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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Problem with Configuring Selective DNAT for HTTP Traffic on Fortigate Firewall

I'm currently in the process of setting up a new Fortigate Firewall and have run into an issue while configuring DNAT. From what I understand, this is done through Virtual IPs in Fortigate. My goal is ...
Mischa-H's user avatar
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Host Based Load Balancing on Multihomed Networks [closed]

I've been struggling to understand the best practice for load balancing (per host) on multi-homed networks. Ensuring that the load balancing is based on the host is crucial because sessions do not ...
Brandon's user avatar
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conntrack expectation on directed broadcast [closed]

I'm testing out a setup that I would reproduce in a production environment if I get it work. What I have: A wireless network 192.168.88.0/24 An IoT device X in the wireless network A Teltonika router ...
path's user avatar
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FortiGate IPSec - both sides behind NAT [closed]

my situation: i have two virtual fortigate Firewalls wich are both behind a Fritzbox via WAN Port. Now i want to configure an ipsec connection between these two fortigates. (both sides have a dyndns ...
Julezzz's user avatar
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2 answers
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How to connect TCP server behind NAT

I need to establish TCP connection with a server located behind the NAT. The simple solution is to reverse the connection and ask the server to connect to the client, but then I am unable to use ...
Grzegorz Ka's user avatar
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Clarification of external interface vs source interface filter in Fortigate DNAT/VIP

On a Fortigate firewall, one can configure Destination NAT using the DNAT & Virtual IPs section of the GUI, or the config firewall vip section of the CLI. When you create a DNAT object using ...
jimbobmcgee's user avatar
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Problems with twice-NAT on Cisco 3548

I'm trying to get Twice-NAT working on a Cisco 3548 switch. I have a VRF set up with 2 L3 ports on it - Eth1/33 has ip address 20.20.255.250/16 and is nat inside Eth1/34 has ip address 10.10.1.211/24 ...
Kevin's user avatar
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How to remote access CCTV's device behind CGNAT for IPv4, and device doesn't have support for DDNS IPv6? [closed]

TL;DR Multiple locations with local CCTV. How to remote access all of them, with an ISP that services IPv4 behind CGNAT and the DVR doesn't supports DDNS for IPv6. DVR also offers API, SDK, P2P and ...
Justcurious's user avatar
1 vote
1 answer
76 views

Why can't we use large-scale NAT system with thousands of private IP addresses assigned to a single public IP

Instead of assigning everyone an individual public IP address, could we use a very strong NAT system with thousands of private IPs behind a single public IP? This could reduce public IP demand and ...
Arash Seifi's user avatar
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2 answers
113 views

How to apply a Route-Map to a NAT connection

I am following a tutorial about route-maps on youtube. https://www.youtube.com/watch?v=2YlsXcT1Pjw There is this topology. The default route on R1 points to 10.10.10.2 In the video he just shows how ...
mbrain's user avatar
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2 Routers for PPPoE and NAT 5 Public IP [closed]

My ISP have provided me with 5 Public IPs. I tried to NAT these 5 IPs to our local server by using this setup. The primary router will be setup for the internet connection while the one-to-one NAT of ...
Renivle's user avatar
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2 answers
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Communicating to a device with a random IP, Subnet Mask and Gateway

I think am looking for a way to reliably communicate with devices connected to the network with "wrong" configurations. Our company sells products that can have their network settings ...
nickolaij's user avatar
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1 answer
375 views

How to use 5 static ip addresses with virgin media broad band

I have installed virgin media business broadband and the package comes with 5 static ips. These IP are GRE tunnels from the HITRON router to virgin. the IP addresses are for example 66.66.66.65 - 66....
funkimunky's user avatar
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Simple question about NAT [duplicate]

So I am learning about NAT. I understand that it changes IP from public>private and vice versa. From my understanding, when a packet or info gets sent to the public ip towards the private ip, ...
yea im a noob's user avatar
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1 answer
165 views

Communication between hosts on different local networks

I understand how NAT works in case of communication between one, local host and a server with specific public IP address. The host is sending a request, it pushes the packet with destination IP ...
Bratw's user avatar
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How to forward UDP unicast messages to multiple destinations [closed]

I am trying to forward a UDP Unicast message so that it cant be received by multiple computers. Can anyone point me in the right direction for how to accomplish this? Here are the details: There are ...
James Duvall's user avatar
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Is internal network traffic sent to private subnets via their NAT Server?

