Questions tagged [nat]

For questions about Network Address Translation (NAT), a method of modifying network address information in IPv4 packet headers.

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Does UDP hole work if server is on the same subnet? [closed]

I am trying to get a minimal NAT hole punch example working. I think the problem is that the Server and one of the clients are on the same subnet. For that client I only see some local ip from the ...
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35 views

Issue w/ Cisco router and failed NAT and static default route

I have a cisco router that is using a VRF to support a site to site VPN tunnel. I have added a second network to the router for non-VPN standard internet use. My problem is that my default static ...
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How Does Network Address Translation Work Initially at the End Point Router

I have come across a question that I can not seem to get a quality answer to. I understand how NAT works when a reply packet is received and how it is mapped back to an internal IP address from the ...
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How can IoT devices be remotely accessible despite not having any open ports on the router? [closed]

I know the methods used for this won't be exclusive to IoT devices, but my post is about them because they make things a little less abstract. So to my understanding there's two methods that are used ...
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Static port forward 1194 to VPN server behind Cisco router

I'm trying to setup a VPN server behind a Cisco router which is my main internet gateway. I've set it up as shown in the attached picture. The problem I'm observing is that zero packets with a ...
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Why doesn't NAT drop packets with spoofed public source IP?

As I read on Section 4.3.8 of this page https://www.manrs.org/isps/guide/antispoofing/, The following code: ip nat inside source list INSIDE pool OUTSIDE overload will translate packets with a ...
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1answer
24 views

Cisco ASA NAT/PAT Multiple WAN IPs

I'm trying to setup a NAT / PAT in ASA 5520, I'm able to do so very well when the Public IP I want translated to Internal host is configured on the Outside. Question is the ISP provided 1.1.1.1/30 ...
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Why does Network address translation (NAT) need Port Address Translation (PAT) if IPs are different in the internal network?

For example, there are several servers in the local network 192.168.0.1, 192.168.0.2, 192.168.0.3, etc. They are connected to one public IP. Why does NAT also assign ports to each local IPs that are ...
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Do NAT devices need to have private IP addresses?

If a NAT's job is to create mappings between internal ip/port pairs and external ip/port pairs with one Internet-routable IP address, does a NAT need a private IP address for itself? I think one ...
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Debug ip nat in IOS XE

I used to use debug ip nat in IOS to show NAT translations happening. On a Cisco C1111-8P running IOS XE, this command does not exist anymore: router#debug ip nat % Incomplete command. router#debug ...
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What's the difference between “IP NAT Inside Source” and “IP NAT Inside Destination” commands in Cisco routers? [duplicate]

As much as i know both of this commands translate source address of packets that travel from inside to outside and destination address of packets that travel from outside to inside,so what's the ...
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Cisco ASA static nat one-to-many from interface address to object-group

Syntactically, the following set of statements is valid (at least as of 8.3): interface Ethernet0/0 nameif OUTSIDE ip address 192.0.2.1 255.255.255.0 interface Ethernet0/1 nameif INSIDE ip ...
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1answer
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Prevent static NAT to respond to ARP requests

We are trying to merge 2 networks with overlapping IP spaces: This is the configuraiton so far: interface Tunnel1 description VPN Port CompanyA ip vrf forwarding LAN ip address 172.18.0.79 255.255....
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23 views

Segregated network - managed switch or router?

I have 3 pc connected to a switch that is connected to a bigger network. I want those pc to live in their network and don't expose their ips. (in this very moment the scope is accomplished using a pc ...
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When a packet is received, how does it know which internal machine to send it to?

I am familiar with ARP and routing, but I think I am failing to put two and two together here. On an IPv4 packet we have the source IP address, which allows any router to send the response back to the ...
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52 views

Why can some people use public ip address to access a server from an internal network with the client device within the internal network

As the title suggests. I find it mind breaking to think how network architecture can differ to allow/not allow using public IP address to access a server within internal network from within the ...
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Ipsec connection and nat only one site [duplicate]

There are two companies and two of them connected to each other with İPsec vpn. Company A has a server and company B want to reach to company A server. Which company need to configure nat on its ...
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NAT translations showing up on router but end-host cannot ping ISP

When an endhost (192.168.40.3) on VLAN 40 pings 172.27.47.30 (NL1-BS fom ISP1), a request timed out message is given. However, the "show network translations" on R1 has a translation entry even though ...
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39 views

When is NAT Masquerading required?

