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Questions tagged [firewall]

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

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AlmaLinux blocking outgoing connections

I have a new AlmaLinux installation that is blocking outgoing connections to most ports, with the exception of a handful. I notice this mostly because the server runs Exim and no e-mail can be sent on ...
David Mora's user avatar
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“Difficulty Accessing Redesigned Website from Local Network - How to Resolve 404 Error

Description: I recently redesigned our website and migrated it from Namecheap hosting to Hostinger. While the updated design is accessible from external networks when hosted on Namecheap, I’m ...
aiham nimer 's user avatar
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Firewalld: adding a source IP blocks SSH. Different behaviour between versions?

I have two servers with different versions of RHEL and firewalld. Both are configured the same, but they are behaving differently when I add a source IP to a zone. Server A: # cat /etc/redhat-release ...
Darren's user avatar
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How to block Web3 Domains

There are some domains called "decentralized" (Web3), promoted by Unstoppable Domains and Ethereum Name Service, example: .888 .anime .bitcoin .blockchain .coin .crypto .dao .eth Is there ...
acgbox's user avatar
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ExtremeCloud IQ schedule a task

Is it possible to make a task to schedule a automatic update to all APs every ones in the 3 months? And reboot at night 3 aclock?enter image description here
TraineeNetEngin's user avatar
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UFW -- Will placing a specific IP above a CIDR allow that IP superseding the CIDR deny?

I cannot reliably get results from my testing .. But if I had said rules in this order: zak@Web:~$sudo ufw status Status: active To Action From -- ...
Zak's user avatar
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Better way to block IP Addresses with an Azure VM

I am using Azure for my virtual machines and it gives you a way to block IP addresses in the Network Security Group. However this IP list is getting quite long. Is there a better option to do than ...
Mike Flynn's user avatar
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Wireguard and Ubuntu 22.04. Forcing traffic from port 25 over VPN

So Im hosting a server in a docker container which is a client in a VPN network. I Cant send any egress traffic out of port (say ummm 52) through the host. That box is a client to a wireguard server. ...
Nimrod5000's user avatar
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FortiGate and WireGuard UDP hole punching

I am working on a project that uses WireGuard and UDP Hole Punching to create a mesh network between peers. The peers are mostly behind residential home gateways where the hole-punched tunnels work ...
PrecisionPete's user avatar
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how to reset asmb8-ikvm firewall

Due to a misconfiguration of the firewall, I am currently unable to access the IPMI of the local server(Asus p10s-i). When executing ipmicfg -fd 2, I receive the error message "command not ...
ATOM's user avatar
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Wireguard clients can not KDE connect between peers

I succesfully established a Wireguard VPN from a Rocky Linux 9 server at the cloud. As of now there are two clients: a Fedora desktop and an Android mobile phone. The first problem I want to solve is ...
Clodoaldo's user avatar
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How to disable Network Interface for SSH?

In my linux machine, I have 10 network interfaces available like eth0, eth0.67, eth0.70, eth0.97 etc,. When i run the command nc 160.48.249.170 22 to check, i get like below: root@icon:~# nc 160.48....
Karma Yogi's user avatar
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How to put multiple VMs behind a single *private* IP address on Azure?

I'm working on creating a Blue/Green deployment for a product in Azure but I'm running into a problem regarding outbound traffic to an on-premisses database. Our initial idea can be seen in this ...
Leonardo Tavares's user avatar
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fail2ban iptables REJECT rules not working [duplicate]

I managed to setup fail2ban and monitor my mysql database logs because I am being brute force attacked through my database login. the database is in a docker container and fail2ban is on the host ...
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Screened subnet implementation and nat

I'm trying to implement a screened subnet but I don't know which is the right way to do it. Is it correct to have both internal and external routers doing NAT (IP Masquerading), while internal one ...
Alfatau's user avatar
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How do i stop packet flooding on my server? [duplicate]

I use a debian server to host my site, but i've found about this vulnerability in it that it could receive half the packets in a packet flood with this command, ping -s <size of packet in bytes> ...
mohammed's user avatar
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Outbound IPv6 connection replies not routed back to firewall in VPC

In a newly-built AWS VPC (deployed with Terraform to minimise typos), I have one "DMZ" subnet and one internal. A firewall appliance bridges the two, with an interface in each. Both ...
Ian Gibbs's user avatar
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How to catch process being blocked by outbound iptables fw? [duplicate]

