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

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Is an SBC sufficient and can it NAT

We have a gateway which faces out to our VoIP SP. As we get more users we need some security in front of it. Currently our gateway terminates directly to the SP. We would like to put a SBC in front ...
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Will Cisco ASA static NAT on hairpin/U-turn on outside interface affect SSH access from outside interface?

Thanks for taking the time to look at this question. Presently, I have a Cisco ASA 5505 (8.2.x) with public IP address A.A.A.A. The only configured interface is the outside interface of the device. ...
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12 views

How to route all the traffic from wlan0 to eth0 and making ip given to wlan0 act as a gateway? [closed]

I have 2 laptops both connected on the same LAN using wifi. In One laptop I have a working internet connection which I shared to laptop 2 using Ethernet, as I wanted to create a new gateway on the ...
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18 views

pfsense Server Load-balancing on LAN Interface

I am trying to load balance a couple of web servers from the LAN side as I don't need access from the WAN so that clients on the LAN can access these web servers: LAN IP is 192.168.10.1 I created a ...
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2answers
88 views

How does NAT work with incoming UDP packets from unknown IP

Apologies in advance for the relatively noob question and if this is off topic here ( I am not sure...) The situation is that I have a UDP client and server bound to the same port. My understanding ...
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12 views

Outbound NAT for single host behind an ASA located over an IPSEC tunnel

I have these two nets connected over the public internet with ASA 5510s. 192.168.0.0 < -- ASA1 ---> Internet <--- ASA2 --> 192.168.5.0 Each net does either a simple dynamic or static nat ...
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31 views

what is a reverse nat and why would i need it? [duplicate]

Though I could find some definitions of reverse NAT (like from here), I couldn't really understand why it is needed. I'd really appreciate some examples. And please don't get confused with the "...
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2answers
39 views

Leak default route to multiple VRFs while keeping VRFs isolated from each other

I'm working on a configuring stuff on a Cisco Nexus 3k based platform and trying to isolate different things into different VRFs which should not be able to talk to each other. Some of these VRFs ...
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33 views

Cisco ASA 5506-X create a NAT rule via GUI/cmdline

Hi the Stack Community ! I have some problems with creating a NAT rule with that Cisco device, (of course you already undestand that I m a beginner with Cisco devices ^^) The configuration schema ...
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1answer
20 views

Connect office to multiple customer VPNs

First time post here so if this is off topic please let me know where to ask this question. A company that provides outsource billing services to multiple client companies using VPNs to each remote ...
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2answers
69 views

Why does NAT keep track of each packet not just connections?

I have tried packet tracer and actual cisco routers and I find this weird: NAT uses different source ports, usually incrementally, for consecutive packets from the same connection. Why is that? ...
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How do I get Inter VLAN Routing going with HPE MSR2003 Router and a Cisco Managed Switch (generic type)

thanks in advance for your time and effort. I recently bought / acquired via obsoleteness a set of networking hardware which I want to extend my home lab with. The HPE MSR2003 should function as a ...
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2answers
42 views

How does the NAT work [closed]

I have a public ip assigned by isp, two phones are connect to wifi router. In both the phones i am seeing news feed on different facebook accounts, so facebook gets packets from only one publuc ip ...
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3answers
81 views

Why can't a host B act as a server, and accept TCP connections, when sitting behind a NAT?

Originally, I thought I intuitively understood why B can't accept TCP connections, however when I read about how P2P applications circumvent this exact problem by using an intermediate peer that is ...
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2answers
86 views

Why to use public IP addresses within private networks?

I have started to work in a multinational company which has a global network spanning across 4 continents (20 0000+ network devices). I noticed that a lot of end user devices (PCs, laptops) have IP ...
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2answers
85 views

What is the point of outside NAT?