I'm learning about NAT Masquerading and I'm a bit confused about when you would want to Masquerade. I've seen examples of using an interface for a VPN tunnel and how something like that on a router ...
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Packets lost with correct TCP sequence number. Is it possible?

I'm analysing some communication issues that we have between a server (SCADA) and remote terminal units (RTU) that we have in the field. The communications are IEC104 protocol which use TCP/IP. The ...
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NAT overload and access to web resources

I have really bizarre problem in clients network. Clients have access to the internet via NAPT - I'm using several public ip addreses for this purpose. (I'll change ip addresses for obv reasons) ip ...
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3answers
98 views

Single-homed connection to ISP without NAT feature

Is it possible to connect my private network to the ISP router without a Network Address Translator (NAT) feature enabled on my router? As I understand, in a single-homed scenario connection to ISP, ...
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1answer
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Is performance worse routing between two vlans on one interface than routing between two NICs with no vlans?

I have a Linux router with one interface that is connected to a switch in port 2. Port 2 on the switch is a member of vlan2(ISP) and vlan3 (office devices). My router is currently routing between ...
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Does NAT violate end to end argument?

Does NAT violate end to end argument? What does end to end argument means in this context?
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How to configure an ACL on ASA when the inside source IP address is translated by NAT? [closed]

I don't know how to configure an ACL when inside source nat is enabled. In my example, I want to realize bidirectional communication with TCP port 30000 between 172.16.100.100(inside) and 10.10.10.10(...
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124 views

Active Directory and DNS over NAT

I'm planning to apply the network address translation on a router between hosts and AD/DNS server in an organization. It seemed that this scenario is complicated for a private network. The topology ...
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285 views

BGP and NAT Not working

I have an odd issue with BGP+NAT. I have 2 separate routers and 2 different ISP's. Topology looks like this: ISP1--BGP--> RTR1 \ \--OSPF-- Palo Alto Firewall-- Internal ...
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LAN to WAN IPv4 address mapped to LAN server through NAT Rules or other

I need to set a rule that allows me to connect BOTH from OUTSIDE the LAN (from the "internet" to the Internal server at IPv4 address 10.64.0.50 via port 22, by running ssh://1.2.3.4 -p 22; AND From ...
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28 views

NAT on the endpoint

NAT is normally performed on the router to translate addresses from one network's address space to another's. Is there ever a reason to perform NAT directly on the endpoint instead? For example, if ...
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1answer
133 views

How does NAT ensure that every machine has a unique public IP?

I am trying to understand the distinction between public and private IP addresses in IPv4 networking. The picture I've been told has some problems with it, so I would like to present it here and ask ...
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How To Route Private Subnet Traffic To Internet Via Public Subnet In The Same AWS VPC?

This scenario is simple, created a VPC (CIDR > 172.16.0.0/16) in AWS Management Console, created 2 subnets in it. Public (CIDR > 172.16.1.0/24) Private (CIDR > 172.16.2.0/24) Public route is set on ...
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How does a DNS response reach a client behind a NAT?

How does a DNS response reach a client behind a NAT? I'm talking about DNS queries using UDP for transport with a server that is not in the same network as the client. Does the NAT correlate the ...
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109 views

Static PAT using Cisco ASA 5506 in cisco packet tracer [closed]

ciscoasa(config)#interface GigabitEthernet 1/3 ciscoasa(config-if)#nameif inside1 INFO: Security level for "inside1" set to 0 by default. ciscoasa(config-if)#security-level 100 ciscoasa(config-if)#no ...
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Is it possible to see the NAT or PAT mapping from the firewall logs?

