Questions tagged [firewalls]

Concerned with software or hardware firewalls

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2answers
1k views

Configure Linux to allow network activity based on binary?

On Windows, rules can be added to the firewall to allow/deny network traffic based on which binary is sending/receiving the data. Can this be done on a Linux box, and if not, why not? Is it a bad ...
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1answer
2k views

How SSH Deep Inspection works?

I just saw an option in Fortinet NGFW regarding, SSH Deep Inspection. So my question is how Deep inspection or whatever can inspect or find any malicious activity on encrypted packets?
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If nmap reports a port is open, does that ALSO mean a service is listening on the port?

I have a Thompson TG585v7 router/firewall whose firewall is configured to FORWARD several ports to a computer X54 within the LAN. These ports are in the range 1024 through to 2500 That X54 ...
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5answers
16k views

Firewall rules by URL

is there a solution to create FW rules by URL instead of IP for inbound traffic? For example a.example.com and b.example.com are the same IP on the DNS, but they are different sites, is there a ...
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2answers
8k views

Benefits of REJECT over DROP on a single PC

Recently I learned about the difference between DROP and REJECT in a firewall. I understand that REJECT is better because it closes the connection immediately instead of waiting for timeout as DROP ...
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2answers
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Why does a nmap scan give different results depending on whether it's run from inside or outside a LAN

I am testing/setting up a Thompson TG585v7 router/firewall. Results when running nmap from a computer INSIDE the LAN $ sudo nmap -O 210.86.xxx.xxx Starting Nmap 6.40 ( http://nmap.org ) at 2015-...
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3answers
1k views

Is there any method to prevent/trace DDoS attack?

I have a Debian Linux server which runs a few online game services. I have some competitors in this area and I think one of them is behind the DDoS attacks. I have full access to the router, so I set ...
4
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1answer
706 views

Blacklisting during a penetration test?

So i had a debate recently where one of my colleagues believed that by launching a penetration test (one requested by our clients) from our one of our IP's we could potentially get that IP/all IP's in ...
4
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1answer
517 views

How did my homepage get changed in IE?

I have rarely used IE in the past. I just use it to test how a website looks. Today all of a sudden when I went on to open IE, it opened with a homepage that wasn't set by me. It was an address of a ...
4
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1answer
9k views

Fail2Ban does not ban failed root login attempt

I have a small server which only open ports are ssh, http and https. I have fail2ban installed and set up so that after 3 failed attempts someone gets blocked for 10 minutes (thats the dafault I think)...
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2answers
739 views

Firewall design for big enterprise business

I am wondering if there is any best practice firewalling rules that should be put in effect in most modern networks. For example should the network atleast have the following firewall zones? Client ...
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3answers
229 views

Should network firewall rules be secret?

At my workplace only the security team have access to see the rules on the server network firewalls. Developers and system engineers don't have any visibility, so they just deploy applications to ...
4
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1answer
153 views

Using a bastion server: how to model an emergency entrance?

I have set up a bastion server (A) that acts as the only "hallway" to enter a bunch of other private VPS's (B). That is to say: the private machines only accept SSH-connections from (A) on a non-...
4
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2answers
5k views

Is there a difference in security between an IP address white list and a domain white list with TLS?

It seems to me that an IP address white list relies on easily spoofed information, while a domain white list, if it forces TLS, at least, relies on the validity of the certificate systems. I may be ...
4
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1answer
440 views

IPsec: Is AH in tunnel mode secure?

I have a site-to-site IPsec VPN which was performing poorly (10 -20% upload/download speeds as a percentage of available WAN circuit bandwidth) when using ESP in tunnel mode with DES encryption and ...
4
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1answer
513 views

Exploited by newbie3viLc063s

My debian server got exploited by some scriptiekiddie who used Newbie3viLc063 http://pastebin.com/jma8JRG1 . Scriptkiddie uploaded logo_php.png to my server (My permissions sucked :s) and he did run ...
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2answers
4k views

IPTables DDoS protection working with per client IP address counter AND UDP

I am looking to protect LAMP server with a software, which will detect above average number of requests from single IP numbers (in this case DNS queries), and add these hosts to IPTables deny chain. ...
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3answers
16k views

How do you properly setup Tor on Windows 7?

