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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1answer
306 views

FreeBSD jail with IPFW with loopback - unable to connect loopback interface

I am trying to configure a one IP jail with loopback interface, but I am unsure how to configure the IPFW rules to allow traffic to pass between the jail and the network card on the server. I have ...
1
vote
0answers
68 views

Weird socket behavior in VirtualBox (NAT + PAT)?

I have a Linux VM with NAT and PAT configured. Let's say ports 2000 and 2001 are forwarded to the VM. These ports are also configured for external access on a device such as a router using a domain ...
0
votes
1answer
73 views

2 NIC vs NAT for exposing server

I'm trying to virtualize some applciation using citrix. so I have to expose the secure gateway to Internet (put it in DMZ). my question is which is better practice ? 1 - using 2 physical NIC, one ...
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0answers
58 views

With split routing configuration returning packets don't reach their sender

I am trying to configure a split routing setup, where all traffic goes out the default eth0 interface, while packets from a single client are routed via tun11 (OpenVPN interface). So far I've come up ...
0
votes
1answer
97 views

can I use DNS with private NAT addresses?

I want to build a service that dynamically creates VMs and assigns each VM a public DNS record which could be a full domain or a subdomain. Assume the VMS all live on a single host. The VMs will have ...
1
vote
0answers
48 views

Poor large transfers behind NAT on Centos

I have the following set up. A Centos 6.5 VM running on an ESX host, with a public IP4 address. It is acting as a gateway for (a bunch of) other Centos 6.5 VMs that are only connected to a virtual ...
-5
votes
1answer
60 views

NAT444 on vodafone 3g [closed]

I am using Huawei K3765 with vodafone as ISP. When i tested my IP with ipconfig, private IP is assigned to me. I dont think this device act as a router, since its just a 3g donle. This created the ...
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0answers
50 views

Is there an optimal NAT configuration in Cisco IOS for peer to peer applications?

The Cisco router in my organisation is set up to use Port Address Translation (PAT) for Internet connectivity. ie All outbound internet connections are from the ip address or the border Cisco ...
1
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0answers
2k views

[SOLVED ]Openvpn routing for lan to lan through tun

I am trying to setup an OpenVPN tun to connect two lan's The open vpn connection is up and working but there is a problem with my routing or nat or something. What I need is an example of what a ...
5
votes
3answers
4k views

iptables nat does not exist

Today my iptables nat on the host system stopped working and I have no clue what happend! (That's very bad, I know) All commands are executed as root user. If I run $ iptables -t nat -L I get the ...
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votes
0answers
30 views

Impact of iodined settings to server

I would like to install iodined, the IP tunnel via DNS, on a working web server. However, the configuration requires to set IP forwarding add NAT masquerading rules to iptables (and open DNS port) ...
-5
votes
1answer
301 views

Why Are There Only 65,535 Ports, and Will We Ever Have More? [closed]

I understand the original reasoning behind having 65,535 ports per IP address: this is the highest number that can be represented by a 16-bit, or 2-byte, number, and it wasn't conceivable that ...
1
vote
1answer
63 views

Websever behind Sonicwall, Gateway Timeout

I am stuck here, I have a Cradlepoint CBA750B in IP-passthrough mode connected to x1 on my Sonicwall NSA220. Behind the Sonicwall I have a webserver on the LAN. I have X1 set to use DHCP to get the ...
0
votes
1answer
434 views

How accessing a NATed, virtualized (LXC) server over public IP from client itself on a bridged network?

Setup ____________________________ ____________________________ | Host | | Client | | Public IP: 66.66.66.66 | ...
1
vote
1answer
105 views

Redirect traffic from one server to something.cloudapp.net (CNAME) [closed]

Through out North America, we have lots of legacy devices, which sends data to our server which has static IP Address. Now we are moving to Azure cloud services, and as you know they do not guarantee ...
1
vote
0answers
96 views

Firewall and NAT settings in GSM modem for one server

I have a GSM Modem (PSI-MODEM-GSM/ETH) in field with one device behind, acting as a server. The situation is as follows: "PC" | \_________Dynamic IP: 10.103.153.122 | ...
0
votes
1answer
130 views

CISCO: conditional port-based NAT (policy-based PAT)?

