Questions tagged [firewall]

A Firewall is an application or hardware device used to inspect and filter network traffic.

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Is is possible to use OpenVPN client as default network gateway (OpenWRT)?

Usually, when using a VPN, you can route all client traffic(s) through a VPN tunnel with a exit point on the VPN server. Is there a reverse possibility: to organize an exit point to the WWW on the ...
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Firewall threat protection rules for SSH/SFTP

Can a firewall improve the security of an SFTP service through inspecting incoming requests (e.g. to block any SSH commands which aren't required when only using SFTP? Context I recently found a VM in ...
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How to avoid port duplication when using iptable for DNAT

I configure the iptable output chain DNAT conversion by the following command. iptables -t nat -A OUTPUT -p tcp --dport 5000 -j DNAT --to 10.100.1.10:2048 When I link 10.100.20.4:5000 on the client ...
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Windows server 2016 can't connect to remote port other than 80

I have a remote linux server running an HTTP service on a port 5000. I can use this service from my personal Windows computer with no problem, even connecting other remote servers is OK. However, my ...
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Firewall Ports Domain Controller to Clients

I am working on the segmentation of a network. Domain controllers and clients are located in different VLANs and are separated by a hardware firewall. Many ports must be opened for communication in ...
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How to block all outgoing SMB Traffic, with one exception by IP (Windows 10)?

Good evening. I am currently trying to prevent all SMB traffic on a Windows 10 Pro machine. However, I want to allow an SMB connection to a specific share based on the IP of the server. I have now ...
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nftables or fw4 issue with timebased traffic rules

Since the OpenWRT ver > 22.3 does use NFTABLES instead of IPTABLES I got issue with some firewall (fw4) time based traffic rules that I have no idea how to solve them. The firewall rule is as ...
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Why do I need extra rules that are the same as the default behavior in the iptables?

I am trying to understand the below iptables config file: *filter :INPUT ACCEPT [0:0] :FORWARD ACCEPT [0:0] :OUTPUT ACCEPT [0:0] # Allow WiFi AP traffic over 80 & 8080 -A INPUT -i p2p0 -p tcp --...
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how to disable public ip and make the external traffic flow through the private ip of the firewall

So, our requirement is to disable public ip of the node and then route the traffic through the private ip of the fortigate firewall. NOTE: eth1= public ip eth0= private ip so, I am following the below ...
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After iptables to nftables conversion, unable to connect to http nextcloud server and apt doesn't connect

I want to enable access to my nextcloud server and be able to use apt update. I used to be able to before my iptables to nftables conversion. However, after the conversion, its no longer possible. ...
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Access ASP.NET website deployed on IIS Windows Server from outside network

I have an ASP.NET website deployed on IIS in Windows Server. It works fine in LAN. All PC in the network can access the website using the IP of server and port. Now I want to be able to access the ...
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Can I use Laptop with one WiFi and one Ethernet Port interface to setup firewall - OPNSense?

I am trying to setup OPNsense Firewall at my residence using a spare laptop which has one WiFI and one Ethernet interface. I was able to install OPNsense and configure the interfaces to LAN and WAN. ...
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Route all traffic through a WireGuard Hub and Spoke VPS (Nftables)

As mentioned in the title, I am using a WireGuard Hub and Spoke configuration to connect my network at home to RoadWarrior peers. Unfortunately I have no public IPv4 and v6 address at home and on the ...
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Google Cloud Serverless VPC Access Not Working in Both Directions

I have a Cloud Run service which I would like to connect to my default VPC network through a Serverless VPC connector. The final goal with this is to allow my Cloud Run instances to access an on-prem ...
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How to correctly set limits ports?

So im currently working on setting a simpel server up with a game server using port 30110 and 30120, but i clearly getting dossed like crazy, how is the best way to protect against this, like i have ...
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VPS can not be reached in any way from some clients; IP routing issue?

