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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Two PC on the same LAN, communicating the same Server

Assume that we have 2 pc on the same LAN, local IP of pc1: 192.168.1.5 local IP of pc2: 192.168.1.6 Now suppose that both pc1 and pc2 wants to connect to a server on the internet, we all know that the ...
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DMZ host is not reachable from LAN [duplicate]

I have a pfSense firewall with WAN, LAN and DMZ interfaces. A server is residing in DMZ with private ip 10.0.0.2. Therese a 1:1 NAT in WAN interface that is mapping a public ip X.Y.Z.213 to 10.0.0.2, ...
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Double NAT issues? [closed]

I have minor networking experience (college stuff) and I'm not posting this looking for support to a problem, but rather am just wondering if there's validity to something I was told by a Verizon tech ...
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Testing DNS set on VM on host PC [closed]

I am new to this community. I am currently studying computer science and I am trying to practice some stuff here at home while locked. So at the university we have computers that are connected to the ...
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0answers
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Modem take place of my public address [closed]

I want to access my localhost remotely, my localhost ip & port is:192.168.1.3:8080. I did all necessary things(static ip, port forwarding...). Inside my network everything work properly so i can ...
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public static NAT IPv4 address also for outgoing traffic? [closed]

Since my ISP doesn't assign public static IPv4s anymore (but only IPv6), I bought a static NAT IPv4 address, which I use as my "public IPv4 address". The main reason I need this is that I'm ...
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1answer
22 views

Public IP address does not work in internal network [closed]

I have configured port forwarding to my system from the router configuration menu, when I try to access the public IP address in the internal network it does not respond but it is accessible outside ...
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2answers
52 views

Possible typo in Tanenbaum's book about NAPT

From what I have understood from multiple sources (web and other books) about the concept of NAPT (also called NAT overload or IP masquerading in Linux environment), if there is a scenario like the ...
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3answers
51 views

Static NAT and PAT

I have two private IP addresses, want to make them NAT to 203.0.113.0/2 public IP address. WAY 1 : Static NAT (2 ip addresses NATted to one by manually) WAY 2 : PAT (Router gives port number ...
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30 views

CMTS (DOCSIS 3.0) with CGN (CGNat)

For a new project/building I am working with the CMTS model MA5633-XB10 by Huawei. The usual way is done by implementing two DHCP servers in the same VLAN, from which the CPE gets the private IP ...
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2answers
83 views

What happens when a NAT router reaches its 65,535 connection limit to a specific destination?

If a company of thousands of end points all try to access a specific destination (let's say google.com), then the maximum TCP connections it can have in total is limited to 65535 connections, based on ...
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1answer
182 views

pfSense 1:1 NAT Not Working

Next year, if I have the money for it, I want to get a dedicated server (either from Hetzner or OVH) and some IPs (maybe like 16 IPs). The server will have Proxmox and VMs will get their network ...
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Why is symmetric NAT called “symmetric”?

After searching a while, I'm still not able to find a logical explanation on why it is called symmetric NAT. Where lies the link between symmetric NAT and that each request is mapped to a unique ...
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67 views

Cisco router on a stick with public ip wan (ISP)gateway

I am trying to create a router on a stick with an outside facing sub-interface with a public IP from an ISP. I have tried to configure NAT and routing but I just cant get to ping the internet. I'm ...
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1answer
55 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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2answers
81 views

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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1answer
55 views

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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2answers
39 views

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
28 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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1answer
39 views

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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2answers
58 views

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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95 views

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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0answers
37 views

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
52 views

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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1answer
24 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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2answers
61 views

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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2answers
60 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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10 views

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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53 views

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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1answer
44 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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79 views

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
130 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
33 views

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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3answers
2k views

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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0answers
32 views

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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1answer
374 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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3answers
340 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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1answer
115 views

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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1answer
31 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
149 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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3answers
77 views

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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1answer
77 views

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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0answers
151 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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1answer
34 views

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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1answer
54 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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0answers
49 views

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 "...
0
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1answer
125 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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