I have a problem to nat-translate inbound http packets to different local_ips based on some condition (like dscp bits set). Actually the dscp bits get set on the incoming trafic using NBAR. I hope ...
1
vote
2answers
91 views

Communicating between two servers sitting behind their respective NATs

I'm building an web app (Server A) that communicates with a remote server (Server B) that is connected to the internet. Server B resides behind a NAT and is listening to communication on 3 ...
-1
votes
1answer
120 views

iptables NAT table not matching anything [duplicate]

I am attempting to take a TCP service running on port 1234, and make it appear as if it's running on port 81. I thought the following might do it: iptables -A PREROUTING -t nat -p tcp --dport 81 -j ...
0
votes
1answer
63 views

Software for emulating networks and NAT

I am working on a software that I need to test with different types of NAT, and I would like to set up a test environment I can reconfigure in different NAT modes. I would like to have: ...
0
votes
1answer
56 views

How to avoid hairpin VPN on cisco

I currently have a hairpin VPN setup with a Cisco ASA, but I'm not very happy as it messes up service access that are on ASA external IP address and are NAT'ed inwards :( How should I re-design the ...
0
votes
1answer
58 views

iptables NAT forward range

I have two network interfaces, eth0 and eth1. eth0 has a public ip, eth1 has 172.16.0.254/24. I'd like to do the following mapping: 172.16.0.1:22 -> eth0's public ip:2001 172.16.0.2:22 -> ...
0
votes
1answer
141 views

Iptables/ufw - blocking ports when using nat

I use NAT to move requests from external ports to an internal ip address and port hosted with proxmox. Something like this: iptables -t nat -A PREROUTING -i vmbr0 -p tcp --dport 8000 -j DNAT --to ...
0
votes
0answers
28 views

Is it possible to hairpin on Cisco 851W IOS 12.4(15)T9 and how?

I need machines on the LAN to be able to access by the external address or hostname. If it can't be done, then just by hostname is OK as well, so I thought of just doing it through DNS on our internal ...
0
votes
1answer
459 views

iptables forwarding through virtual interfaces

I'm trying to configure my computer as a gateway between two networks, but I cannot make it working for some reasons Here is a representation of the network: 192.168.1.101 192.168.1.102 ...
0
votes
1answer
148 views

access same subnet on different interfaces

I have a router with external (WAN connection) subnet 192.168.1.0/24 and also on same router a tunnel to a remote location which have the exact same subnet (192.168.1.0/24), and i need from my LAN to ...
0
votes
0answers
100 views

FTP Traffic routing through NAT prevents me from logging in

I need to send all FTP traffic to a particular server from a NAT. Server A connects via FTP to an IP which is routed to the NAT and then over a VPN. That traffic then comes back and gets routed from ...
1
vote
0answers
73 views

strongswan packet get natted when ufw is enabled

I'm using strongswan 4.6.4 to connect road warriors to my server (ubuntu 13.10), which is natted behind a firewall. left=%defaultroute leftsubnet=10.10.1.0/24 right=%any ...
-2
votes
1answer
156 views

Dead-simple Juniper firewall hairpinning [closed]

I have a SRX100 firewall running JunOS 12.1. I have a WAN interface proxy ARPing ten or so static routable IPs. I have a LAN interface on a simple class-C subnet (we'll call it 192.168.0.x). I'm using ...
1
vote
0answers
52 views

OpenVPN running on Internet Gateway, so all private clients can access VPN with no config

Our LAN connects to our office gateway machine (192.168.1.1), which is connected to the Internet. I have setup NAT/Masquerading for this purpose with no issue. We also use OpenVPN to connect to our ...
0
votes
0answers
46 views

Cisco IOS log packets dropped due to no NAT entries?

I use access list logging currently, and update the access list to match the NAT table, and then the access-list deny any any log command is used for logging packets that were not allowed. However, I ...
1
vote
1answer
153 views

Access Apache VirtualHost from localhost

I have a DirectAdmin setup with Apache on a server which is behind NAT. Everything is working correctly when accessing a VirtualHost from outside the machine (either through the Internet and the ...
2
votes
1answer
43 views

Should we accomodate a customer asking us to NAT servers behind new PUBLIC IPs within a VPN?

