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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CGNAT port allocation

I'm planning to implement CGNAT in service provider with a10 networks. So, the question is how many private IP addresses I can NAT through one public IP ? One public IP = 64511 ports = 400 ports per ...
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23 views

Multiple VLANs with PAT

I'd like to know if it's acceptable/possible to use PAT with multiple VLANs, by using the same translated IP address for all VLANs.
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30 views

Is this a good network configuration?

I am trying to configure ip sla for non directed link . I have configured static route to reach to non directed link 1 configured track 2 configured ip sla 3 configured access-list 4 configured NAT 5 ...
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can someone explain the tracert result on my own public IP [closed]

I'm trying to learn about ip routing and I'm am trying to trace route my own public IP. I just searched my ip online and tried it. the results I got were > tracert [my_public_ip] 1 <1ms 192....
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Connect to SQL Server using Public IP [closed]

I try to connect to a remote database over the internet, usually the way I connect is by getting my public ip and adding it to the firewall. But now that I try to obtain my public IP on pages like ...
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Palo Alto Firewall: Why is double NAT needed?

The diagram shows my current network configuration. (Where X is 10). I have the firewall interface E1/2 at the left configured to 192.168.10.1/24. It is in a trusted security zone. A DHCP server is ...
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9 views

Configure port forwarding with interface command within VRF

We are working with VRFs and having a look into the NVI NAT configuration. Without VRFs, we can configure following: ip nat source static tcp 10.0.0.2 80 interface Dialer1 80 ip nat source static tcp ...
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2answers
42 views

NAT Unable to Translate on Packet Return

I am currently working with the network above. When ever I send a packet across from a network, on the return to the router it is unable to translate back and ends up dropping the packet. I am how ...
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Why Does Symmetric NAT imply a TURN Server? [duplicate]

I am using ICE/STUN in the context of WEBRTC. I understand why STUN does not work with symmetric NAT. The answer to that question is here: why STUN doesn't work with symmetric NAT? I am asking a ...
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1answer
11 views

Allow only specified set of IPs to use external port on pfSense

I have a pfsense router and a NAT rule that allows a port redirect. | GitHub | - ( Internet ) - [pfsense] -net port translation- [ Jenkins ] I want gitHub to be able to reach my jenkins, but no other ...
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2answers
73 views

Why do we need private IP address range?

When it comes to local networks, you have the freedom to use any IP address you want for your network since it doesn't need to communicate on the internet with other devices. However, the RFC ...
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Help understanding NAT/PAT - With example

Would anyone be able to clarify what ive been thinking is correct or if this is a complete misunderstanding and possibly answer these questions if you have time? So I understand that NAT/PAT is giving ...
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2answers
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Concurrent site-to-site VPN tunnels through dual ISPs (with 2 couples of Cisco ASA) between same devices

I currently have a simple site-to-site VPN setup, connecting machines from site 1 to site 2 through 1 ISP, using a set of ASA 5506X. All is good. I'd like to "double" that setup for ...
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PIM Packet and NAT

Is it possible to NAT PIM Join packet? Assume the receiver and the source are in two different private network. Thus NAT is required. The upstream source and the groupe are included in the PIM Join ...
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1answer
105 views

Can a server on the other end of a site-to-site vpn be exposed (NATd) to a public IP on an ASA

AWS DataCenter ----------- site-to-site VPN ------------ http server <=======================> Cisco ASA public address 10.0.1.59:443 ...
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37 views

IP masquerading and nat

what is the difference between IP masquerading and nat? do both of them have the same limitation? in the line "IP masquerading cannot provide full internet connections to the hosts which hide ...
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Configure nat on src ip to dst port

I wondering about some workaround for issue that I have: I have 2 sources which generates multicast to 224.1.1.1 and port 12345. I'd like to configure on my Cisco IE 3000 NAT which will change the ...
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How does 2 computers both behind NAT routers handle communication? [duplicate]

Currently reading up on TCP/IP protocol stack, while I was reading about the Network Interface layers, I started reading about NAT, and how it meant to decrease the amount of IPv4 used, by using the ...
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1answer
71 views

Cisco IPsec VPN tunnel problem

I have a problem with VPN configuration. This is the topology I created: First updated licenses to make the VPN available: license boot module c1900 technology-package securityk9 IPsec Router ...
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1answer
211 views

Cisco, Router can communicate; hosts cannot

I am learning CCNA related tasks, I have picked up a Cisco 1900 Series router. I am attempting to set it up behind my existing router (Comcast standard router). My "Real" network is 10.0.0.0/...
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1answer
51 views

NAT cannot communicate with 2 network

I have configured BGP for routing and NAT for HQ and Branch. I can ping from windows / server to public IP and also Linux Mint ping to public IP. but, I cannot ping / communicate between network HQ to ...
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46 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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3answers
100 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 ...
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2answers
64 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 ...
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3answers
87 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 ...
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1answer
43 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 ...
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95 views

Why cant't IPSec's Transport Mode ESP 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 ...
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1answer
26 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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290 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 ...
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1answer
76 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 ...
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1answer
38 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 ...
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2answers
92 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 ...
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53 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 ...
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2answers
59 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 ...
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1answer
198 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 | ...
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4answers
101 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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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 ...
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1answer
813 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, ...
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2answers
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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 ...
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1answer
262 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 ...
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2answers
46 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 ...
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9 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, ...
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1answer
27 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
56 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
102 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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0answers
47 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
720 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
935 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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2answers
4k 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 ...
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2answers
179 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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