Tagged Questions

In computer networking, network address translation (NAT) is the process of modifying network address information in datagram (IP) packet headers while in transit across a traffic routing device for the purpose of remapping one IP address space into another.

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11 views

SFTP Reverse-Proxy using iptables on custom port

I want to give SFTP access to anyone into to my Server (IP: ss.ss.ss.ss) passing through Proxy (reverse-Proxy? IP: pp.pp.pp.pp), so that IP ss.ss.ss.ss is never seen by whoever is connecting to the ...
-4
votes
1answer
37 views

Can I use an external IP to make 2 internal IP's establish a TCP/UDP connection? [on hold]

As I understood, in order to make a connection to an internal IP (behind NAT), the computer behind the internal IP have to send the request first before the other side will be able to answer it, So if ...
0
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0answers
30 views

iptables - dropping specific established connections after X hours

Is there a way with iptables to drop specific established connections after X hours? We have an application with limited connection support, and occasionally we see some tcp sessions that shouldn't ...
0
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0answers
17 views

rdr on local (originated from the machine) traffic on OSX Yosemite [on hold]

I am trying to proxy 22 traffic, originated from my machine, so it will be proxied / forwarded to a remote server. This was very easy with ipfw but Yosemite has only pf .... Did anyone found out how ...
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0answers
16 views

Ubuntu can't connect as IPSec L2TP client

Goog afternoon, I have a corporate local network located behind NAT. There is another NAT in this local network for the corprorate server on Ubunit 12.04. So if clients connect to that server ...
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2answers
59 views

Is it a security improvement to use NATed network?

There is a website that blocked an ISP's subnet (because attacks came from that network). The ISP gives it's users only NAT'ed IP addresses, so the clients are geting 10.x.x.x IP addresses on their ...
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1answer
39 views

How to start with IPv6 subnetting on linux gateway

We are currently having perfectly working IPv4 network with a typical layout - internal network with all servers splitted to VLANs in 10.0.0.0/8 (each vlan is /24) and external network with public ip ...
0
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1answer
63 views

How to trace dropped TCP connections?

Trying to help someone with a situation where TCP connections get mysteriously dropped after a few minutes for no apparent reason (this happens even with non idle connections). Both client and server ...
0
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1answer
36 views

Proxmox VE: Multiple shared public IPs with NAT configuration

I have a Proxmox VE (v3.3 @ Debian 7 Wheezy) and got 3 public IPs routed to that server. It is my aim to have multiple VMs sharing those IPs using a NAT configuration so that I can forward single ...
0
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2answers
68 views

Forwarding HTTPs requests to another webserver

I have an Ubuntu 12.04 Server connected to two subnets. Eth0 is 20.20.20.1, it hosts an Apache Web Server on port 80. Eth1 is dynamic IP address in 10.10.10.0 subnet. This server is not a gateway ...
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votes
1answer
37 views

Can't set up the default route from a sublan to the WAN [closed]

I am trying to connect one of my PCs to the Internet via a WiFi network using a notebook. Here is my network : (Wifi) <=============> (Notebook) <===============> (Desktop) ...
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1answer
26 views

iptables with sticky forwarding/routing

My iptables is sticking. I have a DNS server behind IPTables and down a NAT'ed OpenVPN pipe. Using tcpdump I see DNS packets hit the outside router but it takes 4 or 5 DNS query attempts before the ...
0
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1answer
36 views

Keep source port for outgoing packets

I have 2 interfaces eth0(192.168.0.1) and eth1(10.1.1.15). And I do nat for all packets in this way. iptables -t nat -A POSTROUTING -s 192.168.0.0/24 -j MASQUERADE Now I want to keep source port ...
0
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0answers
27 views

Does NAT forwards ping requests and port scans to all subnet computers? [migrated]

If I ping some friend's public IP address, this is usually the address of his router. Does the router forward the ping request to all devices on it's network? If the devices are all turned off will ...
0
votes
1answer
28 views

Proxmox with iptables nat is not available

I got an issue with iptables on my virtual machines. I installed proxmox 3.1-21 on my rootserver. I have around 6 IPs linked to my rootserver so i created new 'CT's. The problem is i need to ...
-1
votes
0answers
25 views

Network issue if RRAS NAT enabled

I have a newly installed Windows 2012 R2 on my server. I want to enable NAT to handle the routing for the clients and the virtual machines what are running on it. I added the necessary roles for it ...
0
votes
0answers
26 views

