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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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How to interpret Firewall logs?

Today I have found few failed auth attempts on ssh server and I decided to check all logs for suspicious activity. Here are my router firewall logs (small part of it): Dec 12 21:24:12 kernel: DROP IN=...
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1answer
12 views

How to open a port on a Google Cloud Compute Engine

I have a Windows Server 2008 R2 instance, I want port 3000 to be accessible to the outside world. Here's what I have done so far. I have configured that at the VPC network/Firewall Rules section. But ...
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8 views

Mikrotik routeros maximum number of filter rules

We need to deploy a service using Mikrotik routerboard CCR. We need to know how many filter/mangle rules a Mikrotik device can support: hundreds, thousands ? What about performance, cpu and memory ...
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2answers
28 views

Single iptable rule matching /32 and jump

We need to install a single iptables rule that match every source /32 user ip and jump to 'user chain': iptables -A INPUT -s "EVERY_USER-IP/32" -j "USER_IP/32_CHAIN" because we have hundreds of ...
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2answers
35 views

Setting up firewall using iptables

So, its getting more serious. I set up a "real" server. Before that I already configured firewalls using VMs. Now I got a question about which IP I need to allow, as I want to reject connections by ...
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25 views

SSL connection error but works if you telnet port first

I'm troubleshooting a connection to an application (Citrix Netscaler), between several countries in a complex network. There are definitely firewalls along the route. Machine is pingable tracert is ...
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0answers
7 views

Firewall IP whitelist vs IPSEC VPN (Azure specific)

We are about to move our company's internal web app and samba shares from a datacenter to Azure. All our locations have a VPN connection to that data center. Instead of creating all new connections ...
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19 views

Iptables block doesn't work [duplicate]

Someone doing DOS attack on our server. "UDP (60 bytes) from 207.180.196.234:60797 to x.x.x.x:9987 on eth0 " Targeting 9987 port ( Our TeamSpeak3 server port ) We are trying everything what we can ...
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27 views

NAT timeout how to switch access

The SS server of 127.0.0.1:1080 is also enabled on the NAT server. iptables -t nat -A POSTROUTING -s 10.0.0.0/24 -j MASQUERADE I want him to automatically add REDIRECT --to-port 1080 when it times ...
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0answers
49 views

How to find out what is blocking a port in Centos 7?

I'm trying to make a mailserver with postfix/dovecot but I'm stuck. The problem is I cannot connect to some of the ports I want open, for example 587. As far as I can tell the port is open and ...
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1answer
39 views

Should a private virtual LAN be filtered

I'm a dev trying to learn others things and my current objective is to create a "virtual" lan on an ESXi host. I've created a VM which work as the LAN gateway to the WAN and some VM that are ...
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20 views

Check for filtered ports from the same machine in Windows

I have two cases: Case 1: I run a service which opens port 8000 and I do netstat. I find 8000 as "LISTENING". Now I block it using windows firewall. I do netstat again. It is obviously going to show ...
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28 views

Can I tell if network traffic captured by the firewall was solicited or not?

From a Fortinet firewall event log, can I tell if the traffic was solicited or not? I mean if the traffic was a reply, or a new connection.
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2answers
42 views

pfSense allow ping only from 1 IP address

We are a dutch company with an office in the USA. This office has an pfSense firewall device with the 182.12.12.12 IP address . In the Netherlands' office we have an IP address like this: 100.12.10....
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1answer
21 views

how to allow some specific user/machine connect to a block port on production server via public internet?