I have been running a VPS which is situated in Amsterdam. It has not given any problems, and can be reached from most locations reliably. Except when a French customer was not able to reach the server ...
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With Ansible, should I limit SSH connections by IP?

I'm familiar with the standard Ansible best practices for secure connections (disabling root access for hosts and configuring key-based SSH authentication). Should I also use hosts.allow or iptables ...
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MSSQL Brute Force Attack, Error Code 4625 Audit Failure, Error Code 10016 DISTRIBUTEDCOM

We have a Windows 2012 Server from Godaddy accessible through remote desktop. Recently we started getting Error Code 4625 Audit Failure and Error Code 10016 DISTRIBUTEDCOM, these are happening almost ...
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Allow port forwarding through vpn iptables killswitch

I have a debian virtual machine thats connect to a openvpn server. Right now i have a kill switch working well on iptable, and the vpn connection works whithout any trouble. Let's share this ...
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Firewall use-case on a server with no open ports?

I know a firewall is a must on any machine connected to the Internet, no matter what. I was wondering though what would be a firewall use-case on a server with absolutely no open ports. For example, a ...
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Connect multiple azure resource groups via route-based vpn to same on-site firewall

We are developing an app in Azure, made dev/test/prod ressource groups and want to connect these via Site-to-Site VPN to our On-Prem environment. Connecting one of these ressource groups isn't a ...
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Blocking forwarded traffic with OpenWrt fw3 firewall

I can't find out how to create a fw3 rule which does what I want (block all traffic from 192.168.1.119). I have this in /etc/config/firewall config rule option ...
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Can send email with Postfix, but cannot receive emails

I am moving my email server from one server to another. I have tried everything, but can't get the email to receive any emails. I think I have found the problem. It is is the firewall. I am using ...
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Nginx not serving from port 80 and 443, but works on other ports

After rebooting my VPS, I noticed that all nginx hosts that were bound to ports 80 and 443 started returning ERR_CONNECTION_TIMED_OUT and no new entries were being outputted to access.log I simplified ...
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UFW on debian vps not working as expected

I have a Debian 11 VPS server with ufw installed and running with some rules working and others don't, I have tried resetting, disabling, reloading and even uninstalling but all in vain. Here is my ...
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Docker port publish host mode and iptables

I'm struggled with docker and iptables. Everything works fine except for containers with ‘host’ port publish mode. Ingress works fine. I have a rule to open nginx container 80 and 443 ports to world -...
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Firewall throughput and LAN Speed

A quick question, I'm considering to buy a firewall which offers throughput up to 450 Mbps and has fast Ethernet ports, my understanding is that the firewall limits the internet speed but not LAN ...
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Checkpoint & ASA visabilty

We are using both checkpoints fw and Ciscos ASA, I'm looking for a tool, preferably with web gui, to allow our developers see if the connection was dropped either in the ASA or in the checkpoint. One ...
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Iptables : restrict access to container

I'd like to restrict access to a docker container to only a few ip adresses. There are two interfaces on the server : the public (eth0) and the private (eth1 : 192.168.0.1). I only want the IPs on the ...
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Comodo WAF Internal Server Error

I have a Linux server, with the following specifications and in WHM when I want to Comodo WAF open in plugins , I get the following error in the address https://example.com:2087/cgi/addon_cwaf.cgi ...
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Firewall rule for IAP traffic added but ssh for GCP server still not working

I am running a .dev website on GCP. The website is running but whenever I try to access the vm via ssh, it returns "Connection via Cloud Identity-Aware Proxy Failed" Code 1006. I am not too ...
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How to alter firewall (iptables) log rules such that they stop flooding the primary console on AlmaLinux 8?

I have a constant deluge of firewall blocks showing up on my console in AlmaLinux 8: How do you modify iptables rules / settings so as to disable these from showing up on the primary console and to ...
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what is the use of "remote(client) port" for inbound firewall rule?

