All Questions
22
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
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
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
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
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
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
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
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
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
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