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Questions tagged [firewall]

a technological barrier designed to prevent unauthorized or unwanted communications between computer networks or hosts

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How to match the --out-interface to the same --in-interface in iptables

The system have multiple interfaces: eth0, eth1, eth2, ... br0, br1, br2, ...etc. The following rule will allow packets from "br0" to "br0": iptables -A FORWARD -i br0 -o br0 -j ...
stackbiz's user avatar
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Cannot establish HTTP connection with VPS although ufw is allowing outside traffic

Here is the output of sudo ufw status verbose Status: active Logging: on (low) Default: deny (incoming), allow (outgoing), disabled (routed) New profiles: skip To Action ...
Soham Jobanputra's user avatar
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Why Ubuntu 22.04 Network Manager sends messages to blackcat.canonical.com in two IP addresses?

Here are the netstat -tnp output captures from my Ubuntu 22.04 workstation. Why are there outbound NetworkManager connections established from time to time? What are they doing? The IP addresses ...
IpSmile's user avatar
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Ping IP Linux Ubuntu

PT-BR Estou utilizando Ubuntu e preciso descobrir a latência de um IP de um subdomínio. Tentei primeiramente o comando "ping", mas sem sucesso. Também tentei chegar se a porta 53 e 80 ...
Eric Mateus's user avatar
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Firewall to white- or black-list incoming requests

Well over a decade ago, when I was a Windows user, I used a Kaspersky firewall that would pop up when an application wanted was receiving a connection and allow me to allow or deny such connections. ...
Kohjah Breese's user avatar
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Disable Internet access but allow chrome extension

I'm trying to deny access to the Internet and that part works with ufw default deny outgoing (the PC is going to be used for exams so no googling allowed;-)) But I need access to a chrome extension ...
Kevin Petersen's user avatar
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SSH not working on port22 after checking open port, updating UFW, port fowarding on router and confirming internet carrier ports status with carrier

This is my first time trying to make an SSH tunnel. The purpose is to make an offsite backup our server (server A) in the office which is about 1 mile away. I have set up all ports on the office ...
Tyran Mincey's user avatar
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2 answers
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Portforwarding Port 22 ( for ssh ) over JioFiber Router not working ( port 22 is closed )

I am using a JioFiber Router ( Firmware version : SRCMTF1_JCOW414_R2.52.1 ) . The host that I want to expose to the internet has Ubuntu Server 24.04. Private IPs : Router ...
ubuntu-server-noob's user avatar
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UFW not logging [UFW BLOCK] events when default is to allow incoming connections

I'm trying to get a message logged to /var/log/ufw.log when blocking packets. It's all working very well, until I change the default behaviour for incoming connections. I use ufw default allow ...
Alejo Flores's user avatar
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Firewall ufw to deny port visibility

How can I block ports from being visible/accessible from the outside using ufw? If I nmap my server I can see all my running Docker containers (all ports from 8080 to 8086), which I do not want, ...
Socrates's user avatar
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Cannot start Ubuntu on WSL2

have a W10 device in test environment with clean WSL2 install, no distros. Installed Ubuntu. When attempting to launch I receive the error: WslRegisterDistribution failed with error: 0x80072749 Error: ...
user3272124's user avatar
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iptable-save command not showing any output

When i run iptables-save command on Ubuntu Ubuntu 22.04.3 LTS and Ubuntu 20.04.4 LTS it not showing default firewall chain rules when i run this other linux example centos or redhat i am able to see ...
Vishal Kharade's user avatar
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AXIOS/Fetch - Error on Ubuntu

Axios or Fetch data from external API Error on Ubuntu 22.04, but if using local API or try on my Windows, it can work.
Muhammad Arizky's user avatar
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Ports show as open when nmaping to localhost but filtered when connecting to IP

My 22.04.4 Ubuntu server was installed on a Proxmox VE. Then I installed Discourse forum on top of it (it uses Docker). Now, after successful installation the Docker's 443/80 ports show as closed when ...
Marek Wojtaszek's user avatar
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How to allow direct connection to plex media server

im trying to set up plex media server on ubuntu server os. i installed the plex media server and when im trying to watch in the same network everything is ok. the problem starts when i try to stream ...
user23887851's user avatar
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Graphic Issues Firewall gfuw in Ubuntu 22.04.4 on RPI4 8GB

I'm running ubuntu mate 22.04.4 LTS on my 8GB Raspberry Pi 4. After not using the device for some weeks I ran all updates and upgrades. I noticed that the VNC remote access was no longer working so I ...
snastro's user avatar
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Jammy 22.04 Attaching a pro subscription

when I try to attach my UbuntuPro subscription it keeps failing with no real error message. lsb_release -a No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu 22.04.4 LTS ...
Greg D's user avatar
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Unable connect via port knocking

I am trying to set up port knocking on my server to enhance security. I've configured my firewall rules to use port knocking, where I have to connect to specific ports in a specific sequence before ...
noobintech's user avatar
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LAN network with just two computer: All ports time out, except port 50002, which refuses connection. Why?