Similar to this question, I'm wondering how resources in my public subnets communicate with those in my private subnets - when there is a NAT service present. My impression is that a self-managed NAT ...
d8aninja's user avatar
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NAT configuration behind pppoe with virtual server

my CISCO 3925 router is handling pppoe, NAT, and DHCP server.. My local LAN is 192.168.1.x and it's behind that NAT. I'm trying to enable access to a DNS server that's on this LAN (192.168.1.191 tcp/...
Turgut Kalfaoglu's user avatar
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3 answers
222 views

Can I use the network and broadcast IP addresses of a /24 subnet, when the /24 subnet is included in a larger /22 subnet range for NAT?

I'm wondering if I can use the network and broadcast IP addresses of a /24 subnet, when the /24 subnet is included in a larger /22 subnet range for NAT? PS: Please consider that 198.51.0.0/22 is ...
Ulteara's user avatar
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Connect site-to-site private networks [closed]

I used VPN to connect site-to-site private networks from A to B. It worked fine. Then I used NAT for (1) hiding private networks and (2) LAN of 2 sites could access the Internet. The problem is that ...
Gekko's user avatar
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Pfsense NAT with site-to-site VPN

For a client I am building a network solution that enables them expanding their available online presence. I am running into a problem with port forwarding to an IP which is routed over an OpenVPN L3 ...
Koen Vuurens's user avatar
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How to allow cisco to log on to a specific ip port using nat

Good afternoon, I use Cisco 7201 I create a network on the gi0/0 interface connecting to a dhcp provider and get a static ip address, also on the gi0/1 interface I create a network where my 5 servers ...
ImeanLhas's user avatar
2 votes
1 answer
340 views

Does UDP work with NAT

I'm learning the TCP and UDP protocols and I have a question about UDP. I used C to develop a UDP server and a UDP client in my LAN and it works as expected. The server and the client could ...
Yves's user avatar
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Hide private IP address

DS has 7 VLANs and 7 DHCP pools respectively. There are 3 trunk links to 3 access layer switchs to share VLANs. Its VLAN interfaces and DHCP pools: ip dhcp pool vlan10 network 192.168.10.0 255.255....
Gekko's user avatar
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ACLs block connection

Here is my configuration on ISP router: interface GigabitEthernet0/0/0 no ip address duplex auto speed auto ! interface GigabitEthernet0/0/0.10 encapsulation dot1Q 10 ip address 192.168.10.1 255....
Gekko's user avatar
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5 answers
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Are there any methods of differentiate between a single computer and a NAT router?

As far as I know, a traffic from a NAT router should appear similar to traffic from one computer with a single IP address. If you do not have any access to a network (let's say you are an ISP), can ...
jiwopene's user avatar
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2 answers
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If there's a NAT-capable gateway between WAN and a switch, why is a switch helpful?

To preface this question, my question is somewhat related to what I'm trying to understand as the difference between layer 3 switches and routers. The main difference between the two is that layer 3 ...
itsmarziparzi's user avatar
1 vote
1 answer
349 views

If your ISP already has a gateway, why do you need another gateway with NAT to come before a layer 3 switch?

Please bear in mind that I am learning and have never set up a network with routers and switches myself. Also please bear this is sort of going to be loaded question because there are multiple layers ...
itsmarziparzi's user avatar
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1k views

connect two private network using pfsense

I have two pfenses (say p1 and p2) in two separate networks. Each has a public IP. There is an internal network on each side (say n1 and n2). I want to connect these two networks through these two ...
horny hacker's user avatar
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Can somebody help me understand this static NAT example

I have the following example: From my understanding of static NAT the client makes a request on the inside global address of a resource, in this case the webserver. (http://209.165.201.5). The request ...
Rubus's user avatar
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3 votes
2 answers
163 views

in Twice NAT, why cant external network be advertised to private network?

This is from the NAT RCF: The following is a description of the properties of realms supported by Twice-NAT. Network address of hosts in external network are unique in external networks, but not ...
user86942's user avatar
1 vote
2 answers
66 views

Best way to configure for port forwarding

I am using a Peplink Balance 30 router. Right now I have only one public IP. I have set up the LAN for 192.168.8.1. I have five devices on the LAN side, including two Ubiquiti Rockets and three IP ...
Eric's user avatar
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0 answers
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IPTables how to nat 10.8.a.b to 10.0.a.b? [closed]

The problem -- Translate 10.8.a.b to 10.0.a.b ? I have a VPN setup to a bastion host. I'm attempting to map 10.8.0.0/17 into 10.0.0.0/17 so that the IP address 10.8.1.1 gets mapped to 10.0.1.1 in my ...
Christian's user avatar
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2 answers
130 views

Public IP Configuration which has a private gateway

I bought a public IP from my ISP and they provided me with the following details. WAN IP :10.129.69.157 LAN IP : 196.188.173.32/30 How do I configure this on my side ? The told me to do configure as ...
Tinsae's user avatar
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4 votes
4 answers
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Do I get any security benefits by NATing a network that's already behind a firewall?