(I don't know if I am using the right tool for the job, but just try) My purpose: Block access from internet on postgresql database port 5432 on production server. But allow some user/local machine ...
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0answers
14 views

Linux Firewall on Webmin failed to load

I'm going around in circles here... So yesterday everything was fine in Webmin 1.580. But it was nagging me about not being the latest version, so i update to 1.890... big mistake! I navigate to the ...
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0answers
5 views

port 80 closed after port forward and firewall settings [migrated]

Currently I'm having an issue that only somehow started to appear within the last day or so and nothing about my network setup changed that would cause these issues. I'm running a development ...
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0answers
20 views

Filtering HTTP methods such as POST, GET and etc in Kerio Control 9.x

I need to filter a couple of HTTP methods for specific URLs in Kerio Control. For example, I need to filter POST, PUT, PATCH and DEL methods but allow GET method for *.example.com. I look into Kerio ...
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0answers
13 views

Changing PF rules on the fly to mitigate damage of DDoS (OpenBSD 6.4) [closed]

This is a two part question, really. Keep in mind that I am a developer not a system admin, but being the only employee in the company, I wear ALL the hats. I have deployed my server with two ...
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0answers
14 views

Source NAT on Juniper SRX300

I'm having issues setting up the Source NAT on my SRX300 firewall. The firewall is connected to an LC-panel through a fibre optic cable in port 0/6. I have set the public ip on that interface and have ...
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1answer
32 views

How to disable internet but remain connected to LAN network?

I have a windows computer that I want to isolate from the internet. I need this computer to remain in contact with other devices on the network and be able to VNC into it. I saw some solutions saying ...
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2answers
80 views

Why do I need an external address to make an internal connection between GCE instances?

I have a VPC (10.11.0.0/20) with 3 VMs. VM2 and VM3 are the same except that VM2 has an external IP address (ephemeral) and VM3 does not. They're both running a Docker image with a web server exposing ...
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1answer
36 views

Port 80 mixed up among clients using DNAT

I'm trying to set up a network like this: ...but I'm facing an issue. Here's the point: If I try to reach (e.g.) mywebsite1.com from external it works like a charm and it's shown my wonderful ...
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1answer
24 views

Block only port from being accessed outside except localhost

On Centos 6 machine, how can I block port 8888 from being accessed except by localhost/127.0.0.1 only using iptables? Actually, I have another port that I want to listen on 8000 instead of 8888. ...
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14 views

Whitelist outgoing SMTP server using CSF

Am trying to setup Mandrill for transactional emails for one of my web application. I decided to use the SMTP method(credentials from Mandrill) than using API as it would be easy for me. In my VPS ...
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1answer
25 views

IPsec: Can ping hosts of other network with the firewall but not with hosts behind the firewall

I have a endian firewall and a established IPsec tunnel. The firewall is in the network 192.168.100.0/24 and has the address 192.168.100.1. The hosts that I try to ping are in the network 10.4.0.0/32 ...
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2 different ways to express blocking traffic in Windows Firewall?

In Windows Firewall Advanced Settings, what is the difference between enabling a process and then blocking it which result being a green check, and blocking something and enabling it which results in ...
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1answer
42 views

Can't connect to ipsec server running in docker behind firewall

I have a setup which I dont think is very difficult but cant get it to work. Working setup: An ipsec server running in a docker connected directly to internet. The clients can connect. Not ...
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1answer
30 views

Restrict traffic between peered VNETs in Azure

I'm working with Azure, and I have 2 VNETs, each in its own resource group Peering + | ...
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1answer
46 views

Enable communication between Azure virtual networks

I have an Azure subscription with 2 different resource groups, Test and Prod. Each resource group has a VNET with a bunch of VMs in it. There is a VM in Prod that acts as a license server, and ...
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1answer
46 views

Having issues opening up a port for my instance on GCE

I'm running a GCE instance. I ran sudo ufw allow http && nc -l 80 and it succeeds, showing that 80 is open. However, when I try to open up a server by running waitress, a Python server, with ...
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0answers
60 views

Can't connect to mysql on remote server

I have several machines running CentOS, one of which is set up as the mysql server. I had been running this for a while, and was able to connect to mysql from the remote machines with no problem, but ...
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1answer
41 views

Can one device simultaneously be a reverse proxy, load balancer, and firewall?

