Questions tagged [firewall]

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

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27 views

Having to reopen ports on reboot

When I restart my computer I keep having reopen ports using iptables. Using a "UFW allow" doesn't open the port and isn't persistent. Pertinent info 20.04 Was troubleshooting a LAMP stack ...
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Unable to add rules to /etc/ufw/before.rules and before6.rules

I run a high-traffic NTP server and the following rules are absolutely necessary to prevent my conntrack table from being immediately overrun (regardless of how large it is): iptables -t raw -A ...
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iptables - help me figure out if my forwarding scheme is correct?

I want to forward everything from wlan0 to tun0, and everything from tun0 to wlan0. Using sudo iptables -S command, the output is:(assuming this is the actual rule of my iptable) -P INPUT ACCEPT -P ...
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Should I use another computer, to block my real IP address? [closed]

Please tell me how to stop VM, Scripts, Forced drivers injections(not possible to delete). SSH? Should I use another computer, to block my real IP address? Changing my files, displacing them around ...
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iptables port forward to diferent box port

Hy everyone! I have a home network, and have a DVR (provison) connected with my cameras. I can access to my dvr via internet/lan, but the dvr don't have any security options except fixed ips or ip ...
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why does UFW block ICMP destination-unreachable messages despite apparently having rules to allow them?

Ubuntu 20.04.2 LTS, I am running UFW with mostly default configuration, have allowed some ports through with "ufw allow" but haven't done any manual blocking or config files editing. I was ...
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Webmail behind firewall

I hope someone can point me to a guide or help set up a mail server behind a pfSense firewall that would be separated from the web page. I am a relative newbie on Linux, so the more detailed, the ...
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difficulty starting samba on ubuntu

I'm having difficulty starting samba on ubuntu How can I see what ports are open on my machine? root@ubuntu-s-1vcpu-1gb-intel-nyc1-01:~# sudo netstat -ntlp | grep LISTEN tcp 0 0 127.0.0.53:...
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Ufw blocks incoming and outgoing connections

To update firewall rules, reloading ufw ufw reload blocking incoming and outgoing connections for around 2 seconds, untill it completes reload process. I have set already the default policy deny for ...
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IPTABLES/UFW: Deny ssh (on alternate port) requests from WAN, and allow ssh (on alternate port) from LAN. HOW TO?

I am running Ubuntu server version 20.04. I have configured my ssh server to listen on an alternate port (port 40001) in my sshd_config file. I want to allow incoming traffic from anywhere on my local ...
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iptables - firewall configuration - Ubuntu Script 18.04

I need help with configurating iptables. I've made some progress which i think might work like, but i'm not sure. Looks like this: #!/bin/bash #changes NET="10.10.10.0" ADMIN="10.10....
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Bad argument `DROP' iptables

i have question i need help question is Build a firewall to filter traffic between two networks (Network A and Network B). Please note that you need to use the FORWARD chain. Please consider the ...
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SSL certificate only works on a port

I use an SSL certificate from Letsencrypt and this worked for me forever. Today an error has occurred that the SSL certificate is not secure. I use webmin as Control Panel and when I access webmin ...
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UFW status is getting problem running iptables

I want to use UFW (version 0.36) but I get this error when running ufw status: ERROR: problem running iptables: Another app is currently holding the xtables lock. Perhaps you want to use the -w option?...
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Could not make connection from local machine to Ubuntu even after opening Firewall

I am trying to setup remote postgresql for my app on cloud, however the connection is refused from my local machine. Please note i am able to make SSH connection from my local machine using putty. But ...
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On a new Ubuntu Server 20.04 install I can't connect to anything via my local network, i.e. Ping, SSH, etc. what steps should I take now?

