Questions tagged [port]

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iptables: Failure when trying to block port access for most IP addresses, except for a few

I am using Debian 8 linux. I'm trying to block input access to a few ports for most IP addresses, except for a small, select list of IP addresses. I am doing the following, but it does not seem to ...
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How to find port allocation? Bind for 0.0.0.0:80 failed: port is already allocated

My docker-compose.yml version: "3" services: redis: image: redis restart: always postgres: image: postgres environment: POSTGRES_USER: user POSTGRES_PASSWORD: ...
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Unable to get PID on a Listening port for Solaris

I'm using solaris SunOS myhost4 5.11 11.4.42.117.3 sun4v sparc sun4v non-global-zone I'm sure that port 7777 is in use as the telnet is successful as below: $ telnet myhost4 7777 Trying 10.23.52.219.....
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How to debug source IP which try to access SSH server through port forwarding by SSH

my case is likely following case: SSH client(192.168.0.11) -> public cloud VM with SSH server and setup port forwarding (139.90.90.90)(CentOS7.9)-> one internal SSH server(10.24.24.24)(CentOS 7....
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Can a NAT router run out of ports?

The highest TCP port number is 65535. If a router doing NAT uses an ephemeral port for each connection made to the internet on behalf of the hosts on the internal network, does this mean that it is ...
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Raspberry Pi 4 doesn't show USB camera as ttyUSB

I have an RPi camera and a USB camera connected to my RPi4. lsusb: pi@raspberrypi:~ $ lsusb Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub Bus 001 Device 004: ID 0c45:636b Microdia ...
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lspci command doesn't detect monitor through mini dvi port

I just wired a just received 2005 Toshiba TDP S25 Projector VGA to the mini dvi port of my GP66 Leopard via an adapter. However, when I select "Computer 1" on the toshiba menu I have a mere &...
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Port is shown as "open", then as "filtered" on CentOS Stream 8

I have made a fresh install of CentOS Stream 8 on a machine. This machine needs to connect to a Foreman Smart Proxy on port 443. If I run nmap immediately after machine boots up, it sees the port as ...
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Nmap Shows Different States of the Same Port with Different Scan Methods

When I launch an -sA scan of a certain IP address, it shows port "80" as "unfiltered". Code is below. sudo nmap -sA -vv -p 80 192.168.0.30 -Pn Host discovery disabled (-Pn). All ...
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Telnet error - "Connection timed out"

I am trying to telnet a port at a client's location. telnet someexampledomain.com 25 It shows: Trying someexampledomain.com... telnet: connect to address someexampledomain.com: Connection timed out ...
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How to limit web usage with nftables?

Between certain times, I would like to limit the amount of internet browsing I can do to force myself to focus (something like visiting ~3 sites per minute). This is what I came up with: table inet ...
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Local port forwarding on Ubuntu 20.04?

I have a service listening on port :3000. However, I would like to change that to port :8080. Unfortunately, the program that I'm running does not allow me to change the listen port. Is there any way ...
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Can two servers bind the same port?

I was surprised to discover that two servers I'm maintaining are both able to listen on port 3000 in development at the same time. With the first server running, netstat shows ▶ sudo netstat -nap ...
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clearing port in use manually vs waiting 60 seconds

running lmgrd which is a license manager executable that comes with paid-for software, in a work environment. I often resort to kill -9 <pid> of existing lmgrd processes found by doing ps -ef | ...
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bash script, check port response with bash's built-in /dev/tcp, time delay | hangs | speed up

With this scripts i check if a host is response on a given port with the bash's built-in /dev/tcp. I can use ip address or domains(hostnames). Script 1 #!/bin/bash HOST_NAME="127.1" ...
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How to drop packets to port 5901 other than localhost with nftables

I was trying to block VNC port 5901 from internet but accessible from localhost. I have a docker container running on the server, which works fine. After the following 2 commands, I still can access ...
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Docker expose port only to VPN

I'm setting up a DNS filter using Pi-Hole and OpenVPN on a VPS. Pi-hole is running in a Docker container and exposes port 80 for its web interface. How do I expose this port only to traffic ...
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firewalld - where are the numeric firewall port numbers mapped to the service name?