Preface and Context: I am currently troubleshooting the ROS2/LAN based connection of my UR5 CB3 robotic arm with the Ubunut 22 control comupter and the respective driver. This robotic arm seems to ...
Padit's user avatar
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Assistance Needed: Recovering Root Password and Accessing Firewall Settings on Ubuntu 20.04 Server

I am encountering issues with my Ubuntu 20.04 server running on Oracle, as I have forgotten the root password. Unfortunately, I am unable to access the GRUB menu to initiate password recovery. Could ...
ahmed metwali's user avatar
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Why tor need icmp in outbound iptables?

I'm trying to block everything in outbound except tor with iptables. But without enabling icmp tor doesn't work, it's very strange since tor don't use icmp as my understanding. That's what I'm using ...
March Lagos's user avatar
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firewall is enable but gufw wont lauch

The firewall is enabled. But I can't launch gufw interface. sudo ufw status Status: active
kalpa's user avatar
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Port not open (ufw disabled)

On the server, running Ubuntu 22.04 sudo netstat -tnlp | grep :4000 tcp 0 0 0.0.0.0:4000 0.0.0.0:* LISTEN 10690/nxd tcp6 0 0 :::4000 ...
Jasmeet Singh's user avatar
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535 views

How to open port on wsl2 ubuntu of windows 11

To test the network between Windows 11 localhost and WSL2 ubuntu on Windows 11, I install tomcat9 on WSL2 ubuntu $ sudo apt install tomcat9 -y $ sudo systemctl enable tomcat9 $ sudo systemctl start ...
Joseph Hwang's user avatar
-1 votes
1 answer
2k views

Use UFW (firewall) to deny incoming ping (ICMP) requests?

The ufw (uncomplicated firewall) command line app does not have any option for disabling incoming ICMP Internet protocol requests. ICMP is used mainly by ping to discover IP addresses of servers on ...
hobs's user avatar
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209 views

Connection refused from localhost in wsl2 ubuntu

I try to test connection between windows 11 and wsl2 ubuntu in windows 11. First I install nginx on wsl2 ubuntu and type in 'localhost' on web browser on windows 11 . The connection is successful. And ...
Joseph Hwang's user avatar
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1 answer
80 views

ufw won't put custom rule in the correct place at reboot

My general issue is that I lose contact with my Ubuntu 23.10 on ssh once I close my ports using knockd. I would like for it to maintain existing connections. I have a custom rule > iptables -I ...
brad's user avatar
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Specify L2TP VPN to use other port

I am currently at a hotel and they seem to block VPN use. I assume they block it by looking into the port it uses. I would like to use my company VPN (L2TP). So, I think my best bet is to change the ...
Darren Christopher's user avatar
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How to enable communication between 'software' netplan configured vlans

I have searched far and wide so I if it looks like I have no idea what i'm doing, that is because it is a correct assumpstion. Usually we do this ourselves with our MikroTik router setup. We have a ...
Nejc Robnik's user avatar
1 vote
1 answer
136 views

What are the use cases of "continue" verdict in the nftables?

It is described in the documentation of nftables as: continue Continue ruleset evaluation with the next rule. This is the default behaviour in case a rule issues no verdict. But I am ...
Noah5CE's user avatar
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2 answers
281 views

LXC container cannot ping 8.8.8.8 or other outside ip

I run a LXC container on my "Ubuntu 23.04" VM by UTM on my mac laptop but I cannot ping 8.8.8.8 in my LXC container. I downloaded lxc via snap note: I have search many info to fix the ...
Harris's user avatar
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0 answers
47 views

Checking this network connection (port forwarding)

I have the below setup, I want to be be able to reach the device (192.168.2.180 eth) from my desktop (192.168.1.3 wifi) I have a linux server in the middle (192.168.1.111 WIFI), (192.168.2.22 Eth) ...
Tam's user avatar
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1 answer
270 views

Using Ubuntu 22.04 as DNS Server with bind9

I want to use a simple ubuntu 22.04 server as a DNS Server for my pc. I created a new server, with a static ip address, that i will type in to my dns in windows. My problem is, when i try nslookup ...
jelkaa's user avatar
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3 votes
3 answers
316 views

Having issues locking down public server with iptables

I'm rather new to Ubuntu. I'm trying to lock it down to where I have complete access to it from my ip address and everyone else only has access to port 80 and 443. To better understand it, I put my ...
ErocM's user avatar
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112 views

Why I lost my internet connection when in windscribe console I set “Firewall” option "On"?