Debian forward through NAT EOIP GRE

eth0 = WAN eth1 = LAN to forward any port through nat I use e.g: iptables -t nat -A PREROUTING -p tcp -d 79.188.31.34 --dport 8291 -j DNAT --to-destination 192.168.0.36:8291 and it works, but ...
0
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0answers
71 views

Linux router with multiple gateways and port forwarding

I want to use a Linux VM to act as several routers at once. I have multiple servers hosting different services and dedicated public IP for each of them. Super simplified setup example: Ubuntu ...
0
votes
0answers
4 views

Conntrack gets incorrect forwarding rules for outgoing protocol 41 [migrated]

I'm trying to forward protocol 41 (ipv6-in-ipv4) for an HE tunnel through a WRT54G running Tomato 1.28. Tomato 1.28 is running a 2.4 kernel that knows absolutely nothing about protocol 41, except that ...
2
votes
0answers
91 views

Apache Instance in Private Subnet not returning packets

How can we get the Apache instance in a private subnet to work? Configuration Public subnet with 1 NAT instance Private subnet with 1 App instance Details 1. Masquerading is turned on NAT on via ...
-1
votes
0answers
28 views

How does NAT handle multiple computers contacting the same external IP at the same time? [duplicate]

As I understand it, NAT allows multiple computers to share the same external IP address. It does this by waiting for a computer behind the NAT to initiate a request to some external server, then ...
0
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0answers
28 views

Should a NAT host be separate from a Bastion host

Have a private network with servers that required SSH access. Since the instances are in a private subnet, they cannot be accessed directly via SSH and require a public Bastion host to access. ...
0
votes
2answers
91 views

Using Router with DHCP and NAT and Windows Server 2012 as DNS

I have a network currently set up as per the image below. We use Regus's shared Internet and I've create a sub network for our office by using DHCP and NAT on the airport extreme router. Now the ...
0
votes
1answer
62 views

Port forwarding with iptables -> connection refused

I am trying to redirect requests to my local IP (10.42.42.152) on port 80 to a remote server, e.g. google.com (173.194.113.104:80). The remote server is up, ip_forward is enabled but I only get ...
2
votes
1answer
52 views

Stateless NAT with CentOS 6

I'm looking to set up the following: ---[IVR 1] | (internet)----[CentOS box]---+---[IVR 2] | ...
0
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0answers
23 views

tun0 not listening traffic on a simple vpn example

I tried to setup a simple vpn test server on Ubuntu 12.04, called ToyVPNServer. The guide is simple and I take test for days but still cannot get connected. The inspection result is showing the issue ...
0
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0answers
16 views

SRP521W Intervlan routing and NAT

I've a Cisco SRP521W router which I've set up with two VLANs called normal_Lan and SWSVLAN. I don't want devices on each VLAN to communicate with each other so I've turned INTERVLAN Routing OFF. ...
0
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0answers
35 views

Cisco 2901 Inbound NAT with local IP overload

Overview We are replacing a Juniper SSG on one of our networks with a Cisco 2901. Everything has so far been quite smooth except some issues have come up with external ports needing to be opened. ...
0
votes
0answers
72 views

Remote client (android) can't connect to OpenVPN sever behind LAN

My plan is to connect over tunnel (via Internet) android phone with my LAN at home. I set up OpenVPN server behind (router) lan (ip adress is 192.168.1.3). There is also my laptop. Port 1194 UDP on my ...
0
votes
0answers
31 views

NAT with port forwarding on same interface

I have some issues with the port forwarding on same interface. I have server1 with the public IP 5.1.1.1 and one company publish a MySQL database with IP 10.1.1.1 through VPN reached only by server1. ...
0
votes
0answers
27 views

How to use linux repository for setup (ubuntu) when box are in aws scenario 2 wizard created private subnet?

I know lots of questions and I have personally tried manual VPC creation multiple times until I gave to the wizard (NAT concept wouldn't stick). I thought the wizard would actually configure ...
0
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0answers
32 views

NAT Traffic via my instance in Microsoft Azure

I'm working in Azure IaaS Environment I have a private network 172.16.0.0/16 in which I have few linux instances running (172.16.0.1-5) My instances are accessing the public internet on port 80 (so my ...
-3
votes
1answer
33 views

What happens if all the ports of router(doing NAT) are occupied ? [closed]

Suppose n computer are connected to a router R .It is doing NAT but suddenly all of its ports are occupied .So when a new computer N tries to connect what would router do means it simple do not ...
0
votes
2answers
43 views

Connecting to OpenVZ Container that uses NAT

lets say i do not have enough IPs to allocate to each container, how would someone connect that container if it has no public address? (using NAT for that container) the address would be private ...
1
vote
1answer
29 views

It it safe to forward an ephemeral port to an internal host in a NAT environment?