In firewall settings, local port for inbound rule is pretty obvious: that is the port you want to listen. However, remote port sounds nonsense: In typical protocol, client uses arbitrary port so ...
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Shorewall: IPSet from blrules not applying

We're hoping to make use of IPSet to manage temporary IP blocking from sources (CSF+LFD, fail2ban, wherever relevant). The purpose would be that routers using Shorewall at the edges would make use of ...
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Firewall not keeping relay attempts from reaching postfix

I have a centos-based vps managed with webmin and every once in a while I get a few hundred emails like this one: From: MAILER-DAEMON@mail.<redacted>.com To: postmaster@<redacted>.com ...
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How to stop rejection of DNS queries?

Although service dns is allowed through firewalld, DNS queries received through an internal interface are denied. Here is the network: PC ------------- SERVER ---------------- DNS Server > nslookup ...
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Checkmk behind NAT can't reach agent in dmz

I have checkmk running in our lan. I want to monitor a linux vm in the dmz. So i installed the agent on the linux vm, enabled ipv4 for it, but checkmk can not find any services since the agent was not ...
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Firewalld without interfaces on public zone

On my Oracle Cloud server, the public zone has no interfaces attached, neither does any of the other zones. But still if I allow a port in the public zone, it does allow the traffic through. So why is ...
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Does blocking all outgoing traffic on cloud instance lock me out?

I have to test an app which first downloads data, but then, can not communicate with the world for the duration of the test (so it doesn't gossip stuff). There are ways to enforce this on the app, but ...
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Cannot connect to a on-premise VM via Cloud VPN from Google Cloud Run

I am trying to reach an on-premise machine (let's call it exovie) from Google Cloud Run via the Serverless VPC Connector. Simplified network configuration This is how the network is configured: The ...
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How do i configure ssh to listen in port 22 but restrict use only if some kind of tunneling is provided?

So i have this ssh server, which is currently listening in some port lets say 5003(just for the sake of it) i can easily acess it with using the flag in unix and correctly putting the port. This would ...
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How to prevent being cut off a remote machine after a misconfiguration of a firewall playbook

Despite being careful, such a situation can happen and can be very toilsome to fix.
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Counts externally accessed IP addresses via iptables or something similar

I own a hosting company and I often face the situation where my clients using weak passwords end up being broken and at the same time my VPSs become the source of scans on other hosting companies. I ...
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Why we get TCP retransmissions through IPSec Site-by-Site Tunnel

We use two pfsense firewalls at two locations and have connected the locations using IPsec site-by-site. That had worked well for a long time, now we had installed the 2.6.0 update at both locations ...
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Firewalld port forwarding fails

I'm trying to replace an existing tunnel with firewall rules: firewall-cmd --zone=public --add-forward-port=port=9999:proto=tcp:toport=9999:toaddr=100.1.1.1 This should forward all incoming TCP ...
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IPs blocked automatically by my firewall are all from Cloudflare

I have a website that uses Cloudflare, in my host level firewall I have noticed that all IPs automatically detected as malicious are identified as "owned by Cloudflare" and I don't know how ...
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lastb shows an IP address that is firewalled

I normally never get any bad login SSH attempts, since my port 22 is deeply burried behind a firewall that blocks all but one IP - my VPN. Yet, I just ran -lastb and to my jaw-dropping surprise it ...
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How to block internet access for OpenVPN clients and restrict traffic to VPN network? (Installed with openvpn-install)

I setup an OpenVPN server using openvpn-install. I would like clients to be able to connect to the VPN server, but any traffic aimed towards the internet instead of the VPNs local network should be ...
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Create an NFQUEUE rule to match a local addresses destination in my raspberry pi router

I'm working on a project to verify the source of each packet if its destination is one of several IPs on the LAN network. I'm interested in the LAN IPs, not the WAN. I tried to create many matches ...
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Firewall - nftables blocks outbound traffic

I've got a VM at a hosting service and installed a basic firewall with nftables. However, when it is active, all outbound traffic seems to get blocked. For example, when trying to ping google.com, I ...
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