NOTE: Thanks for suggesting answers. I'd dispute this is actually a duplicate, but hey. The main issue (as stated below) which the suggested answers don't seem to address is that outbound iptables ...
TommyPeanuts's user avatar
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Connection to host reset when accessed via VPN or behind corporate firewalls

A client of mine was reporting connectivity issues from a lot of his customers who are either accessing his website from behind a corporate firewall or via VPN recently. I did check the endpoint it ...
user1192748's user avatar
1 vote
1 answer
139 views

Bypass nftables drop rule

tldr; bridge (see below) doesn't work if there is a matching drop in another table (like the default rules of firewalld). Hello, I'm building my own VM lib (kind of quickemu). I have a problem with ...
ange's user avatar
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Suspicious process running under user postfix

I have a VPS on which I have installed ConfigServer Firewall for about a year now. This morning I started to receive this kind of emails from CFS. I've checked mail.log and auth.log and everything ...
srmnpt's user avatar
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1 vote
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network unreachable for gcloud compute engine instance

I've just configured my first google cloud server with an ipv6 address. When I try to run wget to the address it fails: wget -6 https://[2600:1900:4180:bfa7:0:0:0:0] --2024-03-04 18:20:39-- https://[...
Brett Sutton's user avatar
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OpenVPN Allow clients to acess more machines

Currently, my OpenVPN Windows Server (192.168.15.56) only allows connection to itself and Firewall is disabled entirely for now. In my ISP Router I have a rule that allows remote connections for all ...
OCEANBLUE's user avatar
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Redirect all HTTP/HTTPS traffic through WireGuard to external HTTP Proxy

I have set up a Wireguard VPN whereby all of my devices connect to a Wireguard peer running on a computer with a public IP address (host). My Wireguard is set up so that clients connect to the host on ...
TopCat's user avatar
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IP6tables does not apply ACCEPT rules

My server is an IPv6 only server, I'm trying to write firewall rules using ip6tables and it looks something like this Chain INPUT (policy ACCEPT) num target prot opt source ...
Bad_Panda's user avatar
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2 votes
1 answer
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How to set iptables to block incoming requests to the server but still have internet connectivity

I have multiple services that are running on my server. But I do not want them to be exposed to internet. My input chain rules look something like this -P INPUT ACCEPT -P FORWARD DROP -P OUTPUT ACCEPT ...
Bad_Panda's user avatar
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Debian Firewall will not forward traffic from interface x to tun0

I want to have a debian system working as a router with openvpn traffic, where all traffic on interface x should be forwarded to openvpn interface y. Following pic shows my network setup, more or less ...
kasper2083's user avatar
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Cannot reach DNS server on vm (guest) through Sophos XG 310

I have a vm running Windows Server 2k19 hosted on ESXi that basically acts as a DC for authentication (AD). The host is connected to a pSwitch (Dell s4128f-on) that is in turn connected to my Sophos ...
Arthur Imona's user avatar
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155 views

Digital Ocean Firewall Prevent VPN Client Connectivity

Info: I have the below setup, connecting my digital ocean environment to my local network. Using strongswan on the Network A gateway I've made a site to site VPN connection with my meraki on Network B....
Matt Campbell's user avatar
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SSL / TLS Errors on only some wifi networks

I am having problems with the SSL handshake not completing when I am on some public wifi networks. This is a problem when accessing all of the endpoints for my app, and so from some of those networks, ...
Donovan Smith's user avatar
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NAT between 2 LAN interfaces in Opnsense?

I'm not a network pro so some of my terminology may be off. I've tried to explain what I'm trying to achieve in different ways to hopefully make my request more understandable. I have Opnsense running ...
user23401941's user avatar
1 vote
1 answer
80 views

Change Cisco Management VLAN

I currently have the following configuration. A Checkpoint firewall (which is the router) and 12 Cisco 9200 switches. SW1 is connected to the firewall. I need to change the MGMT VLAN from VLAN20 to ...
Daniel D.'s user avatar
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1 answer
191 views

Can't stop attack on nginx server

I'm currently struggling with my Digitalocean droplet (Ubuntu 22.10) which is under some sort of attack (maybe DDOS). The server hosts a containerized application that runs on nginx. Every time I ...
Gianmarco Santi's user avatar
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1 answer
99 views

One computer cannot access port from another on the same same network

I have two servers with relatively fresh installs of CentOS 9 Stream on the same network. I can ping and ssh between them so can prove basic connectivity. serverA AFAIK has port 1883 (mqtt) open and ...
Geordie's user avatar
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2 answers
138 views

Is it safe to expose monitd http server to the world

I'd like to use monitd for monitoring my webserver. I read it has built in http server. By default it is set to run on 2812 port. Is safe to open the port on firewall and view it via a browser?
Łukasz Korona's user avatar
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1 answer
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I keep receiving login attempt to my server until it gets down

I have a Centos7 server and after years of correctly working, yesterday it started to being unreachable (The server apps I have there were not rechable, the SSH connection gave timeout, etc but the ...
Faabass's user avatar
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1 answer
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How to SSH to different Virtual Machines attached to same Azure Firewall using same port?

