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

3
votes
1answer
14 views

Source NAT on Juniper SRX300

I'm having issues setting up the Source NAT on my SRX300 firewall. The firewall is connected to an LC-panel through a fibre optic cable in port 0/6. I have set the public ip on that interface and have ...
2
votes
2answers
29 views

How could a response be sent to the requestor without requestor's address?

I'm reading this talking about the differences between two fire-and-forget message (for example, under UDP) and a request-response communication (for example, under TCP). I came across this: The ...
0
votes
1answer
26 views

Access internal webserver with domainname points to external IP

We have a webserver on our LAN. Externally, we can use the public domainname (let's say business.com) to access the website. Internally, we need to use the local IP. We also want to use the public ...
1
vote
1answer
27 views

How to run SIP phones in the LAN (NAT Overloaded to single IP)?

We have a small office network switch connected to a DSL modem for internet and telephony access. Now we would to extend network to another location in the same building for which I deployed a cisco ...
1
vote
1answer
35 views

Can VPN on router connected to the modem bypass a double NAT created by two routers unbridged and connected to each other?

I can't seem to get my head around this scenario. If I am right, a VPN configured on the client-side/workstation would definitely bypass double NAT but on this scenario: Modem <-bridged-> Router ...
-1
votes
0answers
33 views

IPsec with lan2lan redundancy

I need to establish IPsec tunnel between main office and remote office with lan2lan redundancy. Main Office - ASA 5515-x Remote Office - ASA 5516-x I have two ISPs, primary ISP gave me public IP ...
2
votes
0answers
36 views

Cisco - Change both source and destination on NAT [closed]

Note: As usual I'm dealing with single device so there are limits on what I can change outside of this router. Device: Cisco 1841 IOS: 12.4(13a) Vlan1 - IP: 192.168.0.3 Vlan1 (Default Gateway): 192....
7
votes
1answer
113 views

NAT VLANs with same IP Subnets

I have a VMware environment in which VMs are running a simulation suite. The software used has hardcoded IP addresses, about 10-15 VMs, and we are running multiple instances of this software each in ...
0
votes
0answers
29 views

ZyWALL 300 Port Forward Through Modem+Router Not Working

I have a Comcast business class router with a ZyWall 300 behind it. The network is in transition, but eventually the router in the modem will be turned off, however, we can't quite do that yet. The ...
55
votes
7answers
14k views

Why are IPv4 addresses running out?

I understand that we are running out (or ran out already?) of IPv4 addresses, but I don't really understand why that is. Right now, every home has its own IPv4 address (dynamically assigned, but still,...
0
votes
1answer
33 views

Cisco IOS 12.3 - Mysterious NAT - Where is it defined?

I have the following config (IOS 12.3): A.B.C.13 stands for the outside, public IP, bound on interface Fa0/1.52 37.247.X.206 is a public client I am using to test x.x.x.n stands for a random public ...
0
votes
1answer
28 views

Does the VM under the NAT network can contact the dedicated servers? [closed]

I have bellow snapshot's network configration: in the Dedicated Control Server(172.18.1.249) there is a VMware VM1 with ip 172.18.1.247, and it use the NAT network(gateway is 172.18.1.248). I want ...
1
vote
1answer
86 views

Port-forwarding rule on Cisco ASA not working - “Drop-reason: (acl-drop) Flow is denied by configured rule”

New to Cisco, so I hope this question isn't too noobish. I am trying to setup a port-forwarding rule to allow "any" SSL traffic in from "Outside" to the web server on my LAN. The problem is apparently ...
0
votes
1answer
64 views

ASDM access broken on Cisco ASA 5505 - NAT rule gone wrong

I was trying to setup NAT and Access Rules and apparently did something very wrong because now I cannot get into ASDM at all. I've tried multiple machines and all of them time out. Also the landing ...
0
votes
0answers
56 views

Redirect traffic destined to old server to an new server by ASA

There is a host that sends request to a server through a ASA (8.2) (in routed mode) the server's IP address is going to be changed the issue is that the new IP address cannot be changed on the host so ...
1
vote
1answer
44 views

Network ( routing and switching) , security

In my company network i am installing new cisco2811 router but i have problem, my LAN network can not ping and access network. i get point to point internet from ISP. PTP IP is 192.186.86.200/24 and ...
2
votes
1answer
50 views

Firewall Rule 'Both Ways'

I'd like to think I have a good understanding of NAT and Firewall rules at a basic level, though please correct me if I'm wrong at any point. I've seen many products list their firewall requirements ...
0
votes
1answer
55 views

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 ...
0
votes
0answers
69 views

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. ...
1
vote
0answers
47 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 ...
6
votes
2answers
181 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 ...
0
votes
1answer
30 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 ...
0
votes
0answers
66 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 "...
0
votes
2answers
69 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 ...
0
votes
0answers
49 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 ...
0
votes
1answer
22 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 ...
0
votes
2answers
78 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? ...
0
votes
0answers
30 views

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 ...
0
votes
2answers
55 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 ...
1
vote
3answers
91 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 ...
1
vote
2answers
325 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 ...
1
vote
2answers
96 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!
8
votes
2answers
660 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 ...
1
vote
1answer
254 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, ...
0
votes
1answer
24 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 ...
0
votes
2answers
46 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 ...
0
votes
1answer
27 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, ...
1
vote
1answer
54 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 have.Each IP on its own. Currently I have NatPool and it's working either with the one IP or with the other. Is ...
-6
votes
4answers
766 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?
1
vote
1answer
53 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 ...
0
votes
1answer
181 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 ...
2
votes
2answers
73 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 ...
2
votes
1answer
244 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
votes
1answer
82 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 ...
1
vote
1answer
62 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. ...
1
vote
1answer
155 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 ...
0
votes
0answers
142 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 ...
2
votes
0answers
98 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 ...
1
vote
1answer
39 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 ...
0
votes
4answers
114 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 ...