something impossible due to NAT's nature. ...
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1answer
964 views

What are the ports used by Online Email Accounts such as Yahoo Mail, Gmail, etc.?

Let us say that I send an email using Yahoo Mail or GMail. Can this email be intercepted using a packet sniffer? On which port does the email travel? HTTP, SMTP, POP3?
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Is Port Forwarding for bit torrent risky?

I have found that my connection decreased suddenly when downloading torrents. I diagnosed it with bit torrent and the answer is that i should do port forwarding on my modem/router! Is it risky?
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115 views

Hardening Services, Ports on OSX

People boast about OSX Security, yet I find it very hard to find a comprehensive manual in regards to any equivalent Services and the ports they use. I am aware of lanchd and launchctl and Lingon is ...
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1answer
115 views

Understanding a Zenmap output

I'm running Zenmap on my Windows 7 laptop. I ran an intense scan with UDP targeting my router 192.168.1.1.I realize that I'm probing into the back end of the router from the inside and that any open ...
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4answers
7k views

Router Ports open

What ports on my home router should be open, say if I'm only using it for browsing the internet. Right now these four are open, 23/tcp open telnet 53/tcp open domain 80/tcp open http ...