# firewall-cmd --permanent --add-service=nfs # filewall-cmd --permanent --add-service=rpc-bind in RHEL/CentOS 7.9 if I do the above, what numeric port numbers are opened in the firewall? Where is the ...
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Proxmox host - prevent port scanning outbound

I need some help to protect our /24 subnet to be abused by our customers which receives KVM instances with dedicated IPv4. We would like to detect outbound port scanning activities and brute forcing ...
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ufw won't allow connections to postgres port 5432

With ufw disable on remote postgres system i'm able to connect from my local system However, the connection does not work when I ufw enable as shown below: C:\Users\HOME>telnet 80.240.24.195 5432 ...
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Problem with server - client connection

I run PyCharm on a Debian 11.1 machine and I want to use the Remote debugging with the Python remote debug server configuration. In this debugging procedure PyCharm emulates a server which connects to ...
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-1 votes
1 answer
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INVALID_PORT Error from firewall-cmd

When I try to add a port via firewall-cmd --permanent --add-port=XXXXX/tcp I get the error Error: INVALID_PORT: XXXXX Why?
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How to receive a file and save it with socat

**** This is for learning purpose. I just like to deep dive into sockets, tcp, packets, etc. For doing tests and learning, I began to "play" with socat CONTEXT (tests) : 1- Bind a port to a ...
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USB - usb2com device connect and disconect in Debian 11 (bullseye)

I am using Debian 11 (bullseye) a new installation at DELL T5610 workstation. When connect an USB to COM port device it is recognized and mounted properly for a while and then it gone Initial mount is ...
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iptables/firewall-cmd DROP rules set last block ip rule set before

As follow is the list of the iptables rules that I have : # firewall-cmd --direct --get-all-rules ipv4 filter INPUT 0 -p tcp -m state --state NEW -m tcp --dport 22 -j ACCEPT ... ... ipv4 filter INPUT ...
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Stop Application from listening to a particular port

Background We would like to configure a Linux machine so that it doesn't automatically listen to a port; whether a default port or not. We are using Oracle Linux and RHEL. Issue How can we prevent our ...
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4 votes
1 answer
247 views

scp when both hosts are remote and use different ports

I am reposting a slightly edited version of this Ask Ubuntu question SCP with two different ports, as the answer there that works with command-line options only (without modifying ssh_config) no ...
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Connection refused between 2 linux containers

On my host Ubuntu 18.04 I am running two lxc containers using default setups. Containers use Ubuntu 18.04 as well. I have an app running on container1 that offers an https based service on https://...
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What is ftranhc service?

This the output of a nmap $ sudo nmap 192.168.0.33 Starting Nmap 7.80 ( https://nmap.org ) at 2021-11-16 16:13 UTC Nmap scan report for 192.168.0.33 Host is up (0.0062s latency). Not shown: 997 closed ...
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iptables Forwarding and port blocking

I have created the following Network in Virtual Box: Linux Internal PC with 1 Static IP: 10.10.10.2 Linux Gateway/Firewall with 2 Static IP's and 1 NAT: 10.10.10.3 | 11.11.11.2 | NAT Network Card ...
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Unable to connect telnet to mysql listen ip port from remote host

I m able to telnet locally to mysql process like below: I have also made sure MySQL process is listening on all IPs by setting bind-address = 0.0.0.0 as evident below: root@localhost:~# netstat -plutn ...
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Has my OS been hacked?

My phone has a malware that creates a virtual disk on the partition, so upon factory reset, it can continue is work. (I believe its a Chinese cryptojacking bug.. Runs a whole bunch of encrypted ...
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3 votes
1 answer
198 views

netcat closing connection on localhost listening end after connection attempt

Ι am nc-listening on localhost:2500 ▶ nc -l 2500 _ On another terminal I am trying to connect to this listening end ▶ nc -zv localhost 2500 nc: connectx to localhost port 2500 (tcp) failed: ...
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What's the idiomatic way to allow incoming connections on a TCP port, as of 2021?

