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Questions tagged [nat]

Network Address Translation, or NAT, is a method of remapping an IP address from one IP space to another (for example the internet to your local 192.168.x address) by modifying the IP address information in the IP datagram while they're in transit.

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Spoof my NAT IP as local address on server side

I'm working on a Hack the Box challenge (Grammar - Web challenge) where I have to bypass a 403 page. The site is using Apache 2.4 and I have already checked the CVEs relating to this version with no ...
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How to set up a beef hook on another VM's browser in a NAT Network in VirtualBox

I'm reading "Practical Web Penetration Testing". I'm using VirtualBox to run two VMs: Windows 7 with Mutillidae and KaliLinux where I want to use Beef. Both are connected to a Nat Network 10.0.2.0/24. ...
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Is a DoS attack possible on a single home connection when the ISP uses NAT?

Today almost all ISPs use a NAT system to assign more people the same IP (at least where I am), probably because the IPv4 addresses are ending and they want to save money. Is it possible to make a DoS ...
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How to detect a DoS attack if today all use network address translation?

If a basic DoS attack can be handled by limiting the number of connections that occur in a interval of time with one IP and some enterprises and institutions use network address translation with many ...
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1answer
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IPsec Transport Mode NAT Traversal Security Risks

The strongSwan FAQ states: NAT-Traversal with IPsec transport mode has some inherent security risks. What kind of security risks is the documentation referring to? (links to other resources are ...
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Can ISP distinguish/identify devices behind NAT?

Let's say I have a PC and a smartphone, both connected to my home router. Scenario #1. The PC and the smartphone have VPN client installed on each device. Both devices connect to the same VPN server ...
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Nmap only detect virtual hosts and not physical hosts (maybe segmented network)

When my network settings is set to NAT and interface is eth0, this is the output of a simple nmap scan root@pc:~# nmap 192.168.0.0/24 Starting Nmap 7.60 ( https://nmap.org ) at 2018-03-04 18:47 EST ...
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Why is NAT referred to as “the poor man's firewall”? [duplicate]

How exactly does NAT protect a network? How does it relate to a firewall?
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IPv6 and NAT firewall effect

It seems that people still argue on whether to use NAT with IPv6 for its side-role as a firewall hiding inner network from the outside (providing user anonymity and security as well). I am wondering ...
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1answer
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Why do cellphones not use software to simulate a NAT router between the phone and the internet?

Connecting through wifi adds the benefit of being behind NAT. Why do cellphones not simulate being behind a nat network when connecting directly to the internet to limit the attack surface? Or, is ...
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321 views

Using IPsec through NAT

I have read that it is recommended to encapsulate IPsec packets into UDP (port 4500) packets in order to circumvent NAT. Could anyone please provide a detailed explanation of the reasons behind this ...
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44 views

How to defend against attacker without affecting other users of same NAT gateway

I am implementing a web service and have a daemon process that notices repeated failed login attempts from any given source. If too many occur the IP address is blocked for a given time. This is ...
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Is DHCP spoofing ever possible on VMware?

So I've just watched this Defcon video:https://www.youtube.com/watch?v=RaA5dEIqzzQ&t=1583s. Apparently they were able to set up a rouge DHCP server and get a 50/50 chance of sending the victim the ...
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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 ...
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1answer
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Client security using UDP

Introduction I am currently trying to build up a networking layer for Unity from scratch. Currently I am testing the communication via UDP using Node.js for the server and the client. However I guess ...
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Meterpreter (Metasploit) anonymous reverse connection over Tor2web

The general consensus seems to be that one sets up a listener on a server accessible by a public IP and some port forwarding. For anonymity this should be a throw-away server or a hacked box. I've ...
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361 views

How can a website block IPs behind a NAT?

Will a website be able to block my IP address alone somehow, while I am running a security tool behind my NAT? Or will it block my ISPs gateway IP?
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how to block pop up with iptables

Although I have enabled the pop up blocker in firefox, there are many websites that are able to circumvent this feature. (for example movie streaming sites like kinox.to). My question is not really ...
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1answer
217 views

Port forwarding border router security

Few days ago I was asking where to place the OpenVPN Access Server to provide network conectivity to LAN resources for remote users. While looking at the admin guide one of the few options is "One ...
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1answer
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NAT Mac address leak to Internet

Recently in the leaked 0-day exploit for Tor browser, whole shellcode's purpose was getting user's MAC address and sending it to the servers which people are suspecting that exploit was developed by ...
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IoT devices with public IP?

My understanding of worms like Mirai is the following: Try to telnet/ssh into random IPs using default user/pass credentials from various router/IoT manufacturers If you get in, do Bad Things™. It ...
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1answer
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Detecting Router (NAT) via port scan

I am developing a simple port scanner using Python, Scapy, nmap module. I want to detect if the host which I apply the port scan is a router or not. How can I identify or guess if the host is a router?...
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How does malware get past NAT routers?

