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Questions tagged [firewalls]

Concerned with software or hardware firewalls

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1
vote
1answer
322 views

Does blocking all ports make a machine more secure?

I have a machine that I use only to browse the Internet. What if I blocked all ports on this machine (inbound and outbound) except for port 80 and port 443, and restricted these two ports to an ...
0
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0answers
21 views

SSH link terminates every 20 seconds [migrated]

I am using a 3rd party software to get an SSH link into my device (remot3.it). I use Putty to SSH. All my other devices work but one device frequently loses SSH connection within 20 seconds but always ...
4
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2answers
118 views

How does a CDN actually prevent DDoS attacks, when an origin server accepts direct connections?

I am trying to understand how a CDN (like Cloudflare e.g) does protect against a DDoS attack. I would think that the internet traffic is routed through a CDN's reverse proxy, then filtered. This ...
1
vote
1answer
121 views

Fortigate Creating Millions of DNS events to standard domains

I am trying to tune our SIEM and noticed that we are receiving millions of DNS records every day from the same domains. These are: update.microsoft.com swscan.apple.com softwareupdate.vmware.com ...
0
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1answer
39 views

Debating between architecture options for offline updating of Linux machines in a vertically segregated network

My coworker and I are discussing the pros/cons between two potential architecture options, and I would like to gather feedback on which option is better and why. First, a description of the ...
-1
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1answer
46 views

threat intelligence gateway [closed]

A TOG (threat intelligence gateway) is a hardware piece that sits between the router and the firewall. The TIG uses the threat intelligence and filters out the malicious urls and IPs before reaching ...
1
vote
4answers
158 views

Given a set of ports is there one that is more likely to bypass a firewall?

I've been trying to solve a homework question in a beginner infosec class, and I was stumped on an issue and I didn't really know of the right place to ask. If it isn't then please let me know. Given ...
0
votes
1answer
49 views

Configure Windows Firewall Inbound Rule for Program Not Installed on Server

How can I configure an inbound rule on a Windows Server 2016 firewall to allow access from a program which is not installed on the server? When searching for a program browse is only offered for ...
2
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0answers
87 views

Non-upgradable usb device against badUSB

Lot of posts about badUSB (here and there) suggest to use a PS/2 connector for mouse and keyboard or to whitelisted USB devices or even use a hardware firewall that only allows whitelisted commands. ...
0
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2answers
63 views

firewall behaviour

If a client connects to a server he will start listening for the response on some random high port number. The client then expects any packet destined for that port to be a valid answer. Or does he ...
1
vote
0answers
48 views

apache struts 2 s2-057 does not return shell? [closed]

I do a pentest for a private server protected by Cloudflare. I bypassed the WAF and got the real IP for the server, then I scanned it with Acunetix and I found: Apache Struts2 Remote Command Execution ...
7
votes
1answer
2k views

Is it possible to detect DPI (Deep Packet Inspection)?

If one suspects one's packets are subject to DPI, how can it be detected?
1
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0answers
42 views

'Hard-to-guess' custom header (or similar) to whitelist via a firewall

My organisation is adding a firewall to our test stacks, using AWS WAF. We'd like to whitelist all traffic from the SDKs we've built to facilitate requests between our services. We thought of doing ...
20
votes
3answers
3k views

Why is it called a stateful and a stateless firewall?

I'm just wondering about the naming of these firewall behaviours. My basic understanding is that stateful filtering lets inbound traffic to return the outbound response without explicitly specifying ...
4
votes
7answers
148k views

How to effectivily block torrents on my network?

As per the network policy, we have to block all torrent traffic from the network. To do this, I used to block all ports above 1024 on my firewall/proxy devices. But due to this, many other ...
0
votes
1answer
65 views

How to close port 445 (Apple Time Capsule smbd)

My default configuration of Apple Time Capsule has port 445 (Apple Time Capsule smbd) open to the world. Online port scanners (shodan/detectify.com) show me that this. What's a bit worrying is the ...
9
votes
2answers
17k views

Is opening both TCP/UDP less secured than just TCP or UDP when needed and why?