I have a fresh install of Ubuntu Server 20.04. It's been a while since I've used Ubuntu and I'm at a loss on how to troubleshoot this next. My goal is, I'm trying to install Octoprint. I have it ...
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20.04 firewall conundrum

I'm trying to share files on home network between two linux machines: host-A is Ubuntu 20.04, host-B is Red Hat. Samba worked well until distr. upgrade to 20.04. Now cifs mount from host-B reports &...
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Ubuntu 20.04 Open a Port

I use Nordvpn. I whitelisted port 8000 so that I access ajenti control panel, however nmap still shows that the internal / external IP addresses have port 8000 blocked. External IP Output $ nmap -sT ...
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Ubuntu 20.04 gateway, iptables NAT and port forwarding

i am in a maze, i try in vain to setup the rules to be able to acces from internet my internal web server (192.168.12.10). at home, i have an Ubuntu 20.04 gateway (192.168.12.1) with two interfaces : ...
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What are best settings for “System Configuration Module: Connections” with wired connection?

2 weeks old newbie here, 20 years Windows user. Still struggling a bit... I use wired connection: first I connected from computer to modem, but found in some posts that it's safer to use router (since ...
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ufw block error seen in journalctl -xe command

I'm newbie in networking and system security. I am trying to create openconnect server which tutorial is found in this link. I have also seen the similar issues like this one, but they don't make ...
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Cannot curl into a port

I have geth node (ethereum node) on a raspberry pi running ubuntu server 20.10 Unfortunatly I cannot access it through and other computer of the network, it will only work inside localhost. So I've ...
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SSH tunneling blocked on 20.04 LTS?

I tried using Hamachi to play with a friend and he told me there was a vpn error next to my name. We could not connect at all and I tried everything to fix it. According to this website https://...
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Is there a firewall that returns html instead of just rejecting the incoming HTTP request?

Is it possible to return an HTML response like below instead of just rejecting the connection: You are bared from accesing this IP I understand there are ways to filter the incoming IP addresses at ...
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Port-forwarding for a minecraft server on 20.04 LTS

I've been trying to play with my friends online in Minecraft for a while now and the two methods I tried ended up failing. The first method was to use hamachi, however its tunneling engines couldn't ...
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antivirus and firewall software

I am using Ubuntu 20.04 and want to know if I need to install firewall/antivirus software. The "Similar questions" seem to all be outdated.
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Internet stops working on Ubuntu when opening any Torrent Client, but on Mac, It works just fine

This is how my network is set. I connect an iPhone 6 to Ubuntu via USB cable. The internet connection is fine until I open any Torrent Client App (Transmission, Deluge, etc). When I open any Torrent ...
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Cannot open port 3001 to local IPV4 ubuntu lts 20.04

I'm creating a back end app with NodeJs. My app running at port 3001. It is accessible when i try to access it with localhost:3001 or 0.0.0.0:3001 or 127.0.0.1:3001, but when I try to access it with ...
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Ubuntu Questions - Security - Concerns

I have a few questions that I would like to verify. I currently have a Ubuntu VM on my windows host. I am opening it up Port Forwarding so host a gitlab repo on it. I would like to be able to access ...
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Ubuntu firewall issue

I've broken my ubuntu's dns/firewall settings. I've installed toroxy and dnscrypt and after its deletion I don't have an internet connection even to my router. ping 192.168.100.1 # router address ping ...
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how to allow traffic on specific IPs for a port in iptables

I want to restrict traffic for all IPs except 10.2.3.4 on port 5041 First I gave access to the IP on the port like so : iptables -A IN_public_allow -s 10.2.3.4 -p tcp -m tcp --dport 5041 -m conntrack -...
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Ubuntu Router: Can't ping between two NICs

I'm quite new to networking and I'm simply trying to set up a robust router and firewall with my barebone Ubuntu 20.04 server. Consider the following setup of the NICs: enp3s0: IP: 192.168.1.23 ...
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Is it possible to create daily quotas for specific websites, based on duration of usage or data traffic?

I am wondering if some rule like the following can be set up at the router level; using iptables or ipset or similar tools. (I am not very experienced in this area, sorry if the following is a bit ...
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How do I only allow outbound connections to Cloudflare IP addresses?