I understand how outside NAT works, but I do not know when it should be implemented? Could you please tell me some scenarios when outside NAT is needed? Thanks!
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2answers
611 views

routing between vlans not working

I need to put a Cisco router behind an ISP router. (The ISP doesn't allow us to use their modem only.) I've called the ISP technical service and they've set up the connection with me. Their router ...
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1answer
104 views

Configuring the NAT 1:1 rules with pfsense

I have two pfsense. One pfsense is on 192.168.0.1 and another pfsense is on 192.168.20.1. Basically I have installed 20.1 pfsense on one machine 192.168.0.180 which is in the network of 0.1 pfsense, ...
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1answer
23 views

Why specify additional NAT rule

In watchguard's guide for NAT loopback when describing the additional nat rules required, they show this image: Why are those top two NAT rules necessary, ie aren't they already covered by the next ...
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2answers
40 views

IPSec - NAT-T inner/outer IP of the gateway?

I was configuring an IPSec VPN and somehow I can't figure out what the inner/outer IP of my gateway would be. Have a look at this image : Imagine I have my site-to-site VPN, with my gateway having ...
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1answer
26 views

Discovering public ip from wifi signals, shodan, parent router NAT [closed]

MAC addresses innately do not change right? and you're able to scan for broadcasting APs where you'll be able to detect different nearby mac addresses of each AP.. Public IP addresses change, ...
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1answer
47 views

Asa5508 NAT two internal IPs

Hello i have a Cisco asa5508 and i want to nat 2 internal ip's to 2 public ip's that i got.Each ip on its own, Currently i got NatPool and its working ether with the one ip ether with the other . Is ...
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4answers
156 views

What is the difference between DHCP and NAT?

Both seem the same to me. I don't see how DHCP is different from Dynamic NAT. Can anyone please help?
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1answer
41 views

2 Wan DHCP to cisco router

I have a cisco 2921 router and 2 wan ips provide by 2 diferents isp via dhcp. The main connection is funtional right now, I have a subnet with a nat to this ip, but I want put the second ip just to ...
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1answer
99 views

ASA VPN Tunnel NAT Issues

I've been trying to jump through two tunnel. A Customer has a cloud solution which we need access to. Since we already have a vpn site2site tunnel to the customer we can already access his LAN. What ...
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2answers
68 views

How does/did an ISP serve so many people over IPv4

Whilst reading Tanenbaum - Computer Networks they talk about IP scarcity at the level of ISPs: IP addresses are scarce. An ISP might have a /16 address, giving it 65,534 usable host numbers. If it ...
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1answer
136 views

At which layer does router operate?

I have studied from various sources that router is a layer 3 device. It does routing based on Network layer (layer 3) header, but I have a doubt. Network address translation (NAT) is a feature of ...
3
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1answer
77 views

Can a host behind a basic NAT visit two services on a server at the same time?

When reading Data Communications and Network (5th edition) by Behrouz A. Forouzan, I have trouble with the explanation for NAT. On page 546, the book describes a modifying-IP-only NAT (a.k.a. basic ...
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1answer
56 views

HP MSR2004 router is not processing udp through nat

I set up a new HP MSR2004 router for a corporate network. The network uses an internal private net and has one static public ip address. Surfing the web and all tcp related things seem to work fine. ...
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1answer
92 views

Bridging networks without NAT: how it's done?

I have quite limited networking experience, so probably i'm asking about very simple things. I'm reading about linux bridge interfaces, and documentation states that there is no NAT by default and ...
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0answers
107 views

Slow performance with Cisco Comcast Business router with static IP address

20I have a server with a static IP address connected to a Comcast Business router (Cisco DPC3941B). I also have a second machine directly connected to the same router. It gets assigned a NAT address ...
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0answers
96 views

Cisco: Routing issue between LANs [closed]

We have a project to create 3 offices, which are 3 different LANs where the configuration should be as follows: Each Office should have 1 printer, where the office is able to print They should be ...
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1answer
29 views

Is an ACL needed when using PAT (dynamic nat)?