If application needs opened port X UDP, or X TCP combination. Is there any potential risk by opening both UDP/TCP as I usually am not sure which one the application uses?
0
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1answer
88 views

Types of firewalls to implement to reduce DoS attacks in POS systems

Would you need an internal, external and a host-resident firewall for each POS client?
-1
votes
1answer
54 views

Would a firewall contain an explicit allow rule at the top?

Someone in an interview today told me every firewall has two rules: explicit allow at the top and explicit block at the bottom. Form the way I've always understood things firewalls are normally set to ...
0
votes
1answer
35 views

Stateless Firewall configuration and random port number from server

When I was reading about web servers, I came to know that though servers listen to static port (say port 80 for http), immediately after the connection, they assign a different port and thread to ...
6
votes
3answers
13k views

How to directly connect to devices behind NAT from the internet?

We have an IP address on the global internet: "A" We only have access to "A". We have a network behind a router that does NAT: 192.168.1.0/24 There is a client behind that NAT: "B" We don't have ...
-2
votes
1answer
54 views

WAF or Firewall [closed]

I am looking into putting a Firewall in front of our web servers. But we just recently implemented new next-gen firewalls. Does it make sense to put a WAF in front of our web servers as well?
1
vote
1answer
435 views

Why won't ossec block SSH connections when it seems to be configured correctly?

Why won't ossec block connections from another server? I installed ossec version 2.9.3 on Ubuntu 16.04. In the ossec.conf file I have these lines where x.x.x.x is the IP address of a second Linux ...
0
votes
1answer
317 views

Differentiating between IKEv2 and OpenVPN Traffic

There is a WiFi network that I regularly use, and it seems to be blocking all VPN traffic other than IKEv2. I tested this by downloading many of the free/freemium VPN apps from the Google Play Store ...
0
votes
1answer
51 views

Even though my firewall is active, is it protecting me fully given that the 'rules' are not active?

Even though my firewall is active, is it protecting me fully given that the 'rules' are not active? Output shows: host based firewall active, empty rules iptables modules loaded, but no rules ...
4
votes
2answers
8k 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
votes
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 ...
0
votes
1answer
129 views

Packet Filter with Access Control List

Can anyone explain how to read and understand row 1,2 and 3? My understanding for row 1 is : If any inside packets want to go to outside via any source port to destination port number 80 using HTTP ...
1
vote
0answers
47 views

Inbound rules for a port is configured and disabled yet an NMap scan shows that the port is opened

I am new to Windows Defender but have read about it to understand the basics of Inbound/Outbound rules. As mentioned on the app, Inbound connections that do not match a rule are simply blocked. For ...
2
votes
1answer
119 views

Can a firewall recognize (and block) outbound traffic that consists of screen shots?

I recently watched this YouTube video about capturing webcam image traffic using Wireshark. Although the technique used in the video is not applicable to my question (because it is about a MITM ...
1
vote
0answers
47 views

Securing a SOCKS5 to SSH Tunnel on Windows

In order to gain web access from the perspective of a remote device, it is very common to use the SOCKS5 to SSH Tunnel capability built into OpenSSH Client and Putty (detailed here). Both clients ...
0
votes
1answer
68 views

Is it possible to DDos a http wan filterd router? [closed]

Like the service is there but it's just filterd enabled for lan access only .. what will happen ?
0
votes
0answers
24 views

How to bypass egress traffic filtering for a reverse shell? [duplicate]

Say I have access to a linux server as non-root user (gained RCE using an exploit), say I am only able to run commands via http in bash/sh but I'm unable the to make the targeted server connect back ...
50
votes
7answers
56k views

With IPv6 do we need to use NAT any more?

