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Questions tagged [ufw]

Uncomplicated Firewall (ufw) is a frontend for iptables, works as a host-based firewall and provides a framework for managing netfilter, as well as a command-line interface for manipulating the firewall.

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VPN kill switch with UFW

You all probably heard of Tunnelvision attack on VPN's. Basically, it is about this: the attacker in rogue LAN abuses DHCP option 121 to set a route on the VPN user’s system that is more specific than ...
Matthai's user avatar
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Tracing iptables Rules

I'm just beginning to dig into iptables for the first time today, so apologies for any naivete. For reference, I'm using Ubuntu 22.04.4 LTS (Jammy Jellyfish) iptables v1.8.7 (nf_tables) ufw 0.36.1 ...
ALittleHelpFromMyFriends's user avatar
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What configuration is blocking local ssh connections to my server?

So I recently bought a Raspberry Pi to work on a small passion project with the RetroPie Debian-based image. I am now at the stage where I want to completely shield the server only allowing specific ...
Ress's user avatar
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Many UFW BLOCKs pr minute from numerous ports and numerous IP addresses

My syslog is flooded with numerous attacks of some sort coming from multiple sources. I looked at all the other references in the search feature but none addressed tcp and from numerous sources Feb 16 ...
brad's user avatar
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GUWF and firewall malfunctioning?

I keep adding IP addresses to the built-in Linux Mint "firewall" program (which is "GUWF" relabeled "firewall") and it worked for a while ... but now it doesn't look like ...
natS's user avatar
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Ubuntu 22.04 iptables command not working

Totally new to netfilter thing, currently am running an application which uses three interfaces eth0/eth1/eth2, my application will run on two servers and they both can communicate between them via ...
RaGa__M's user avatar
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393 views

I am unable to access my HTTP NGINX server over LAN

I have allowed the port in ufw and have the following configuration: server { listen 0.0.0.0:8000 default_server; server_name _; index index.html; access_log /var/log/nginx/html....
RadoslavL's user avatar
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ufw rule supposed to block traffic but iptables allows it

As a test I wanted to temporarily block access to my website. So, I deleted http/https rules using ufw delete command. ufw is set to default deny incoming. The only remaining rule is the one allowing ...
Faxopita's user avatar
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1 vote
2 answers
212 views

Installing ufw as root vs installing using sudo

Is there any security issue if I installed ufw as root instead of a non-root user using sudo? I checked Not installing as root but the answer related to what I am installing as I understand.
MAMProgr's user avatar
  • 111
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1 answer
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How to define port forwarding

I run a server with a web server running as a rootless podman container. This exposes ports 10080 and 10443 because, as a rootless container, it is not allowed to expose ports 80 and 443. So that my ...
M.Ede's user avatar
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UFW Active but Not Enabled After System Reboot in AlmaLinux 8.8 (Sapphire Caracal)

I'm encountering an issue with UFW (Uncomplicated Firewall) on my Linux system. After a system reboot, when I check the status of UFW using the ufw status command, it returns that the firewall is ...
Abdulhamid's user avatar
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I can't block a port with ufw

This morning I received a report from Netscan: Netscan detected from host 8X.19X.1X.1XX time protocol src_ip src_port dest_ip dest_port Fri Sep 15 05:21:59 2023 UDP 8X.19X.1X.1XX 5065 => 9.87.179....
Willy Makend's user avatar
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1 answer
93 views

IPV6 local UFW BLOCK syslog

The log in syslogs is as follows: [UFW BLOCK] IN=wlan0 OUT= MAC=33:33:00:00:00:01:e8:48:b8:5f:a0:e8:86:dd SRC=fe80:0000:0000:0000:ea48:b8ff:fe5f:a0e8 DST=ff02:0000:0000:0000:0000:0000:0000:0001 LEN=52 ...
Yeh acc's user avatar
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1 answer
3k views

UFW Couldn't determine iptables version

I am building a custom embedded Linux platform based on the NXP i.MX8 with Yocto. I want to use UFW to setup the firewall. When I boot the system and try to use UFW it returns an error Couldn't ...
PhilBot's user avatar
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1 answer
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Firewall : firewalld with docker open port for local service

I'm trying to open port for ssh on non-standard port like 12452, i used these commands and non of them worked iptables -I INPUT -p tcp --dport 12452 -j ACCEPT iptables -I OUTPUT -p tcp --dport 12452 -...
Ebrahim Karimi's user avatar
1 vote
1 answer
703 views

How to safely open ports in ubuntu 22.04 for Cyber Protection Agent

In Ubuntu 22.04, I have installed the Backup Agent for Linux Servers "Cyber Protection Agent" on vps. I have followed this link https://www.ionos.com/help/server-cloud-infrastructure/cloud-...
hous's user avatar
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190 views

Blocking ssh bruteforcers with ufw

I want to block SSH brute force attacks using ufw. Here is the code to block them: Citing "The Hail Mary Cloud And The Lessons Learned: BSDCan", it could be done: By pf: table <...
somenxavier's user avatar
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Why do I have log-entries in `/var/log/ufw.log` while my laptop was in standby?