We have host-Windows, proxy-Linux(same VNET, different subnets) and sftp-Linux(different VNET and subnet) machines in which SSH is enabled in port 815(SSH is done to domain set to each machines). Now ...
reshma m nair's user avatar
2 votes
2 answers
490 views

nftables rules can't ping to other server

So I have a quick and dirty firewall that I plan to use on my vps using nftables. Here's the initial rule table inet filter { chain input { type filter hook input priority 0; # ...
mhd's user avatar
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First SSH connection reset by peer, subsequent ones work

I am facing a fairly odd issue on a new VPS: Whenever I initiate an SSH connection to the server for the first time in a while, I get this: ➜ ~ ssh server kex_exchange_identification: read: ...
Klaus's user avatar
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2 answers
496 views

firewalld config for OpenVPN

I am trying to setup an OpenVPN server on a VPS running Fedora Server 35. I got the VPN setup and working, but am running into issues with the firewall setup. This is my first experience administering ...
Skenja's user avatar
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0 answers
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Linux iptables/UFW - Exclude ONE host from nat

Currently I am using UFW to NAT two IPv4 Subnets to VPN Interfaces like this: extract of /etc/ufw/before.rules: # NAT table rules *nat :POSTROUTING ACCEPT [0:0] -A POSTROUTING -s 192.168.1.0/24 -o ...
user3528657's user avatar
-2 votes
2 answers
89 views

Ip routing two subnets

I've got two subnets A: 192.168.2.0/24. Within A we have got a firewall and a connection to the internet. B: 172.16.12.0/24. They are connected with each other via a switch and both subnets are ...
Nils's user avatar
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Azure SQL Datasync IP address

We have to sync 2 SQL servers located in different clouds under the different tenants. One in Azure global cloud and another one is in Azure China. I've created a sync group in global cloud, added ...
Vyacheslav Benedichuk's user avatar
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131 views

LTE Mikrotik NAT not works

I've and LTE Mikrotik HRBwAPGR-5HacD2HnD and QNAP NAS server. My need was to route trafic to QNAP server (192.168.88.102) from internet(using DDNS and so on) but not able to perform it, maybe I'm ...
Victor  EStalin's user avatar
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1 answer
612 views

nftables fails on boot with "Error: Could not process rule: No such file or directory chain ingress" but same nft conf works with manual nft start

Over one year I have had a working nft configuration. After updating NVM of my network cards and "apt update & upgrade" I encounter the following error on boot. But nftables starts ...
cygent's user avatar
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-1 votes
2 answers
547 views

pfSense in disable all packet filtering mode allows web admin on WAN IP [closed]

A while back, I had a fiber internet connection installed at my business with a number of public IPv4 addresses. The ISP provided two blocks of IP addresses: a "P2P" block which contains a ...
cmshowers's user avatar
-1 votes
1 answer
86 views

Locked server because of IP spoofing

I have hetzner server. Inside this server there is Docker service which inside creates a few containers. Inside this containers I create vpn connections with openvpn. After connection I make some ...
Max Frai's user avatar
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1 answer
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Using two asymmetric uplinks

My current network topology is: Fact Firewall (I tested with OPNsense and IPFire, but I'm open to further suggestions) and the whole "ORANGE/DMZ" stuff are actually VMs/containers in a ...
ZioByte's user avatar
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1 answer
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Can iptables state miss some packets?

I tried to setup the iptable rules for MTA. As this MTA is meant only for receiving the emails I allowed INPUT packets from any to destination port 25 with state either new or established, and allowed ...
Ayush Gupta's user avatar
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183 views

Connection refused for http requests intermittently on multiple certain networks but not others, OPNSense Firewall, maximum confusion

I have been using an OPNSense firewall at my business for about a year now and its worked great. We use it to host some websites, an email server, and wireguard for remote connections. All on a ...
Tjk's user avatar
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