Is it possible to see the NAT or PAT mapping from the firewall logs? For example a Fortigate. Thank you This is my previous question which I cannot edit. But here I am posting a precise question. ...
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53 views

Cisco IOS RA VPN with internal NAT

We have a Cisco 871 setup with a remote access VPN which works fine. However we now need the RA-VPN to be able to access an IP on the LAN which only speaks with an authorised subnet. IP addresses as ...
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1answer
17 views

Connect VPN with same Private Network [closed]

i have my Private Network on my Apartment that is 192.168.1.x/24 and in the Office we have Private Network 192.168.1.x/16. Is it possible to connect them through VPN, but i will not change my private ...
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IPsec tunnel with multiple networks NATed [closed]

I'm trying to set up an IPsec connection between two sites: our Azure network and our client's local network. To be flexible and avoid any current or potential future IP range overlappings I wand to "...
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1answer
104 views

Meraki firewall MX64 how to do two IP seperated inbound NATs

I need to achieve the same result of these two commands which are on Cisco CLI but on Meraki GUI so we have two valid public IP address(81.1.1.30,31) on outside interface of MX64 both of 'em want to ...
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93 views

Nat ACL Question?

I am so confused with fundamentals that I used to be an expert in, so I have this topology Please answer to my questions separately, Question 1) So if I have two DNS severs, and ofc two IP address(...
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455 views

How to connect multiple devices with identical static IP into a wireless network

I've been searching StackExchange and the Internet for a while looking for a solution for my networking question. Some articles I found are here, here and here, but these don't need to deal with a ...
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1answer
64 views

IP address source and destination translation without a gateway

I have a private network (no gateway) with a number of devices configured on one subnet (say A.A.A.0/24). I would like to change the IP addresses of all devices on this network to a new subnet (say B....
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outside NAT isn't working?

Should static NAT using "outside" work the same as "inside" Topology: For example, say I use: ip nat inside static source 192.168.1.1 10.1.1.50 I try to ping 10.1.1.100 from 192.168.1.1 source ...
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192 views

Is UDP Hole Punching possible if the network of one peer has multiple external IP addresses?

I've developed an implementation for UDP hole punching that works for most use cases that I've come across. However, one of our offices has a network configuration where we have two ISPs providing us ...
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239 views

How to connect four networks with overlapping addresses?

We have four networks for four departments: R&D, Sales, admin and finance. All IP addressing is from the 192.168.1.0/24 network. So, maybe four PCs have same IP address, e.g. 192.168.1.8. Now, we ...
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300 views

TCP connections hang during handshake [closed]

For the last few days, connections originating behind my LAN's NAT have been having issues completing the TCP handshake (i.e. web pages only load after hitting F5 a few times, network applications ...
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1answer
70 views

Setup VPN to access company's internal network without NAT [closed]

Below is how the network looks like, the left is my home, and the right is my office. Now I want to connect to office intranet(192.168.0.0/24, R3). We don't have any vpn device that directly connects ...
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188 views

What does NAT64 do which can't be done by deploying IPv6 + NAT444?

Why was NAT64 developed? What does it do that can't be done by deploying IPv6 + NAT444, and allocating your customers a (public) IPv6 and a (private) IPv4 address (behind a shared public IPv4 address)?...
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39 views

Origin of Cone in NAT naming convention

I am reading about Full Cone, Restricted Cone and Port Restricted Cone NATs. While how they work is clear, I am having trouble coming up with a justification for such naming. The "Cone" probably has ...
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1k views

Why isn't 10.0.0.0/8 used instead of 192.168.0.0/16 for private addresses?

RFC 1918 “Address Allocation for Private Internets” (https://tools.ietf.org/html/rfc1918) specifies 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16 as private addresses suitable for unrestricted private ...
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57 views

Difference Between PAT with pool or Interface/Loopback?

I'm just wondering what difference does it make when doing PAT with same IP defined in pool or assigning IP on Loopback and overloading that interface. ip nat pool MYPOOL 1.1.1.1 1.1.1.1 netmask 255....

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