While debugging a network related issue I found these entries in /var/log/ufw.log: $ tail -f /var/log/ufw.log Jun 22 00:07:55 ierbert2 kernel: [217764.254528] [UFW BLOCK] IN=wlp59s0 OUT= MAC=9c:b6:d0:...
packoman's user avatar
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Enable NAT with TCPMSS using UFW

I could enable NAT using UFW with following configuration. *nat :POSTROUTING ACCEPT [0:0] -A POSTROUTING -s 192.168.141.0/24 -o ens192 -j MASQUERADE COMMIT If I want to enable TCPMSS, I have to run ...
yananet's user avatar
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1 answer
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Cannot connect to wifi hotspot while vpn is turned on

I am using warp-cli (cloudflare vpn) and after I enable the vpn, I cannot connect any new devices to the wifi-hotspot. Existing connected devices stay connected while vpn is turned on but no new ...
Tuhin Garai's user avatar
1 vote
2 answers
235 views

UFW not blocking connection

I am using the Cloudflare IPv4 and IPv6 lists to block all connections to my server from any IP that is not owned by Cloudflare. When I run sudo ufw status on the server I get: Status: active To ...
Just a nice guy's user avatar
5 votes
0 answers
1k views

Ubuntu 22.04 firewalld initiation problem: no python-nftables

I tried to use firewalld instead of ufw, but it keeps showing the following errors even after manually downloading python-nftables through sudo apt install iptables is not being used. $ systemctl ...
Nimbus's user avatar
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1 answer
547 views

UFW Block in Syslog - Why are many different IPs trying to connect to my server

first of all I want to clear up that I'm not a network expert and just trying to understand things. I hope I can find help here and get a bit smarter.. I'm hosting a service on a Ubuntu 22.04 vps. ...
mojo_x's user avatar
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0 answers
638 views

UFW apparently causing SSH to timeout despite specific rule

I'm new to SSH and ufw and would like to understand why one type of rule works between two Linux Mint computers on the same home LAN but another does not seem to work. I just wanted to allow one ...
Puffin's user avatar
  • 101
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0 answers
219 views

Uncomplicated firewall UFW unintentionally blocking traffic

On a web server (VMware-VM with Ubuntu 18 LTS) with an (externally firewalled) IPv4 address, I did apt-get install --no-install-recommends ufw ufw deny from <some chinese hacker IP> to any # ...
Juergen's user avatar
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0 votes
1 answer
947 views

UFW not fully loading rules on startup

I have a server with default deny and several UFW rules. UFW is enabled on startup (systemctl enable UFW). When I reboot only some of the rules don't get applied properly and I can't access some ...
Mike's user avatar
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1 vote
1 answer
214 views

UFW BLOCK on syslog

I was able to see this "UFW BLOCK" in Syslog at different times. Dec 15 01:22:23 node1 kernel: [4837640.303204] [UFW BLOCK] IN=enp4s2 OUT= MAC=xx:xx:xx SRC=192.168.x.x DST=192.168.x.x LEN=...
Janitha Dilshan Siripella's user avatar
1 vote
1 answer
284 views

How to link Ausweisapp2 with Smartphone app

I cannot link my Ausweisapp2 to the app on my smartphone (app for german eIdentity service). Installed via snap: sudo snap install ausweisapp2-ce In the app, there are no available devices shown. ...
pLumo's user avatar
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1 answer
2k views

Why can't apt find my desired version of iptables?

I am trying to install version 1.6.2 of iptables in ubuntu 22.04. (Please note: This is about iptables 1.6.2. I have no trouble installing iptables 1.8.7, but I need 1.6.2.) root@924516f76c4c:/var/...
arnoldbird's user avatar
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1 answer
285 views

UFW seems to be ignoring allowed ports in specific cases

I've got a Raspberry Pi set up with UFW firewall to try and secure it as best as possible. Most of the rules seem to work absolutely fine, but for some reason, it's blocking specific connections which ...
BallistiX09's user avatar
1 vote
2 answers
184 views

Are these attack attempts to my PC stopped by ufw?

The router re-directs several ports to my PC. I checked ufw.log and found many entries that look like attacks from other countries. I checked the IP and they are reported as abusive/ hacking. These ...
daniel_hck's user avatar
2 votes
1 answer
653 views

Why am I locked out of my machine with these ufw rules?

I have a server on ip 192.168.1.200 My goals are: I should be able to log in to my server via port 22 from anywhere From inside 192.168.1.200 I should be able to access the Internet via ports 443 and ...
Duke Dougal's user avatar
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1 vote
0 answers
55 views

Uncomplicated firewall - DEFAULT_FORWARD_POLICY implications?

I don't understand what the function of DEFAULT_FORWARD_POLICY. Is using ACCEPT considered a security risk, if so, why?
user_968563's user avatar
1 vote
1 answer
1k views

Why is UFW blocking acces to SSH via Wireguard?