We're a SaaS provider, setting up a IPSec VPN between our data center and a customer's site so they can directly access their hosted database server from their LAN. Instead of exposing our internal ...
1
vote
1answer
138 views

how to forward proxy requests using iptables

I've this schenario ----------------- ---------------- ---------- | SERVER A | ---(port:2128)> | PROXY | ---> | INTERNET | | (10.30.1.1) | ...
0
votes
1answer
70 views

Cisco ASA 5510 nat

In my infrastructure, I natted a server on a Public IP address. Please note, the server is reachable from any outside network. My access rules are good. My isssue is from the internal network, I'm ...
1
vote
1answer
2k views

Asterisk and SIP behind NAT

I am trying to Setup an Asterisk-Server to accept calls from a client in an other Network. The Server and the client are behind an NAT. I have already activated STUN on the client, but I am still ...
0
votes
2answers
40 views

Forwarding all connections to different address

I have a script that tries to connect to rabbitmq using default url and port (localhost:5672). Is it possible to make linux redirect all connections to this url and port to different server? I am ...
1
vote
1answer
190 views

Linux iptables DNAT stops working after some time

3 down vote favorite I have a strange behaviour in my server setup. It looks like that. client1 192.168.11.2/24 <----> 192.168.11.7/24 (br1/vlan1) Server 192.168.21.1/24 (br21/vlan21) <---> ...
0
votes
2answers
191 views

Portforwarding with IPTABLES and Remote IP detection

I was able to forward 80 port from my primary server 192.168.90.1 to the second one 192.168.90.2 with IPTABLES The primary server has a public address X.X.X.X so I forwarded X.X.X.X:80 -> ...
0
votes
1answer
1k views

strongSwan setup where both sides are behind NAT

I'm trying to setup a strongSwan server in my home and connect to it from another network. Let's say sun is the VPN server and venus is the client. Both sun and venus are behind NAT networks. sun is ...
0
votes
2answers
117 views

Forward web request to another computer

I have one notebook and two servers: ip = 172.17.0.2 (I have installed nginx here) ip = 172.17.0.3 (There is nothing here, but I can ping 172.17.0.2 from here) I open browser on my notebook, open ...
0
votes
1answer
99 views

How do I know that my TCP connection is safe from the Firewalls/NAT?

Being on the Azure cloud, I found that the firewalls there drop connections between the Web server and the database quite often. Mostly when there was some inactivity, I think something between 5 and ...
2
votes
2answers
207 views

Internet VPN Tunnel with a server behind NAT

Let's say someone would like to route all their traffic traffic though some PC in another country (to unblock some sites). However, this PC is a usual Windows 7 PC behind a router with NAT, which ...
0
votes
1answer
135 views

How to apply port forwarding with iptables on existing connections?

For load balancing purposes, occasionally our servers forward requests to a different port; The default port for our service is port 5000. This is the code used: iptables -t nat -A PREROUTING -p tcp ...
0
votes
1answer
178 views

Configure atftp server to reply on port 69

Problem : I'm facing to a problem with TFTP server and Cisco 79XX IP phones. When on a local network, everything is working fine, but when the TFTP server is on a public server (and phones inside a ...
0
votes
0answers
18 views

client does not respond server's syn_ack package

pc to access the server through a NAT device。 client has successfully established a tcp socket with server using this port , and the server's interacted with the message well, socket has been closed ...
1
vote
1answer
274 views

How can I know if NAT instance is becoming a bottleneck

I'm running my own NAT instance inside of an AWS VPC. I want to make sure that the NAT instance will not be a bottleneck and to that end would like to set my own expectation for when to scale to a ...
1
vote
0answers
142 views

Simulating a client behind a NAT in Virtual Box

I am trying to simulate a client behind a NAT using Virtual Box. I have a host machine let's say with an IP address 130.0.0.1. I create a virtual machine (let's call it VM1) running Ubuntu 12.04 with ...
0
votes
0answers
142 views

Load-balancing PPTP connections

I'm trying to load balance two PPTP connections, connected to the same server. I use the following script, but there is no send and receive via PPTP connections. What part am I doing wrong? Are there ...
-2
votes
2answers
174 views

Iptables MASQUERADE: What is the advantage/disadvantage between these two commands? [closed]

What is the advantage/disadvantage between below 2 commands: iptables -t nat -A POSTROUTING -o eth0 -s 10.0.0.0/16 -j MASQUERADE AND iptables -t nat -A POSTROUTING -j MASQUERADE Some Background ...