Questions tagged [nat]

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

Filter by
Sorted by
Tagged with
0 votes
0 answers
13 views

Sophos XG Virtual Host Load Balancing

I own a Sophos XG cluster (v18) and I need to balance http/https traffic at lvl 7, by virtual host, among different servers. To be clear: I need to balance the vhost www.example1.com between 2 servers ...
  • 361
0 votes
0 answers
32 views

How to NAT a unicast address to a broadcast address?

I have a 800-Series router connected in the following configuration: Port GigabitEthernet7 is connected to an external server (192.0.2.251) that sends unicast UDP to destinations 192.0.2.42:45100 and ...
1 vote
1 answer
67 views

Cisco ASA not accepting external traffic without NAT configuration

First of all, I am quite newie in the cisco world, so this could be some easy stuff that I'm missing. My first problem is trying to understand why a Cisco ASA5585 does not show traffic while doing a ...
  • 121
0 votes
1 answer
23 views

When a new entry in the NAT table is created and an entry in the NAT table is removed?

When using TCP, is a new entry in the NAT table created when a connection is made? and is an entry in the NAT table removed when a connection is closed? If I am correct, what happens if both ...
1 vote
1 answer
52 views

How can a port be both be used to identify a private IP, and also to connect to a specific service?

Sorry if im asking something nonsensical, im still trying to wrap my head around these terms. Heres my understanding NAT is the process of translating a private IP to a public IP, lets make an exaple ...
  • 13
0 votes
0 answers
14 views

Is Port Forwarding a type of NAT? [duplicate]

I am reading about Port Forwarding and NAT, these two concepts seem similar to me. Is Port Forwarding a type of NAT?
1 vote
1 answer
49 views

Site-to-Site VPN with BOTH sites behind NAT (mobile data routers)

I have 2 sites (call them "A" and "B") which connect to the Internet using 4G mobile data routers - don't knock them, I'm getting 200Mbps downlink and 30Mbps uplink, faster than a ...
  • 111
2 votes
1 answer
63 views

Do NAT Gateways Need to be the First Address of the Network?

NAT gateways are often given the first usable address in an address space. Do any protocol specs require this? Or is this just a convention? I skimmed RFC 1918 and RFC 2663 but didn't see anything ...
0 votes
2 answers
69 views

How does NATing work

I'm not 100% understanding how NATing works. Let me setup our network and talk this through. So first of all, lets say that I have an IP size of 4 bits so 16 possible combination. The only private ...
1 vote
0 answers
60 views

Full Cone NAT on Cisco router in Packet Tracer

I am trying to create a network with two subnetworks with private IPs. I need to configure symmetric NAT on edge routers within the subnetwork. Diagram: I need to configure NAT on Router0 and Router2....
  • 11
0 votes
1 answer
42 views

Is it possible to send network messages with "Fake" Local Network(192.168.x.x) destination IP but actually reaches the destination via internet?

I am configuring a MySQL server that is only intended for computers from internal network/local network machines to access. Now MySQL has a "bind IP address" setting that, if I set it to the ...
  • 103
0 votes
1 answer
66 views

Cisco ASA VPN tunnel shows up (phase 1 and 2, MM_ACTIVE), but no traffic passes

My end of the tunnel is on an ASAv in AWS. (version 9.14) show crypto isakmp sa 4 IKE Peer: 212.239.x.y Type : L2L Role : responder Rekey : no State : ...
0 votes
0 answers
15 views

How are we still able to use IPv4 address even with NAT? [duplicate]

My question is why haven't we run out of IPv4 public IP as well because now almost all home has a router which is assigned a public IP. Is it possible to have multiple layers of NAT on the router-ISP ...
0 votes
1 answer
23 views

Why are External NAT ports different when both NATs are restricted cone? [duplicate]

I'm in the progress of implementing my own Signaling server with UDP hole punching, everything have been smooth up until both hosts were behind Restricted Cone NAT, then the ports for P2P ...
  • 1
1 vote
1 answer
147 views

Checkpoint Firewall using wrong Source IP when establishing a VPN

I have a checkpoint VSX environment running r81 and I have a DMZ firewall that has two external interfaces. One that goes to the Internet and one that goes to a 10.0.0.0/8 network that connects to ...
0 votes
3 answers
75 views

why ip adresses are divided into network portion and host portion when we already have NAT [duplicate]

I don't understand why ip adresses are divided into network portion and host portion? is the host portion really necessary when we already have NAT? for example, if ip addresses only have network ...
2 votes
1 answer
78 views

Trying To connect Router4 to internet

In the picture, I have a part of my topology. The concept is that I am trying to configure OSPF in my network. Internet is a nat cloud module. The routers are all iosv routers. ISP 1 has the following ...
  • 89
3 votes
2 answers
723 views

Configure NAT in Vyos Router

I have the following diagram, and I want that R2 and each client connected with R2 have access to the internet. For that I configured NAT in R1 with the following commands: #set nat source rule 10 ...
's user avatar
0 votes
3 answers
144 views

How NAT router use layer4 contents in layer3?

I followed from this question and @PeterGreen's Answer , and come to know that NAT router working in layer3, but using layer4 contents(layer4 port number,layer4 checksum). My question is when layer3 ...
0 votes
0 answers
4 views

Source Port NAT with VPN [duplicate]

I understand that a router (like an home router) does source port NAT (as the public IP for a LAN is normally one). If I run a VPN Client (like Open VPN) on a computer in the LAN and if the VPN packet ...
  • 101
0 votes
2 answers
37 views

Does Port Forwarding limit ports available to NAPT?