192.168.100.50 is connected to 192.168.178.20 over the internet via wg0 interface. wg0 is opening up the tunnel 10.102.242.1/24. The wireguard client interface has 10.102.242.2. Through a static route ...
bomben's user avatar
  • 509
1 vote
1 answer
838 views

Weird network traffic on Ubuntu 22.04

I noticed abnormal network activity when trying to test something and I can't find what program is the culprit. Wireshark: My local IP is 192.168.100.5 I tried to inspect with sudo netstat -latpen ...
weirdnoddle's user avatar
1 vote
0 answers
153 views

Prevent network namespaces / lxd-bridges from talking to each other, but keep internet access?

Following goal: I have lxd containers each set of containers should have their dedicated isolated network each should still be able to connect to the internet (e.g. apt update or curl), but not leak ...
stackbox's user avatar
1 vote
1 answer
2k views

ufw blocks communication between docker containers

I have setup two docker containers for a Magento instance and a redis instance. For now, I only want to allow certain IP addresses to access the website, so I enabled ufw and added some entries. The ...
Comforse's user avatar
  • 630
1 vote
1 answer
682 views

Which process is sending outbound requests?

I recently installed a Ubuntu desktop (only additional programs being google-chrome and VLC). When I enabled UFW and blocked everything outgoing by default, I noticed a bunch of outgoing attempts ...
Dr Phil's user avatar
  • 139
3 votes
1 answer
2k views

Opening a protocol (112, vrrp) with Ubuntu 20.04 ufw to allow multicasting

I've been installing keepalived on my Ubuntu 20.04 box however for VRRP to work (using multicast) I need protocol 112 opened up on the firewall (note this is a protocol, not a port). From everything I'...
Marcos's user avatar
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0 votes
1 answer
527 views

Redirecting DNS querries from NAT'd devices and UFW

I'm having a tough time figuring this one out. I have the following network: (Internet)--(firewall) -- (PC1 (Ubuntu 20.04)) -- (PC2 (Fedora, 192.168.0.2)) PC1 has two NICs, (enp4s0) faces the firewall,...
Fratink's user avatar
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2 votes
1 answer
7k views

ufw "command not found"- but as the root user!

My Debian 11 VPS is running now for about 2 weeks- and today I just wanted to analyse, why my traffic is ~70GiB (counted by bashtop). So somewhere in the net I read about nethogs, that this could help....
ubuntu4life's user avatar
1 vote
1 answer
3k views

Why am I getting connection refused with IP address even though it works with localhost and firewall is open?

When I run sudo ufw status on a Ubuntu box, I get the following output sudo ufw status Status: active To Action From -- ------ ---- 22/tcp ...
Finlay Weber's user avatar
2 votes
1 answer
5k views

How to tell which application UFW is blocking

I have a Debian system running ufw. I have "default deny" on all outgoing connections and I open specific communications (ports and/or IP addresses) as needed. I use the dmesg log to see if ...
bitsmack's user avatar
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0 votes
1 answer
294 views

Meaning of fields in ip6tables logs

I am parsing ufw logs, and running into limitations with the documentation that I am able to find for the ip6tables entries for ufw. This very nice blog post describes the iptables format well, but ...
Jennifer's user avatar
0 votes
1 answer
3k views

UFW Masquerade and outside traffic only on specific interfaces

I have a Ubuntu system (192.168.A.B) that is running as a Wireguard "server" with 2 tunnels with the following networks and UFW rules: Network 10.255.200.0/24 ufw allow XXX/udp && ...
MorRich's user avatar
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1 vote
0 answers
157 views

UFW is Manually Disabled via Shell - Can the system re-enable it on boot?

Take note i am already aware how to have start the ufw service on boot. This is not what i am asking. So, right now, if i check ufw status it shows as "Active". And when i reboot and check ...
The Stare's user avatar
1 vote
1 answer
171 views

Why does traffic continue to flow through my gateway despite a firewall rule blocking all outbound traffic addressed to it?

While messing around in a qemu guest I discovered something very peculiar. If I set the system firewall to reject all traffic to my gateway (10.0.2.2), the firewall only rejects traffic destined to ...
Tenders McChiken's user avatar
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0 answers
3k views

Cant connect to my tigervnc server hosted on Ubuntu 20.04.4 LTS

Did some basic debugging. VNC session is created vncserver -list TigerVNC server sessions: X DISPLAY # RFB PORT # PROCESS ID :1 5901 4479 Port 5901 is enabled in firewall sudo ufw ...
tr1via's user avatar
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0 votes
2 answers
2k views

ufw not logging all connections as expected

I am trying to setup logging on ubuntu server 20.04.4 using ufw, but I'll take non-ufw advice as well. I am running a test https server on port 20000 and want to log all connections to it. Here's what ...
Dr Phil's user avatar
  • 139
0 votes
1 answer
495 views

Setting up Port forwarding on Ubuntu 21.10 with OpenVPN (homerouter port forwarding not working)

I'm trying to setup port forwarding on my local workstation, since the home router is not capable of doing the port forwarding I went on with privateVPN. The privateVPN is configured on OpenVPN with ...
avman's user avatar
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