We have a single router (4331) that connects to our ISP. We do PAT (dynamic nat) to give users internet access. Now typically we'd have an OUTSIDE-IN ACL that blocks traffic from the internet. My ...
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4answers
109 views

How does the router tell if a packet is sent to local host or public host

I might sound silly, but I'm beginner. If there are two hosts with the same IP but one is public and the other is private. If I send a packet to that IP. Will it be forwarded to the local host on my ...
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1answer
48 views

IPv6 VPNs source address selection

Say I have the following IPv6 prefix assigned to me by my ISP : 2a01:1000:1000::/48 with 2a01:1000:1000::1/48 assigned to my VPN server. I set up a VPN with a /64 from that block to assign to my ...
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1answer
106 views

How is CIDR Used Today with the Introduction of NAT?

I'm new to networking and trying to understand how CIDR is still relevant with the introduction of NAT. If we have a public/private scheme for routers, how is CIDR still relevant? Is this at an ISP ...
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2answers
95 views

What provision does DS-Lite, as used by ISPs, have to provide IPv4 blocks to CPE?

I run a small ISP for a rural community in England. There are around 350 residential properties and 15 small businesses. Three of these businesses run systems that require two consecutive IPv4 ...
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1answer
50 views

Configuring Cisco ISR 1861 with External Cable Modem

I picked up an 1861 for cheap and I am trying to set it up for home lab. I have taken the Cisco courses for CCNP and I think if this was just a regular router or switch I would be OK, but I can't ...
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3answers
138 views

Translate between multicast addresses

I have an application with a bug that does not recognize a certain multicast address as valid. It's an address used by another system i don't have control over, and these two systems communicate via ...
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2answers
260 views

How do ISPs configure a static ip in a double nat? [closed]

So I have an ISP which I requested a static ip. My ISP gives a static ip for a one time payment. So I decided to get one. My ISP does double NAT which by default all incoming tcp ports are blocked. ...
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1answer
80 views

Accessing Servers behind double NAT [closed]

Basically, I want to know every possible way to access Linux servers or any other devices located behind ISP'S (Carrier-grade NAT) and our local NAT. I have used VPN and forward-reverse tunneling ...
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2answers
173 views

ASA cannot ping outside through NAT on border router

I have the following topology below, in GNS3. Basically, the cloud NAT-1 is the Internet, R1 is my border router with NAT and FWASAv-1 was supposed to be able to access the Internet, but can't. I ...
5
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1answer
469 views

How does UDP NAT Know When To Remove The Rule

So say you are a user behind a NAT/router on an internal network. You begin sending UDP data to an internet-facing server. The packet hits your router, it inserts an entry to allow returning packets ...
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1answer
118 views

Should DHCP relay and destination NAT work together?

Topology: [PC1]---lan----[RT1 / DHCP relay / DNAT]---wan---[DHCP server] [PC2]---------/ / [PC3]----------/ DHCP relay makes the a DHCP broadcast into a unicast and Forwards it to the DHCP server ...
4
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1answer
110 views

What Is Session Border Controller [closed]

What is Session Border Controller(SBC). And What is the Advantages of SBC. How Does It Works?
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3answers
2k views

How does NAT decide which connections are inbound, and which are outbound?

I'm building a P2P application that needs to be able to access nodes behind a NAT. This NAT does not allow inbound connections, therefore the nodes outside the network cannot reach out to the nodes ...
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1answer
1k views

How does NAT Stitching work?

While reading about CISCO NetFlow Analysis I came up with a term named NAT Stitching. I understand Flow Stitching which join same type of inbound and outbound connection. But can't find anything ...
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1answer
82 views

Translation from unique local to global unicast address

is there NAT in IPv6 for private-to-public translation like in IPv4. I know that there is a protocol translation between v4 and v6 but did not find anything about same protocol translation . Thank ...
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1answer
231 views

1-1 NAT on a SonicWall with a DMZ

A new PBX is being installed at one of our clients today, and they have requested that we give them one of our unused public IP addresses(Comcast is the ISP, have a block of IPs) for use with the PBX. ...
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2answers
124 views

How does NAT table response when there are no open ports?

I'll be glad to hear what really happens if the router has no open ports, for example if there is a big network and every computer sent a lot of requests and the server is slow so the table's ports ...