How does malware, like the software used to create the botnet that recently DDoS'd Dyn, get past NAT? On a computer, I can see the user can be tricked into downloading untrusted code, or browser ...
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packets coming out of a 10.10 network with 192.168 source addresses

Since there are only a few different source addresses and they are all within valid subnets for the types of routers on our network (mostly netgear & mikrotik), I assume this means that this ...
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How to attack a specific computer on a remote network? [closed]

In a situation where I know the victim's public ip of their router, how does an attacker attack a specific computer in that network using something like metasploit? Because when using metasploit in ...
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Applicability of Same Origin Policy (SOP) when IP address is remapped via NAT

When an inbound/outbound TCP/IP traffic is faced with NAT address mapping, it's perfectly possible to have a different IP address as your request origin every few minutes. This is how most of the ...
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Scan a computer behind NAT

Network Address Translation resolve the problem of limited IPv4 by allocating one public IPv4. When a node inside the network want to send a packet to the internet a special port is generated that act ...
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Metasploit to connect to a target behind NAT

During a pentest and I experienced a weird problem with connecting to the target machine which is behind a NAT network the scenario is basically, they have a public ip : 1.1.1.1 and there are ...
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Shouldn't we all be protected by NATing?

Because of NAT, almost all users now are accessing internet via private IPs, and that's happening whether the users are behind a simple home router, or a complex proxy server. So, and as I understand ...
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4answers
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How can my IP camera be hacked behind a NAT?

I keep reading about hackers accessing laptop and home security camera systems. Most home users are using SOHO routers meaning they are on a private IP range behind a NAT. I realize NATs aren't ...
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1answer
659 views

How to access or scan a specific computer in a different network [closed]

I want to scan the ports of my neighbor's computer. I know the global IP address. However I can scan only the router, not the computer in the network. Is it possible to scan a computer in a different ...
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3answers
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Is a router without inbound firewall a security issue across the internet?

Imagine this scenario: Alice has a private subnet (192.168.1.0/24) connected to a router which is also connected to local network B. Alice's router performs NAT (only using MASQUERADE; outbound ...
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1answer
319 views

Multiple users sharing the same IP

I'm setting up a quite unusual proxy for a very specific niche case. I'm allocating (ip,port) addresses to users, from which they can send and receive UDP and TCP packets. e.g. say someone is ...
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4answers
2k views

How to find public IP, if it replaced by NAT IP?

I designed a network architecture in cloud. I placed first IPS and then firewall (with Nat). I want to know if some attacks gone to internal networks which are not blocked by IPS. But I think these ...
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2answers
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How to restrict access to the internet for some computers on the network?

I’d like to differentiate machines (or, possibly, users) on my small business network so that only some of them have access to the internet. The solution I’ve been using to this day is quite terrible: ...
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1answer
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Vulnerabilities of pure NAT without firewall

Following some of the comments on this question, I was curious about the security vulnerabilities of NAT. There are similar threads here and here but they discuss router vulnerabilities rather than ...
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2k views

Does NAT really provide security? [duplicate]

I had an argument with someone on IRC about Network Address Translation. I was under the impression that NAT provided a layer of security to internal networks. I understand that's not the primary ...
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2answers
2k views

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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461 views

How does malware performs a UDP hole punch?

I want to know how do malware like ZeroAccess hole punch the network without using a external server? Or do they just mainly infect non-NAT users? Does that mean all NAT users are safe?
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1answer
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Can NATs and firewalls blacklist IPs when trying to UDP hole punch?

I am developing a P2P application that will make use of UDP hole punch to connect two peers behind NAT. When dealing with connections between a cone and a symmetric, unpredictable NATs, however, hole ...
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4answers
3k views

How do CC servers communicate to botnet bots in a local network?

A more general question How do bots communicate in the Zeus botnet? doesn't really address my question. I'm trying to understand how a bot can communicate with command and control (CC) machine. On a ...
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2answers
1k views

How can an attacker access a system with a private IP address? [closed]

I am confused about this concept if a public IP is assigned to my router and my system has private IP address, how an attacker can access my system or can use my system as a BOT. Its a common scenario ...
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How can I obtain the internal IP of a computer behind NAT but reachable via certain TCP port?

I want to obtain internal IP of a remote computer behind a NAT that I can reach by using some port, say myhost.farfar.away port 11122TCP: C:\>telnet myhost.farfar.away 11122 SSH-2.0-OpenSSH_6.6....
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1answer
138 views

Should reverse connections be used to bypass NATs?

I'm planning on doing a demonstration on how remote administrative tools work for my schools computer security club. I plan on writing a RAT in C++ and demonstrating/explaining how it works. I ran ...
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2answers
4k views

What happens when a spoofed source IP packet is dispatched out of a private network with NATing

Suppose as an attacker i want to carry out a Ping or SYN Flood attack.. I can change the source IP of the packets generated at my machine to a false/spoofed public IP address so that replies go to ...
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1answer
2k views

Setting up NAT with firewall for RDP connection

I have a vendor who needs to connect remotely to one of our servers. What I thought I would do is setup a NAT rule in our firewall. I have a public IP address that I will have translated to the local ...
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2answers
10k views

How to detect Network Address Translation (NAT)?

How can I detect if NAT is used in network or not? I know if you have a private address and you are able to connect to a public network or the Internet, then there must be NAT. But how can I detect ...
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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?
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How can you (anybody) find out the IP address of a single computer inside college

How can you find out the IP address of a single computer inside a college network. Every computer has the same public IP address on the network. How is it possible, after discovering that the IP is ...