All Questions
49
questions
0
votes
3
answers
443
views
Understanding how ports work and how are they different from processes?
I've been a part of a network operations team for quite some time now and was extracting a certificate using this command:
openssl s_client -connect <IP>:<PORT> </dev/null | sed -n -e '/...
1
vote
0
answers
264
views
why might nmap on a computer be reporting port 443 as closed on some but not all computers?
When I run nmap event-bridge.twilio.com on roughly half the computers in my network I get this:
PORT STATE SERVICE
443/tcp closed https
When I run it on the other half of the computers in my ...
- 7,232
0
votes
1
answer
123
views
Nobody listens on port, yet something accepts connection on it
Here is some background information first, although it may not be relevant to the problem.
I am learning Kubernetes and I set up a cluster where pi-hole runs as a service. I can access the admin ...
- 11
1
vote
2
answers
3k
views
bitcoin-cli testnet : Could not connect to the server 127.0.0.1:8332
I've installed bitcoin-cli from here
I run the bitcoin core on Ubuntu 20.04 (AWS EC2).
mac-os also experiences similar problems.
Ubuntu 20.04 screen capture for the error messages
The commands I've ...
0
votes
0
answers
847
views
What ports range is safe from taking by Windows 10
I wrote small program and I would like to use some TCP ports. Same ports for a longer period of time. The problem is each time Windows 10 wakes up it makes its mind which ports to reserve for its ...
- 740
0
votes
0
answers
480
views
How can I do a bi-directional Port-Forwarding (flow encapsulation)?
I have two applications: a client and a server which communicate through port 1234. For some reasons this port is blocked on our system but everything works correctly on port 1235 (checked with two ...
- 1
2
votes
0
answers
2k
views
WebSocket connections originating from local network all use same client-side port (instead of ephemeral) when connecting to local webserver - Why?
I set up a webserver on a virtual machine on my home desktop. I have my router forward several ports (80, 443, etc) to my desktop, when then forwards them via NAT to the virtual machine (see diagram ...
- 21
0
votes
0
answers
783
views
After opening port 443 in windows firewall as inbound rule, I cannot see it when I run 'netstat -an'
As an inbound rule on Windows 10 firewall, I added port 443 as TCP connection allowing all types of connections. However, I cannot see it when I run 'netstat -an'. How can I get it so that I see my ...
0
votes
0
answers
998
views
java.exe opens up hundreds of ports on 127.0.0.1 on a windows 10 computer and listens to itself
After I ran netstat -ab with admin right on my win10 computer, which is not running anything "java" related on the desktop nor there is "java.exe" in taskmanager's "detailed ...
- 103
1
vote
2
answers
2k
views
Packet reaches OS but not the process
Sorry if my issue is a bit hard to summarize in the title. That is the best I could come up with.
TL;DR Version: How do I debug when packets reach OS, but not the destination process?
Explanation: I ...
- 123
4
votes
1
answer
5k
views
How can I know what is preventing my socket to bind to localhost:50060-50959
I am using this Python code to listen to a port on my Windows 10 system:
import socket
for port in (50059, 50060, 50959, 50960):
try:
print(socket.socket(socket.AF_INET, socket.SOCK_STREAM)....
- 1,728
0
votes
2
answers
592
views
how to run mincraft server on linux
I wish to run minecraft server om my linux mint 19.0, but I have some troubles, I can start it in local, and connect by 127.0.0.1:25565 but i can't run it on my ip in inthernet, 4 example my ip is 2....
- 101
0
votes
2
answers
3k
views
ipv4 and TCP/UDP ports: Multiple instances of the same program, same port number
I am trying to learn about ipv4, TCP and UDP protocols. I have read that the purpose of a port number being assigned in a TCP or UDP datagram is to ensure that the sending/receiving machines forward ...
- 2,984
5
votes
1
answer
10k
views
How does TCP handle multiple requests targeted to one port?
As a server may get many requests from clients at the same time to a particular port, for example port 80 for HTTP objects, how does the server handle simultaneous requests?