I'm wondering if routers limit the possible ports available to NAPT when port forwarding is configured. For example, given one public IP address all but two ports assigned via port forwarding, would ...
  • 3
0 votes
1 answer
50 views

Switching Internet connection on Cisco ASA

I use Cisco ASA in branches of our organization. Each device has an IPsec tunnel that connects to the main office. To access the global network each device also has a NAT. Recently, a task arose to ...
  • 155
0 votes
1 answer
41 views

Error cluster with packets balacing through NAT

Im trying to make a web cluster (HTTP and FTP) with 3 linux machines where the packets are balanced through NAT and im using Bridge interfaces and HSRP, because im using 2 routers(using c3660 image) ...
0 votes
2 answers
107 views

What is the use of SNAT (Static Network Address Translation)?

If SNAT is used to map internal private IP addresses directly to a non-changing public IP address, why not simply assign the public IP addresses directly to each host itself? What advantage dose SNAT ...
0 votes
1 answer
284 views

Why or when do we need Layer 2 NAT? [closed]

What is the point of public addresses in Layer 2? Why or when do we need it? When is it healthy to use? Or is it even a common thing? Sorry I am kinda new at networking and I just googled it but ...
1 vote
2 answers
79 views

How can I use scapy to make a port appear open-device behind NAT?

This has been asked in stack overflow like 7 years back. I don't see the correct answer there. Is there any way to do this? While this packet keeps on being transmitting, doesn't the other end see the ...
1 vote
1 answer
71 views

NAT in ASA (5505) Firewall is not working for VLANs configured in Layer3 Switch?

Toplogy: Tool Used: Cisco Packet Tracer Scenario: NAT for hosts in any of the VLANs of Layer3-Switch not working. Ping requests reaches outside server, but NAT is not working so ISP Router can't ...
  • 121
0 votes
1 answer
455 views

How to configure NAT in Cisco ASA Firewall for all VLANs connected to layer 3 switch? [closed]

Topology: How to set up NAT in Cisco ASA Firewall (in Packet Tracer), when there are VLANs in the network? In the current approach, NAT is not working to reach the server (8.8.8.8) from any of the ...
  • 121
0 votes
1 answer
99 views

Cisco 2851 Static NAT Entry - Similar Static Entry Already Exists

Thank you in advance. I have a few 2851 Cisco ISR. This is my NAT Pool config; ip nat pool NAT-Pool 38.xxx.xxx.193 38.xxx.xxx.206 prefix-length 28 ip nat inside source list 1 pool NAT-Pool overload ...
1 vote
1 answer
57 views

What's the procedure to limit a subnet on a Cisco router from seeing another subnet when both are using NAT?

I have a Cisco 891F router. The internet is hooked up to G8. The student network is Vlan 200, and the Office is Vlan 100. (I know the internet has an internal subnet (192.168.1.5), but that's because ...
  • 13
2 votes
1 answer
123 views

NAT not working in cisco packet tracer

Cisco Router Version: 16.7(3r) Cisco Packet Tracer:8.0 x64 Router(config)#interface dialer 1 Router(config-if)#ip nat? % Unrecognized command Router(config-if)#ip nat ? % Unrecognized command Router(...
  • 23
1 vote
1 answer
39 views

Linux: address the same IP range (different networks) via two interfaces masqueraded [closed]

Not sure whether it can be done: Due to a legacy setup there are two separate networks that both use the same class C subnet 192.168.0.0/24. I have a Linux box with two physical interfaces wherein ...
0 votes
1 answer
41 views

Are NAT external:internal mapping types the same for UDP and TCP

Suppose I use a STUN server (UDP) to determine that a client's NAT randomly assigns external port values. Does this imply that the client's NAT will also assign random external port values when using ...
1 vote
1 answer
472 views

How to perform an inbound and outbound NAT at the same time in Pfsense?

I have a rule on a stormshield performing NAT on both the source and the destination address. It is done very simply in one rule. Example : --Before translation-- --After ...
  • 11
2 votes
3 answers
893 views

Private IP address vs Local IP address

Say a router is connected to two devices. Now the router will give those two devices different private IP addresses. The router itself has a private IP address (which serves as the default gateway for ...
  • 123
4 votes
3 answers
368 views

Questions about NAT

So i just started learning about NAT and networking in general. As powerful as this technology may seem, it was specifically made for reducing the amount of IPV4 addresses used throughout the internet,...
  • 43
1 vote
1 answer
138 views

Cisco ASA nat from inside to outside, but network that is routed to inside interface

So is it possible to nat from inside to outside interface but not the inside ip subnet, rather the ip subnet that is routed to inside interface? #object network remote_ip_subnet #subnet 192.168.1.0 ...
  • 812
0 votes
1 answer
149 views

How does NAT modify the headers correctly?

How does the process of replacing the incoming message (say from stackexchange) to the router, and modifying the header with my PC IP happen? How does the router know which IP to insert there? Is ...
  • 105
0 votes
1 answer
112 views

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 ...
0 votes
1 answer
51 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.
0 votes
1 answer
65 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 ...
0 votes
2 answers
878 views

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 ...
0 votes
0 answers
97 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 ...
  • 1,660
0 votes
2 answers
56 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 ...
0 votes
0 answers
29 views

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 ...
0 votes
1 answer
23 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 ...
  • 101
1 vote
2 answers
324 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 ...
0 votes
2 answers
61 views

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 ...
0 votes
2 answers
152 views

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 ...
  • 103
0 votes
3 answers
127 views

PIM Packet and NAT

Is it possible to NAT PIM Join packet? Assume the receiver and the source are in two different networks (address regimes). Thus NAT is required. The upstream source and the groupe are included in the ...
  • 107

1
2 3 4 5
13