Questions tagged [port]
The port tag has no usage guidance.
191
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Port forwarding OPENVPN to one client (ip changes)
I just installed openvpn on Ubuntu and need to forward specific port to a client. This client is not on LAN and changes ip dynamically. How can forward traffic to a specific account connecting to my ...
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2
answers
16
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docker exposed port not accessible from outside even when port is opened using iptables command
I have a sample docker tar image in my linux based server and ran that though docker run command as below where 9521f101839f is image id.
docker run -p 0.0.0.0:9895:9898 -td 9521f101839f
So now ...
- 101
0
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1
answer
29
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Socat specify source port
How do I specify source port in socat?
In netcat I can simply:
nc -u -s 192.168.0.1 -p 8888 192.168.0.2 9999
I tried
socat udp4:192.168.0.2:9999 STDIN:192.168.0.1:8888
It's failed
STDIN: wrong ...
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41
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How does a telegram bot work in Linux?
I wrote a simple telegram bot and it works great without conflicting with my firewall. But my question is this, in the firewall I have ports 80 and 443 allowed for my site, but when I write a TCP ...
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81
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Unable to connect to a listening tcp port 80, Iptables is not blocking it
I am trying to see if tcp port 80 is open on a debian 11 server. I logged into it using SSH and did curl -v telnet://localhost:80. It says connection refused. If I do the same with port 22, it shows ...
- 375
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19
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How can I make a port inside a virtual machine accessible to the host if the virtual interface has its traffic forwarded through a TPROXY target?
I have a virtual machine connected to virtual interface that has all its traffic sent through a TPROXY transparent proxy:
ip tuntap add tap0 mode tap
ip link set tap0 up
ip addr add 10.0.0.1/24 dev ...
- 131
0
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2
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48
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Check what service is running on a specific tcp/udp port
I'm looking for a command-line utility that allows me to check what service (eg: http/ftp/ssh) is running on a specific port of a remote machine.
An example of how I imagine a program like this would ...
- 103
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1
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36
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forward outgoing port and sourcenat this traffic
I have crawled the internet, and tried some config, but so far, i am stucked, so i would need a little help if someone has a better experience than me on this. :)
I got a server,server1, behind a ...
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1
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31
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Port forwarding 3389 into local network safety
I've installed xrdp on a system running centOS7 - this allows me to rdp from any pc on the network using the local ip/hostname. I'm looking to be able to rdp straight into the system from outside of ...
1
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1
answer
20
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If ports are unpriviledged, why can't I access them if I am root in a namespace?
I've run sudo sysctl -w net.ipv4.ip_unprivileged_port_start=1. However, sudo ip netns exec myvpn unshare -r python -m http.server -b 127.0.0.1 2 does not work. Strangely enough, this does: sudo ip ...
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25
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What does the ss output's port number for a unix domain socket mean?
For example, the 15240 below,
# ss -xpl | grep stdout
u_str LISTEN 0 4096 /run/systemd/journal/stdout 15240 * 0 users:(("systemd-journal",pid=254,fd=5),("systemd",pid=1,fd=...
- 505
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1
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34
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Cannot connect to other instances within an AWS LAN
My client installed several AWS instances, all in the same region/datacenter.
My task is to install a Redis and a Postgresql instance on one of the machines and make the data store/database accessible ...
-1
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2
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100
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how to Find the port number according to PID [duplicate]
The following command can be used to find out which process is listening on a particular port:
netstat -ltnp | grep -w ':8011'
How can we do the opposite, find the port number according to PID ...
- 11.4k
1
vote
1
answer
78
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iptables not blocking access via ports?
I'm running Debian 8.11 with iptables v1.4.21 and ipset v6.23, protocol version: 6.
I'm trying to block access to certain ports for all but a small set of hosts, but it doesn't seem to be working.
...
- 405
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1
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298
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Serial port to COM port - no output found
I am using Ubuntu WSL1 in Windows. I want to find my serial port which is currently connected on COM4 and I am running this command:
dmesg | grep tty, dmesg | egrep tty, setserial commands, but ...
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1
answer
67
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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 ...
- 405
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0
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753
views
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: ...
- 7
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1
answer
43
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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.....
- 429
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1
answer
61
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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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1
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4
answers
199
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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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334
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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
...
- 111
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71
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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 &...
0
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1
answer
114
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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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1
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42
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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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0
answers
793
views
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
...
- 101
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149
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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 ...
- 419
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0
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941
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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 ...
- 113
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1
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308
views
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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52
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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 | ...
- 4,512
3
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1
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450
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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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1
answer
138
views
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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1
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0
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57
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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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4
votes
1
answer
155
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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 ...
- 4,512
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0
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31
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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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1
answer
430
views
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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0
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25
views
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 ...
-1
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1
answer
249
views
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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2
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699
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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 ...
- 105
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242
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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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1
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129
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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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1
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1
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166
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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
554
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 ...
- 721
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362
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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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84
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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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232
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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
...
0
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2
answers
239
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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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48
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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
533
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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1
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401
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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 ...
- 7,683
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0
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39
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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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