How do you properly setup Tor on a Windows 7 box to guarantee that ALL connections will run through Tor?
4
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1answer
434 views

Placing a firewall—without creating a new subnetwork

I have a couple of networks that have multiple IP addresses, and where I have absolutely no choice as to the equipment used for the network's edge router (the device that connects both to the LAN and ...
4
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2answers
9k views

Is it dangerous to disable the IPv6 firewall built into many home routers?

The router that my ISP has delivered contains an IPv6 firewall. The only configuration option is whether it is on or off. Apparently, this firewall simply denies all incoming connections. I ...
4
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1answer
574 views

How to distinguish between “normal internet” Port scan and more “serious” port scan preparing attack?

In a complete network infrastructure, with firewalls, routers, servers supervised by a SIEM, LogPoint here. Of course, there is a private network and public servers. in the LogPoint there is an ...
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1answer
1k views

Modifying shell code to bypass Windows Firewall

As part of my OSCP's training, I'm supposed to get a shell on a Win7 machine using browser's exploit (MS12-037) with Windows firewall on. I have an idea but I'm having hard time applying it. What I'...
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2answers
110 views

monitor port scan on the same segment

if theres a port scan on the same segment and it does not reach the firewall at all, it is not detectable by anything. is there any solution to that ? maybe using the windows fw on ach workstation to ...
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3answers
3k views

Effectively limiting outgoing firewall traffic to frequently-changing IPs

PCI DSS 1.2.1 states: Restrict inbound and outbound traffic to that which is necessary for the cardholder data environment. Verify that all other inbound and outbound traffic is ...
4
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2answers
382 views

What criteria do you use for evaluating Client-Side / Endpoint security products?

What features are important to you in client-side AV and Firewall products? Who benefits from these features? Managment, the end user, helpdesk. Are there features that are being 'sold' by the ...
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1answer
406 views

Firewalling: Screened Host / Bastion Host

I'm having troubles understanding the definition or the idea behind screened host / bastion host that you often find in the internet or books: Is the bastion host in this context, the firewall itself?...
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1answer
5k views

Question about IPv6, NAT, firewall, port forwarding, upnp and security

In the next months/years my ISP might give me IPv6 for my home connection. But what are the security implications? Will local network servers/embedded devices be accessible from the whole internet? ...
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2answers
5k views

What is more risky? Database Server in DMZ or Trusted Network?

Hoping this is not a dupe of any of the related database / DMZ questions, but I don't think any of them answered my question sufficiently. Assume the following A web server is being used for ...
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3answers
4k views

IP Spoofing a threat?

We have an internal intranet system which is only accessible from a few internal VLANs. Our main external firewall blocks all access to the internal webserver – or rather, has no rules to allow access!...
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1answer
3k views

The Shadow Server Foundation constantly trying to get access to mDNSResponder

Update September 2018: The events described below still happen to this day though less often from servers of The Shadow Server Foundation. By now I have denied access to most of their IP addresses, ...
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2answers
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how can an attacker access a system through a compromised router?

Let's say an attacker gained access to the admin panel of a home router with port 21, 23 and 80 open. I mean the attacker has full control over the router, thus being able to port forward, etc... ...
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1answer
4k views

Is it possible to force client use TCP instead UDP for DNS queries?

Assume I am managing a firewall between DNS server and clients. Is there any way to force clients use TCP rather than UDP, so we can prevent DNS spoof types of DDoS attacks?
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3answers
706 views

Segregating a Printer in my Enterprise Network

I have a EAP-TLS network at home which I've managed for some time now. I just got a new Brother HL-5470 printer so I can finally print things at home, which is really nice. The only problem is that ...
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2answers
1k views

Long character sequence in first string of HTTP GET request breaks the web service's HTTP response. Buffer overflow?