It's been years since I last fiddled with firewall rules; and I remember the iptables chains for input, forward and output, and their various rules. But the times, they have a-changed, and today ...
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Does there exist an epheral port allocation service?

Following up on this question, it would seem that a server that allocates ports within a namespace would be an obvious and useful capability. One use case for such a service/server would be a ...
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I have added port to firewalld but ECONNREFUSED will return every time I send a request

I'm working on Centos7 VPS and I have added port 9200 to firewalld, but I can not request this port and I will get this error Error: connect ECONNREFUSED from Postman. My firewall status: > ...
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How to find USB device port in Linux?

I have a USB device connected to my computer, it is this one: I want to use it in Python according to the example in this link. How do I know what to put for port (instead of 'COM1') in the line with ...
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Get free/used ports in a specific range

Is it possible to get either the free or used ports between a specific range? If yes, whats is the command? Thank you in advance!
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list out all computer node connected to master node

I have HPC access, connected to other HPC via local IP or just simple hostname (i.e., compute1 or node3). I can log in to them by typing "ssh node3" or its IP like "ssh 10.2.6.20" ...
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1 vote
1 answer
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Website served on port 80 unreachable from my phone in the local subnet

I'm building a website on my laptop. To see how it renders, I serve it locally on port 80 with lighttpd. I can then open it in my laptop's browser via any IP or URL referring to the laptop http://...
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How to do Monitoring in a restricted network without Proxy

We want to monitor Customized Ubuntu 20.04 Kiosk Machines that run continuously in a very restricted Bank Network. For this, we tried to use CheckMK but that does not seem to work because of the ...
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On ubuntu 20.4, after starting Cassandra with systemctl, no process listens at port 7000/9042/7199

I installed a 3-nodes Cassandra cluster on three machines (all running Ubuntu 20.4) . I could start either via systemctl start cassandra, or via cassandra -f command. But I noticed that if I start via ...
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13 votes
9 answers
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What's the point of firewalling outgoing connections?

I have a firewall (csf) that lets you to separately allow incoming and outgoing TCP ports. My question is, why would anyone want to have any outgoing ports closed? I understand that by default you ...
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rhel + any best practice to minimize the CLOSE_WAIT sessions from linux side

when we perform the following cli on our rhel machine we get more then 600 CLOSE_WAIT lines lsof -i tcp:8088 | grep CLOSE_WAIT java 31100 yarn 385u IPv4 208022048 0t0 TCP master02.hgti.com:...
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how to know what the process that connected to my machine VIA specific port

with the following command I want to get which are the IP's that connected on my machine with port 8088 18.23.292.9 is machine that resource manager service is running on with port 8088 ss -tanp | ...
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Setting which ports to use for passive FTP connection with Linux's ftp client

I'm trying to connect to a FTP server behind a firewall that allows incoming connections in the range 6100-6200 only. I have successfully connected to this server using curl like this: curl --ftp-port ...
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Is changing a service's port from one to another done by shells?

Some companies change the port address (number) of a service from one to another; for example, some companies change the address of SSH port from 22 to something else. Is changing a service's port ...
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2 votes
1 answer
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Non root user is not able to open any ports

I have an embedded Linux System built using Yocto. Just out of build, it only had a root user. I created a new user. This new user is not able to open any ports on the system even though they are ...
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SSH RemoteForward port to remote Ubuntu is not working

My local machine is mac, I am connecting to a remote Ubuntu 20.04.2 LTS machine called mini. Bellowing is the ~/.ssh/config section for mini Host mini User root RemoteForward 8377 localhost:...
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How to make a port open?

When I ping, there is reply. $ ping 10.26.14.16 64 bytes from 10.26.140.160: icmp_seq=1 ttl=63 time=0.525 ms When I ping with port, there is no reply. $ nmap -p 5016 10.26.14.16 5016/tcp closed ...
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