Short story, I want to expose SSH from a box in a NATed environment to the internet but would prefer to do it on a high (in the ephemeral range) port. Is it safe to port forward an ephemeral port to ...
1
vote
1answer
181 views

Is it possible to configure a reverse VPN tunnel?

Basically, my goal is to have a 100% portable and independent server. I'm building it using a Raspberry Pi powered by solar panels and batteries, and it is to be connected to the internet using a 4g ...
0
votes
1answer
50 views

Port forwarding with 2 interfaces not working

I'm running debian and I've got the following network configuration: eth0 Link encap:Ethernet inet addr:192.168.16.6 Bcast:192.168.16.255 Mask:255.255.255.0 inet6 addr: ...
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0answers
93 views

Cannot Access web Interface https Zimbra from WAN

I have a zimbra 8 installed on Ubuntu 12.04 LTS I can access to web interface (https) from LAN. I just type https://192.168.1.10/ in the Firefox. But if i try to access from other PC to my WAN IP ...
0
votes
1answer
43 views

IPsec VPN Site-to-Site: Unable to reach hosts on same subnet as gateway

I am trying to bridge an office network with an Amazon VPC cloud network. So far everything seems to be working, except that I cannot reach servers on the same subnet as the cloud gateway. Office ...
0
votes
2answers
51 views

use iptables's nat to proxy mysql

I find this similar thread but don't work: http://stackoverflow.com/questions/10864854/forwarding-mysql-connection-with-iptables-and-differents-network-interfaces?rq=1 My environment as follows: ...
0
votes
2answers
84 views

NAT Masquerade to a L2TP/IPSec connection

I'm trying to create two networks (using a debian server) : The first one is intended to pass packets in a normal way (to my ISP). The second one is intended to pass packets via a L2TP/IPSec VPN ...
0
votes
0answers
64 views

How can I allow NAT from inside to outside and vise-versa when each of my clients will have only one static public IP using an ASA5525-X?

My network topology is pretty basic. My data center provides a router and added a switch just before my cage to provide connectivity to all of the racks. My rack takes the copper drop they provide and ...
-1
votes
1answer
24 views

Need help configuring NAT

First of all, the router I am using is a Cisco WRVS4400N. My company runs a software which handles the MySQL database of all of their products. The software now has an e-commerce module, so I have ...
0
votes
0answers
20 views

Cisco ASA5505 Public IP Address

I am trying to configure a Cisco ASA5505. I am using the GUI start up wizard. When I assign the outside IP address to be a public IP address the configuration will work but after about 30 seconds the ...
0
votes
1answer
22 views

Iptables and counters

I'm trying to use iptables counters with munin to monitor traffic of hosts on my local subnet. For each host I set up a rule like this: iptables -I OUTPUT -d $ip This should count the packets going ...
0
votes
1answer
51 views

Configure clients to navigate through specific wan. Pfsense

I have a machine with a pfsense running. It is configured with three ethernet cards. LAN 192.168.2.1/21 WAN1 200.41.X.2/24 WAN2 200.41.X.3/24 ISP Gateway 200.41.X.1 This is a connection with 5 ...
2
votes
1answer
109 views

What is the correct iptables rule when NATing multiple private subnets?

I have a Centos minimal 6.5 acting as a router. eth0 is connected to a Cisco switch trunk port, allowing VLANs 200-213. I have several VLAN interfaces just as this link suggests: ...
-2
votes
1answer
185 views

One Public IP, Private IPs, DNS Server and Multiple Servers [closed]

I have lots of unanswered questions about these topics. So, lets begin. First off all, I'm not a server and networking guru. I'm a regular PHP developer. And I've read allmost all of the articles ...
0
votes
0answers
27 views

How to fix stalled connection on large download

I have a cisco 1921 router performing routing and NAT function. Cisco 3750 is performing layer 3 core switching duties. Users are complaining about large file transfers being stalled (not dropped) ...
0
votes
1answer
127 views

Cisco ASA Outside to Outside NAT (forward from one public ip to another public IP)

I have an ASA (A) with a set of public IPs (A1..A6). And I have another server S with a public IP (S1) . I want all traffic to A2:22 NATed (forwarded) to S1:22. (SSH is just an example here) If ...