- 153
1
vote
1
answer
3k
views
Using lsof and fuser I can't find the process listening on a strange port
I've read other posts about finding the process ID and what's listening, but sadly couldn't get my issue solved. So, apologize if I missed some info about it.
Running netstat I found a port that I ...
- 13
0
votes
1
answer
79
views
What are network ports internally? [closed]
I know there will be multiple ports in the host/computing machine for each of the services that i hosts on the network.
But i want to understand what are these ports internally?
Below is my ...
- 659
7
votes
1
answer
60k
views
Access local webserver on port 8080 in home network using IP-Address
this is quite new to me so I hope it is clear what I try to ask.
On my windows 10 pro I have installed a small application which runs as a webserver on port 8080. I can access it using localhost:8080 ...
- 173
38
votes
3
answers
71k
views
How are source ports determined and how can I force it to use a specific port
When I connect to https://www.google.co.uk this changes to 216.58.198.228:443. Then a connection to me opens on [My IP Address]:63998.
My question is how is 63998 port choosen and is there a way of ...
- 416
0
votes
1
answer
3k
views
Cannot open a connection from a PC but the host can be reached from other computers
When I use telnet to try a port on a server, I get the following:
telnet x.x.x.x xxxx
Connecting To x.x.x.x...Could not open connection to the host, on port xxxx: Connect failed
...
- 101
1
vote
2
answers
7k
views
What are the default nmap options?
Which options are used by default, when the user fires
# nmap target
without any explicit option?
I am going to write the defaults of the three options I consider the most important. It would be ...
- 171
3
votes
2
answers
2k
views
IPTables - Redirect traffic based on country
Is there any way how to allow TCP traffic only from specified countries on a specified port and the rest of traffic redirect to another IP/port using iptables ?
- 125
0
votes
1
answer
766
views
Can two different applications bind the same port on a host if they use different protocols?
my question is quite clear I think. If two applications use different transport layer protocols (e.g. TCP and UDP or something else) can they open the same port number?
How does the OS do the ...
- 1,863
1
vote
1
answer
86
views
Where do I start to troubleshoot this strange activity from my firewall?
I noticed that my firewall yesterday blocked outgoing attempts starting at port 61494 and worked its way up to 62381, making a TCP outgoing attempt at each port once. The remote IP address seems ...
- 131
0
votes
0
answers
1k
views
Tcp connection target machine actively refused
I have a simple TCP client/server program on two laptops. The server should work fine as I use "netstat -anb" and the server shows up as listening, "0.0.0.0:102", then my client connection failed, ...
15
votes
5
answers
16k
views
What ports are used by an application [duplicate]
I'm testing an application which opens its own ports (acts as a server for these ports, hence listens at that ports) and where the same application connects to ports bound by other applications (acts ...
- 489
0
votes
1
answer
2k
views
List all open sockets in /dev/tcp/localhost/
Is it possible to list all open sockets in /dev/tcp/localhost/ on a Linux machine?
I want to list all sockets where the following command would return 0:
timeout 2 bash -c "cat < /dev/null > /...
- 127
0
votes
1
answer
982
views
TCP server listen and client listen windows software
I am using Windows OS on an amazon cloud AWS with static public IP.
On this machine I need to set up a TCP server to listen on port 2204 for raw data that will arrive from a GPS base station over TCP ...
0
votes
0
answers
85
views
Hiding port number from address.
I have centos 6.5 running some web apps. Currently due the following port forwarding rules, I am only able to access my public content using 127.0.0.1:8080/
Is there anyone to just use 127.0.0.1 ...
- 87
4
votes
3
answers
9k
views
How to force a process transmit over UDP instead of TCP?
I 'm running an ffserver process on a Linux machine, in order to achieve video streaming via ffmpeg. However, there is a delay on video streaming. On ffserver configuration file I define Port 8090.
...
- 439
2
votes
3
answers
7k
views
Is the same port acting as both client and server?
i find something strange in this netstat output. the output is taken using netstat -a -n -o -p TCP command on win 7.
Proto Local Address Foreign Address State PID
TCP ...
- 123