I have a Ubuntu 20.04.2 LTS webserver that is behind Cloudflare. I have ufw rules to only allow connections from Cloudflare IP ranges, and I want to do the same for outbound connections. I'm looking ...
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What should I do if my server is under the attack?

I have a mail server on Ubuntu 20.04. Yesterday I set up UFW firewall which looks like: root@vmi514622:~# ufw status verbose Status: active Logging: on (low) Default: deny (incoming), allow (outgoing),...
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how to easily get all https addresses that an application connects externally?

for those who have a firewall with highly restrictive outputs, they only need to release supposedly reliable addresses for each application, so I was wondering if there is any software or command line ...
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I have a problem with SSH (or any port) I can't fix

I own a refurbished HP Proliant DL380 G7, for a small project I've been working on (It’s the first time using a server and setting it up). But after I set up Ubuntu 20.04 on it, the first thing I did ...
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How to forward all traffic between two ipsec tunnels?

I want to create vpn (IKEv2) tunnel with middle vpn server. Its should work like this schema - client -> middle (server A) -> output (server B). I'm using strongswan. This is my configs: ipsec....
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How to configure/test DPDK as software firewall

I have started exploring DPDK setup in Ubuntu. I am able to bind ports with DPDK drivers. I use Ubunutu 16.xx version in a virtual machine where the host is Windows 10. I want to use this vm as a DPDK ...
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SSH tunneling IP filtering

I have created this tunnel on server 10.1.1.1: ssh -f -N -o -L 8789:10.2.2.2:22 user@10.2.2.2 This allows me to connect from local server to the remote server, through port 8789, like so : ssh -p 8789 ...
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How to define rpcbind portmapper ports range to comply with a firewall allowed range

Having an rpc server running but rpcbind portmapper maps ports out of range allowed by firewall. Already tried to change ip_local_port_range but looks like it is ignored.
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Cant install anything with current iptables rules. What am I missing?

Heres my iptables rules below. I am trying to block everything except whats needed. I am not able to apt-get install with these rules. What am I missing? sudo iptables -F sudo iptables -X sudo ...
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No system network if docker installed on Lubuntu

The weekend past I lost the ability to access my media server which is a NUC running Lubuntu, took up until last night to realise docker was the cause, with docker installed the machine is basically ...
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Block a web address intermittently to reduce usage

I would like to arrange the restriction described in this scenario: User visits a "greylisted" website Access is granted and a countdown timer (e.g. ten minutes) is started After the timer ...
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Isolating bridged wifi networks

Borrowed a neighbour's WiFi with permission but trying to isolate them from each other. Ubuntu 20.04, receives WiFi from wlan1 (high powered + upgraded antenna alpha networks adapter) then uses ...
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Cannot open port on Ubuntu

What I want: Open port 19132 so it is reachable from the LAN. What I have: My home desktop PC runs Ubuntu 20.04.2 LTS. I have installed Minecraft Bedrock server which serves port 19132/UDP by default. ...
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firewalld not adding interface

On ubuntu 20.04 running netowrking and configuring the network using netplan, if i install firewalld i though that by default all interfaces are added to the public zone, but it seems like it is not. ...
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Lubuntu vs Windows 10 - default firewall - default settings

The results scanned from the third device connected to the same private network with the two devices in discussion, Lubuntu and Windows 10: The first scanned device, with Lubuntu(Ubuntu 20.04.2 LTS) ...
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Dunno how to ssh-connect to my vm

I installed ubuntu server on a vm(on virtualbox) on my computer. I want to access it from my phone which shares the same network as my computer. I have the openssh installed on my server and the port ...
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Ufw blocking packages that should be allowed in configuration

I have 2 servers running Ubuntu 16.04. Server 1 has ip 10.100.100.101 and server 2 has ip 10.100.100.102. Server 1 has Ufw enabled and should accept all traffic to port 8080 from server 2. (Server 2 ...

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