I have installed windscribe on my kubuntu 22.04 but when I run windscribe console and set “Firewall” option on - I lost my internet connection. I think the reason could be that I have windscribe ...
mstdmstd's user avatar
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1 answer
323 views

vsftpd fails LIST command even when firewall is off and on localhost

I installed vsftpd and am using ufw as my firewall. I can connect to the ftp server, login, and change directories, but any attempt at using a LIST command times out from both external and localhost. ...
joebird's user avatar
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0 answers
192 views

ufw rule to allow address on the same subnet?

I have a server running Linux hosting a website. It uses ufw as a firewall. I have ports 80 and 443 open to external traffic. This all works. Now what I want to do is allow any traffic from my laptop ...
Mark Challice's user avatar
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128 views

Still getting [UFW BLOCK], which rules apply?

I still get a message UFW BLOCKED: Dec 22 05:12:41 ge-domoticz kernel: [5324365.003868] [UFW BLOCK] IN=eth0 OUT= MAC=b8:27:eb:a1:7b:8b:38:1f:8d:e9:e4:9f:08:00:45:00:00:28:92:8c:00:00:ff:06:2f:d4 SRC=...
Edgar Hildering's user avatar
0 votes
1 answer
257 views

Port Forward for LAN

I bought a server and have Ubuntu 22.04 installed. When I run various Github projects like Text Generation Webui, Automatic1111 Stable Diffusion, etc., how do I forward the port to access it from my ...
rbur0425's user avatar
  • 103
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0 answers
157 views

Ubuntu 23.10 keeps inconsistently blocking incoming connections (from machines on the same subnet)

I have a fresh install of Ubuntu 23.10. It's running on a PC at home, and is only Wi-Fi connected. I've enabled ufw, and have allowed web traffic as I'm using this to mock up a Wordpres site for ...
Chris Millard's user avatar
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nginx running and port allowed, but on client side is closed

I have a server was running fine with port 443, but not it's not running. using command sof -i -P -n | grep LISTEN, i get: nginx 3124 root 6u IPv4 39437 0t0 TCP *:443 (LISTEN)...
mohamad zbib's user avatar
2 votes
1 answer
532 views

3proxy, plain HTTP proxy, "Failed to connect"

I'm trying to configure 3proxy on Ubuntu 22.04, following the instructions on the developer's website as well as tutorials from the internet. I need a standard HTTP proxy. All HTTP and HTTPS ports are ...
Anatoly Frolov's user avatar
0 votes
2 answers
469 views

Cannot access any service running on ubuntu server including SSH

Problem: I'm unable to access any service running on by Ubuntu 22.04, including SSH. This server has been running for months without any issues. It currently hosts a frontend as well as 3 different ...
arsenal_fan_2004's user avatar
1 vote
0 answers
95 views

Strange UFW Block Logs

i noticed repeats of the following logs in my server: Dec 3 21:55:27 alice-server kernel: [287677.084885] [UFW BLOCK] IN=ens18 OUT= MAC=01:00:5e:00:00:01:90:9a:4a:dc:31:62:08:00 SRC=192.168.0.1 DST=...
James's user avatar
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0 answers
348 views

Ubuntu 22.04 iptables command not working

I posted this same question in another SE forum, later felt this forum is more appropriate considering the Linux Distro I am dealing with. Totally new to netfilter thing, currently am running an ...
RaGa__M's user avatar
  • 101
2 votes
1 answer
565 views

Strange dmesg UFW messages... lots of them

I've done some digging but haven't been able to find something that explains below message I found in dmesg? It's obvious the UFW firewall is blocking something, but I am not having any success in ...
GregoInc's user avatar
  • 111
0 votes
0 answers
30 views

I'm attempting to execute a Flask test file, but when attempting to access it through the browser, an error stating that the site cannot be reached

I have tried creating an inbound rule in my firewall to allow port <5000> but its still showing site cannot be reached. i have also tried to Check UFW (Uncomplicated Firewall) with this command '...
era's user avatar
  • 1
1 vote
1 answer
213 views

Can access self-hosted Portainer website from internet trying to lock server down without any luck

I'm new to Docker & Portainer and I'm trying to lock it down from public access where it's not needed. My setup: Windows 2022 Server running Hyper-V (host) Ubuntu 22.04 Workstation (virtual ...
ErocM's user avatar
  • 521
1 vote
1 answer
178 views

Can only access some servers on Linode VLAN

I am running a VLAN applied to a number of servers on Linode. The IPs assigned are 10.0.16.n/24 and are accessed via an OpenVPN server also on the same range. I have connected to the VPN box from my ...
Antony's user avatar
  • 279
0 votes
1 answer
250 views

The download manager loses its access to the Internet after working for a while in ubuntu 23.10.1

I use download manager in Ubuntu but after a while it works fine and the internet access is blocked! I tested Free Download Manager and Xtreme Download Manager both of them at first work correctly but ...
mamad2559's user avatar
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