From my understanding you have: Reverse Proxy: A device standing between internal servers and the internet. Some goals: SSL termination, caching, obfuscation, more freedom to change internal ...
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1answer
51 views

Debian 9 firewall is blocking git@bitbucket.org

I'm trying to use git push or ssh -Tv git@bitbucket.org but the server is blocking the connection. I don't have ufw of iptables istalled... so what is blocking the connection... is there any log? can ...
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0answers
19 views

How do I config Comodo Firewall to allow file sharing a specific server

I have COMODO Firewall on my laptop and want to access shared files on a local network. But the firewall restricts access to these resources and I have to disable my firewall to access shared files. I ...
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0answers
36 views

iptables block all traffic from a IP after TCP handshake completed

Other than writing a script that monitors the log file to see if a full TCP connection has been created to a certain port is it possible to create a rule using the recent table that will block all ...
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3answers
425 views

How to confirm a low number port (67 UDP) is being blocked by my firewall?

Based on this answer, blocking port 67 UDP outgoing should be firewall-cmd --permanent --direct --add-rule ipv4 filter OUTPUT 0 -p udp -m udp --dport=67 -j ACCEPT firewall-cmd --permanent --direct --...
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2answers
21 views

What should be the behavior after also dropping outgoing destination-unreachable packets?

On system A I'm using ip6tables and I'm DROPing INPUT packets coming from system B through IPv6. As expected, when system B uses ping6 to system A, it sees destination unreachable. However, when on ...
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0answers
20 views

Connect to OpenVPN from subnet, PfSense

I'm trying to setup OpenVPN on PfSense so all network client traffic is tunneled through a VPN by default. The OpenVPN service connects to the provider's servers just fine, but the clients cannot ...
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0answers
90 views

Running Wireguard disables SSH access to the machine

I have a machine C which I can SSH into from my machine B. But when C uses Wireguard to connect to the internet through machine A, I no longer can SSH into it from B. What do I do?
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1answer
42 views

DROP packets (instead of REJECT) from specific port when no application is listening?

I'm using Ubuntu 18.04 with iptables. I want that attackers would see a consistent state when trying to map my ports. I want all my ports to appear as filtered (i.e., drop everything). However, some ...
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1answer
106 views

Seperate network connection on server with 2 NICs

This is the setup we are aiming for in the picture. As you can see, the supervisor server (CentOS 7.5) has two physical nics (eth0, eth1). One of the design goals would be, to have eth0 allowed to ...
0
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1answer
18 views

Outbound routing on Azure VM

I have a test VM in Azure, private IP 10.0.0.4 running an IIS site. I have a Watchguard firewall VM in Azure with two interfaces, one has a public IP and a private IP of 10.0.1.2. The other ...
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1answer
34 views

Firewall block all but one ip spoofing

We have a server which accepts traffic coming from a few sources (ip addresses) and accept's it (using firewalld). All other traffic inbound is blocked. How likely is the risk that somebody ...
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1answer
42 views

Can firewall rules be applied to internal GCLB?

tl;dr We're experiencing issues with services behind internal Google Cloud Load Balancer not being able to reply when response is over a certain size. Upon some tcpdump'ing and wireshark'ing, it ...
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1answer
49 views

Two similar services, two IPs, one server?

I'm running a CentOS 7 box. On this box I have two services which should both be exposed using port 443 for HTTPS traffic. Using a reverse proxy is no option, one service cannot be reconfigured to ...
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0answers
49 views

How to setup an Azure Firewall in a hub-spoke model to forward to the correct spoke subnets?

I have an Azure environment with different VNETs for each environment (dev, test, and so on). Each VNET has its own Azure Application Gateway with WAF enabled (due to the limitation on number of sites/...
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1answer
72 views

GCP Firewall - Deny by User Agent

Is it possible to block user agents in the Google Cloud Platform Firewall? I have a specific one I require to block. However as I offload SSL to the Load Balancer it is that which makes the request ...
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0answers
42 views

GeoIP blocking and fail2ban

Both involve adding firewall rules, is it worth implementing fail2ban as well as GeoIP blocking on the same system? Has anyone done this? Is fail2ban left with anything left to do or is it not worth ...
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0answers
17 views

Cyberoam Installation - Cannot Reach server Error

I have downloaded the Cyberoam tar file and have extracted it using tar command in the location /home/ec2-user which created a directory "CyberoamLinuxClient"inside which there were two files "...