I'm deploying a new network for IOT devices, this new network will be behind a firewall. I've been suggested to also get the network natted to further improve security. Does this really add any ...
Gaston539's user avatar
1 vote
1 answer
321 views

Why is it necessary to configure an ACL when configuring Dynamic Nat?

When configuring Dynamic NAT, why is it necessary for us to also create and specify an access list which dictates what kind of traffic should be translated? Couldn't we simply skip this step, so that ...
Mitrixsen's user avatar
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2 answers
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Could we use an IP address in our network that does not fall into the RFC 1918 range?

RFC 1918 specifies 3 ranges of IP addresses as private 10.0.0.0/8 172.16.0.0/12 192.168.0.0/16 So in a real network, only these IP addresses could be used? What if I assigned a host on the network an ...
Mitrixsen's user avatar
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How to NAT a unicast address to a broadcast address?

I have a 800-Series router connected in the following configuration: Port GigabitEthernet7 is connected to an external server (192.0.2.251) that sends unicast UDP to destinations 192.0.2.42:45100 and ...
O. Salah's user avatar
1 vote
1 answer
439 views

Cisco ASA not accepting external traffic without NAT configuration

First of all, I am quite newie in the cisco world, so this could be some easy stuff that I'm missing. My first problem is trying to understand why a Cisco ASA5585 does not show traffic while doing a ...
adrianlzt's user avatar
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0 votes
1 answer
46 views

When a new entry in the NAT table is created and an entry in the NAT table is removed?

When using TCP, is a new entry in the NAT table created when a connection is made? and is an entry in the NAT table removed when a connection is closed? If I am correct, what happens if both ...
user85187's user avatar
1 vote
1 answer
229 views

How can a port be both be used to identify a private IP, and also to connect to a specific service?

Sorry if im asking something nonsensical, im still trying to wrap my head around these terms. Heres my understanding NAT is the process of translating a private IP to a public IP, lets make an exaple ...
Mol's user avatar
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2 votes
1 answer
477 views

Site-to-Site VPN with BOTH sites behind NAT (mobile data routers)

I have 2 sites (call them "A" and "B") which connect to the Internet using 4G mobile data routers - don't knock them, I'm getting 200Mbps downlink and 30Mbps uplink, faster than a ...
kbro's user avatar
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2 votes
1 answer
107 views

Do NAT Gateways Need to be the First Address of the Network?

NAT gateways are often given the first usable address in an address space. Do any protocol specs require this? Or is this just a convention? I skimmed RFC 1918 and RFC 2663 but didn't see anything ...
Brett Holman's user avatar
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2 answers
174 views

How does NATing work

I'm not 100% understanding how NATing works. Let me setup our network and talk this through. So first of all, lets say that I have an IP size of 4 bits so 16 possible combination. The only private ...
Jenia Ivanov's user avatar
1 vote
0 answers
231 views

Full Cone NAT on Cisco router in Packet Tracer

I am trying to create a network with two subnetworks with private IPs. I need to configure symmetric NAT on edge routers within the subnetwork. Diagram: I need to configure NAT on Router0 and Router2....
Filip's user avatar
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0 votes
1 answer
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Is it possible to send network messages with "Fake" Local Network(192.168.x.x) destination IP but actually reaches the destination via internet?

I am configuring a MySQL server that is only intended for computers from internal network/local network machines to access. Now MySQL has a "bind IP address" setting that, if I set it to the ...
cr001's user avatar
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0 votes
1 answer
614 views

Cisco ASA VPN tunnel shows up (phase 1 and 2, MM_ACTIVE), but no traffic passes

My end of the tunnel is on an ASAv in AWS. (version 9.14) show crypto isakmp sa 4 IKE Peer: 212.239.x.y Type : L2L Role : responder Rekey : no State : ...
Chris Holt's user avatar
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0 answers
15 views

How are we still able to use IPv4 address even with NAT? [duplicate]

My question is why haven't we run out of IPv4 public IP as well because now almost all home has a router which is assigned a public IP. Is it possible to have multiple layers of NAT on the router-ISP ...
Himanshuman's user avatar
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1 answer
98 views

Why are External NAT ports different when both NATs are restricted cone? [duplicate]

I'm in the progress of implementing my own Signaling server with UDP hole punching, everything have been smooth up until both hosts were behind Restricted Cone NAT, then the ports for P2P ...
Blip's user avatar
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1 vote
1 answer
890 views

Checkpoint Firewall using wrong Source IP when establishing a VPN

I have a checkpoint VSX environment running r81 and I have a DMZ firewall that has two external interfaces. One that goes to the Internet and one that goes to a 10.0.0.0/8 network that connects to ...
The Footsie's user avatar

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