I'm wondering how to use NAT with IPv6. Seems that you don't even need it any more. So what exactly is the concept behind firewall configurations in IPv6 environments?
3
votes
3answers
294 views

Web Application Firewall using web app source code analysis

I read this page: Category:OWASP Best Practices: Use of Web Application Firewalls, and I found that WAF cannot generally detect logical attacks. We know each web application has a number of input ...
1
vote
1answer
455 views

WebRTC.Local.IP.Addresses.Disclosure

We have Fortigate perimeter firewall and today i detected this event. What should I do to improve protection? How can someone take local IP address' through a Firewall? The following intrusion was ...
3
votes
2answers
133 views

How do I prevent traffic on my site from a source other than Cloudflare?

I use Google Cloud Platform to serve the site I manage. I have one load balancer there, which controls the movement to several virtual machines. When I came across the problem of DDOS attacks on ...
2
votes
0answers
56 views

Secure AWS instance metadata against potential SSRF

I am running a Windows instance on AWS. The instance has an IIS service running on it. The IIS service has a user associated to it and it has no need to access the AWS instance metadata. I was ...
0
votes
3answers
1k views

explorer.exe outbound (Unexplained TCP Connections)

So I've already disabled SSDP Discovery in Windows Services. I'm also not conducting any searches. I also have file indexing disabled on my system. I noticed a number of outbound connections coming ...
0
votes
1answer
54 views

Are there any alternative methods for reverse connections that bypass firewalls?

I'm doing a PenTest on a server. I have an RCE vulnerability on it, but when I try to do a reverse connection via netcat, the firewall blocks it. Is there any other methods used for reverse ...
6
votes
3answers
6k views

Firewall Configuration Audits

I'm looking to perform policy audits against firewall configurations and/or rulesets. This should be performed independently of any configuration management systems, ideally by operating off the ...
-1
votes
1answer
77 views

Firewall logs with Local IP contacting local IP over the internet [closed]

I noticed some wierd behavior in our firewall logs: a computer in our subnet 192.168.1.0/24 sending UDP packets in port 161 to an IP in subnet 192.168.20.0 (we don't have a subnet like that), and the ...
2
votes
5answers
38k views

Port Scan Detected and Blocked! - Bitdefender 2014

I have Bitdefender Total Security 2014. Recently I have been getting the message/alert "Port scan detected and blocked". I did not care about it much until I getting more especially in a specific ...
5
votes
3answers
8k views

Should I allow communication on public networks?

I apologize if this is a newb question. Reading this prompt, it appears that I should check Private Networks and uncheck Public Networks. However, Windows defaults to the opposite being checked. Am I ...
3
votes
1answer
228 views

How can Nmap bypass Windows Server firewall rules?

I need to block all communication (inbound/outbound) from server A to server B (all ports/all protocols). Server A should communicate with every machine except server B. I can't place firewall rules ...
0
votes
1answer
119 views

For security purposes, can I use vpn with ufw to allow traffic only from the vpn on ubuntu?

Is this possible? If not through ufw then some other software or iptables? How should I set up the ip tables? Assuming my public ip is known (and I don't want to change it), would it provide complete ...
0
votes
0answers
33 views

Iptables ruleset changes when running a native vpn application

Is it ok for a native linux vpn application (from a famous brand among the vpn providers) changing your iptables ruleset each time the vpn activated? Consider that one of the rules which always ...
0
votes
1answer
34 views

In what situations / with what nodes should a node ping / not ping?

I was recently looking at a network in which the client-machines that accessed a webservice endpoint, but which could not ping the webservice endpoint. And there are other machines that can ping the ...
1
vote
0answers
121 views

Reverse shell working with kali 2016, but not kali 2019.2, using Metasploit ms08_067_netapi

I have an unpatched Windows XP Home VM, a Kali 2019.2 VM and an old Kali 2016 VM. Using Metasploit's ms08_067_netapi module, I'm able to successfully get a reverse shell but only on the old Kali VM. ...
2
votes
3answers
1k views

How to block I2P and Freenet to my network?

I am trying to find a way to block I2P and Freenet darknets in a corporate network. Does anyone know a way to block them (on firewall)? Do I need to close particular ports or block entry nodes (like ...