During my current security audit test I've stumbled on something I can't possibly comprehend. The behavior exhibits signs of a buffer overflow in the target or in some intermidiate service (HTTP proxy/...
4
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1answer
316 views

DMZ Firewall settings

I am involved in project where I have to install a new server for a new application to a preexisting production network. The new server shall sit in the DMZ and two controllers will sit on the ...
4
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1answer
2k views

Isolate a Virtualbox VM from local network [closed]

I have the need to isolate a virtual machine created with Virtualbox from the local network but I need to provide internet access to that machine. It is the first time that I face this kind of problem,...
4
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1answer
574 views

Why strip accept-encoding?

It seems that there are multiple "security" products which strip or mangle 'Accept-encoding' headers, thus forcing non-compressed responses from HTTP servers. I've been trying to imagine if there's ...
4
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1answer
1k views

IP address filtering vs web application security

We have a web application behind a firewall that requires no user authentication. If we open up access to this application via the firewall to a small list of IP addresses what is the risk of ...
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2answers
2k views

Firewall UDP Packet Source Port 53 Ruleset Bypass

I have a question regarding recent PCI DSS scan performed on our network. On some of the Windows 2008 servers (physical and VM), there is a risk found "Firewall UDP Packet Source Port 53 Ruleset ...
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2answers
133 views

Is there such thing as an OS “internal firewall”

I was wondering if there is such thing as an OS "internal firewall". If it exists, it must be under a different name. I am looking for a way to control which applications can talk to which other ...
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2answers
2k views

Benefits of home router behind Linux firewall?

Like a lot of people I have a simple consumer grade router at home. The setup is pretty standard: Ethernet from the cable modem --> router's WAN Given the poor track record of consumer routers ...
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2answers
389 views

How common is port-knocking? [closed]

Today I read about port-knocking for the first time. It has been a pretty known concept for more than ten years, but I don't know anybody who uses it for their servers. How common is the usage of ...
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4answers
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Find out what Linux software is trying to phone home

I have seen some suspicious outbound communications blocked on my VPS, which hosts a small experimental Web site, and want to find out which application is making the attempt. The server is running ...
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2answers
5k views

Blocking incoming traffic from privileged port (< 1024) to mitigate DNS DDos Amplification attacks

Hope someone can clarify. As I understand, in a DNS DDos Amplification attacks Multiple DNS queries are sent to a vulnerable name server with the source IP spoofed to that of the target server. The ...
4
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1answer
231 views

firewall with cloud based malware analysis risks

Palo Alto, and probably others firewalls will offer it, has a feature to do malware analysis in a separate (cloud-based) process that does not impact stream processing. What I would like which risks ...
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0answers
333 views

Is there a CMDB with a workflow engine out there for managing firewall rules? [closed]

I've spent some time trying to find something like a CMDB with a workflow engine for firewall rule requests and couldn't find anything. We've just started using RedSeal at work and we've came to the ...
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1answer
2k views

I want to restrict access to Nextcloud using OpenVPN

Is it a good idea to restrict access to my Nextcloud server by using OpenVPN, so every user (this is for small group of people), will get their own VPN account and after that they will be able to ...
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6answers
6k views

How do I prevent data from leaving my network?

I have a network of about 10 computers and I want to prevent sensitive data and source code leaks. To achieve that, I would like to block all file uploading / attaching. What are the options ...
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3answers
18k views

What, specifically, does the Windows Firewall do?

My understanding of the situation is that, when the Windows firewall is off, every port on the computer (all 65535 of them) is fully open. This means that any application running on the computer can ...
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2answers
3k views

How does a firewall help to protect a server?

Since a potential attacker will exploit the services that are already open to public by firewall rules, how will a firewall help to protect my server from attackers?