Questions tagged [nat]
For questions about Network Address Translation (NAT), a method of modifying network address information in IPv4 packet headers.
559
questions
0
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1answer
28 views
Need a little clarification with NAT and IPv6
I understand NAT exists to not exhaust all the ipv4 addresses so there is no need for it with ipv6. So with ipv6 having an unimaginable amount of addresses, will every device have its own public ...
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0answers
8 views
Nat Loopback | Nat Reflection | Nat Hairpin [closed]
I am using beetel 777vr1 , I done the port forwarding with help of friend. Now Issue is i am facing is I can access the website from the outside of network using my public/static IP. But when i try to ...
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0answers
10 views
Hairpinning on ORBI RB650 [closed]
I have a server that unable to access external IP Addresses when connected to LAN.
For example External Ip Address: 108.111.111.222
Internal Ip Address. 192.168.1.100
When connected to the same ...
1
vote
3answers
87 views
Trace internal equipement from Internet while answering
I would like to know if it's possible to achieve a traceroute of nodes on an internal network from an equipement on the internet answering to a query.
Let's say that a client on an internal network ...
0
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2answers
54 views
Is NAT66 a Viable Option to Protect Client?
Due to the addressing scheme of IPv6, each client now is able to get and directly use Globally-Routable Address (GUA) from the ISP. But that poses bigger security threat because attacker can directly ...
1
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3answers
72 views
Combining NAT an tunneling
I was reading a text and a doubt came to mind. Suppose there is an interface in a router that implements NAT. That same interface is the extreme of a tunnel. If I was to send a message through said ...
1
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1answer
27 views
How to Mitigate DoS by Bindings/Transport Address Exhaustion in NAT64?
Let's say a NAT64 Router only has 1 IPv4 address for bindings, meaning the NAT64 router has a roughly 65535 IPv4 transport addresses. A malicious attacker can then exhaust the entire IPv4 transport ...
0
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2answers
39 views
Why does IPSec's Transport Mode ESP can't be used in NAT64 although ESP doesn't sign the new IP header?
In RFC6146 stated:
Any protocols that protect IP header are incompatible with NAT64. This
implies that end-to-end IPsec verification will fail when the
Authentication Header (AH) is used (both ...
1
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1answer
19 views
Why does CLAT in 464XLAT architecture use Stateless NAT64 instead of Stateful?
As of my understanding, stateless NAT is using 1:1 translation, meaning it needs one IPv4 address for one IPv6 address vice versa, thus not preserving IPv4. Since the CLAT is supposed to be router/...
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2answers
39 views
General: What is a dynamic gateway, how does it work, where is it used?
I saw this option in my OPNsense gateway configuration, and was hoping someone could shed light on what it is, exactly:
Dynamic gateway policy: [YES/NO]
This interface does not require an ...
1
vote
1answer
41 views
Is an IPSec connection between 2 devices behind NAT possible?
We have tens of IPSec connections between our office and customer site's. We use an extra router in the customer network (so behind NAT) to initiate the connection to our office where a PFSense router ...
0
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1answer
32 views
How to connect to a machine which is sitting behind NAT router?
I have a server that needs to push a message to a client from which it received a request a few days ago. Now request which was received has the IP address of the NAT router behind which the client ...
0
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1answer
31 views
Cisco Port forward ip nat inside source static … Invalid
This is almost the same question as How to setup port forwarding on Cisco Router running Version 15.2(4)M6. The problem is that the command used in the answer is not available:
ip nat inside source ...
0
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1answer
51 views
Why does my enterprise issue me a public IP address instead of just a private IP address?
Let's say I work for a big enterprise organization. When looking at my IP address, I notice that it is not a private IP address but is instead a public IP address.
What are the benefits of ...
0
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2answers
54 views
NATTing a server address
I need help writing NAT rule for this use case: I want to be able to connect to an local IP as though it's the remote server IP. e.g. port forwarding.
I don't have access to the firewall on the remote ...
0
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1answer
29 views
Cisco NAT - Overload PAT and Static nat from one inside to two outside interfaces
i have following setup
Cisco ISR4k Router with one inside LAN interface and two outside Interfaces.
---- WAN1 (NAT outside)
LAN (NAT inside) -- ISR4k |
...
1
vote
4answers
71 views
port address translation
I was reading about different type of NETWORK ADDRESS TRANSLATION (NAT) techniques from a book, and was reading about a special type of NAT that is called port address translation, and it's known that ...
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0answers
24 views
Cisco: NAT overload does not work on Serial point to point interface /32 address on Cellular modem
I have a LTE modem installed in a Cisco 1921 that is able to connect to the carrier network and ping out sucessfully from the router, however NAT hosts are not able to connect to the internet.
There ...
1
vote
1answer
214 views
Destination NAT on Cisco ISR
I know how to perform regular overload PAT in my lab running
sh ver
Cisco IOS XE Software, Version 16.03.09
Cisco IOS Software [Denali], ISR Software (X86_64_LINUX_IOSD-UNIVERSALK9-M), Version 16.3.9, ...
0
votes
2answers
35 views
IPSEC between two offices with SAME local networks. How should I do nat? [duplicate]
I have two spokes with same local networks and want to do IPSEC between them.
When I try to ping 172.17.214.111 from 192.168.5.0 (from right side to left side) I see packet on Cisco router and I see ...
1
vote
1answer
76 views
PAT with multiple VLAN
I've set up a network with 4 VLAN, 3 VLAN configured PAT on it and 1 VLAN configured STATIC NAT. The router is acting as the DHCP server. Outside of my router I have another router acting as "the ...
0
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2answers
34 views
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 ...
0
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0answers
8 views
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, ...
0
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1answer
25 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 ...
0
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2answers
54 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 ...
1
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3answers
74 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 ...
0
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0answers
37 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 ...
2
votes
2answers
221 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 ...
0
votes
1answer
563 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 ...
3
votes
2answers
1k views
Why is symmetric NAT called “symmetric”?
After searching a while, I'm still not able to find a logical explanation on why is it called symmetric NAT.
Where lies the link between symmetric NAT and that each request is mapped to a unique ...
0
votes
2answers
111 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 ...
0
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1answer
84 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 ...
1
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2answers
93 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 ...
0
votes
1answer
84 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 ...
0
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2answers
43 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 ...
2
votes
1answer
37 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 ...
0
votes
1answer
41 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 ...
0
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2answers
61 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 ...
0
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0answers
209 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 ...
0
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0answers
15 views
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 ...
2
votes
0answers
82 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 ...
2
votes
1answer
71 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....
1
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2answers
34 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 ...
0
votes
2answers
66 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 ...
0
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2answers
62 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 ...
0
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0answers
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 ...
1
vote
1answer
45 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 ...
2
votes
0answers
33 views
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 ...
0
votes
0answers
120 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 ...
0
votes
3answers
187 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, ...
