Iptables is a module that provides the Linux operating system functions of firewall, NAT and logging of data traveling over a computer network.

learn more… | top users | synonyms

0
votes
0answers
1k views

iptables: Allowing multicast & other traffic on LAN, not to WAN

I have a Linux 3.10 machine functioning as a NAT router between the wlan0 LAN and the eth0 WAN. I would like to allow all communication between machines on the LAN (they are trustworthy) and allow ...
0
votes
1answer
134 views

iptables eth0 wlan0 bridge not working

I am trying to allow an embedded system to share the wireless of my laptop. The embedded system is an A20 Olinuxino Micro running Debian and my Laptop has Ubuntu 12.04. I tried this which has worked ...
1
vote
1answer
69 views

Transparently proxifying certain devices on the network

I'm using my computer as wireless access point and router to my home network using hostapd under Ubuntu 14.04. I want to transparently proxify certain wifi devices in the network (identified by their ...
0
votes
1answer
299 views

How to share ppp0 to wlan0 with redsocks

I can't understand the meaning of this: I have a USB modem along with a USB Wifi router, and I use redsocks for ppp0. Then I want to forward the incoming connection from Wifi to redsocks. I have ...
0
votes
1answer
166 views

Ports in Linux vs Windows

I'm studying for a security class. I know that ports in Linux are tied to a process. So if I wanted to close/shutdown a port, I'd end the process that's using it. So if I'm in Windows, what's ...
1
vote
2answers
142 views

How to check/adjust SSH server on embedded board

I'm currently having difficulties connecting to an embedded board from my Linux machine through ssh. The embedded board is a FOX G20 V with a Linux OS. I've tried to connect to the board through ...
0
votes
1answer
222 views

Redirecting internal traffic to gateway's port-forwarded external endpoints directly to intranet destination

There's an intranet and CentOS-powered gateway that provides connectivity for intranet devices. Typical port-forwarding in gateway's iptables ruleset looks like this (TCP version is provided): ...
0
votes
1answer
152 views

Granular routing with iptables and iproute2 over VPN

On a host at my house I have a host for a VPN that I need for a couple of purposes. Living temporarily in Japan, it functions as a NAT for some devices so I can still use my NETFLIX and some other ...
1
vote
1answer
899 views

iptables blocking all traffic even with ports opened

Simple as I can put it: I can't access my servers with iptables enabled, with default rules. Need to disable iptables to get access. Trying to find the cause. Only difference in setup type is layer3 ...
1
vote
0answers
251 views

Can't connect to web server from outside my network

I have a Debian-based server that I would like to be able to access from the Internet (no domain name yet, I'm just trying to get it working for now). I already have port forwarding set up on my ...
3
votes
4answers
3k views

bridge does not forwarding packets centos

I am using CentOS 6.5 64 and use xen to create a virtual machine (CentOS) ifconfig [root@CentOS ~]# ifconfig eth0 Link encap:Ethernet HWaddr 08:00:27:54:B3:FA inet6 addr: ...
1
vote
0answers
470 views

Conntrack/NAT's port mapping for a specific port breaks whenever that port's service is shutdown for too long. How can I fix this?

Linux Gentoo 3.13.6-hardened-r3 #1 SMP Sat Apr 12 09:17:25 EDT 2014 x86_64 Intel(R) Core(TM)2 CPU 6300 @ 1.86GHz GenuineIntel GNU/Linux hardened with grsecurity and selinux with a strict policy in ...
0
votes
1answer
111 views

How to specify a certain device to access the Internet via the OpenVPN client of router?

Involved Devices: a VPS, a router, and several devices that connected to the router. Final Aim: Base on the OpenVPN client which has connected to the server on the VPS, specify only one local device ...
1
vote
1answer
407 views

Iptables deny access to a specific IP address not working

I'm not able to deny access to a specific IP address or deny access to a specific IP address range as well. My network environment is, I have one router which IP is (30.30.10.1) and second my hotspot ...
0
votes
1answer
2k views

Route internet traffic from openvpn tun0 to eth0

I can't figure it out. How do I give chosen VPN-users access to internet trough eth0? All server traffic goes trough eth1. The eth0 is only supposed to give VPN-users internet access on chosen ports ...
2
votes
2answers
3k views

Apache runs locally but can't be accessed from other machine

I'm running Apache 2.2.3 in a VM for a test environment on CentOS 5. Apache is running and responding to requests on the VM itself. If I run "lynx localhost" on the VM I do get my test page. When I ...
0
votes
1answer
915 views

configure iptables to block all(as much as possible) bittorrent traffic

good day all This is my current iptables setup Generated by iptables-save v1.4.7 on Wed Apr 9 13:50:31 2014 *filter :INPUT DROP [0:0] :FORWARD DROP [0:0] :OUTPUT ACCEPT [0:0] :LOGDROP - ...
1
vote
0answers
201 views

Segregating/Separating a device (ATT 3G Microcell) from internal network without using DMZ

I would like to put the ATT 3G Microcell in an isolated network from a network that has the rest of my devices, by which I mean I want the ATT 3G Microcell to only be able to access the Internet, but ...
0
votes
1answer
318 views

IPtables preventing outgoing packets

I am trying to setup firewall rules on a RHEL webserver, so that my webserver can serve up web pages and at the same time download remote files using curl/wget. Problem I am experiencing is I can only ...
0
votes
1answer
895 views

Routing internal traffic in centos to the internet using iptables

Hello friends i am struck in routing traffic from the office to internet i have a network structure like this http://asthana.me/images/ip.png I have assigned static ip to the cent os server(which ...
-1
votes
1answer
283 views

Bind incoming packets to 1 interface and outgoing packets to 2nd interface?

I am have a Linux machine with 2 network interface cards, I need to use one for incoming packets, other for outgoing packets.
0
votes
1answer
84 views

Turning iptables off on development server permanently?

What would be the downsides of turning off iptables permanently on a development environment? I don't like the fact that every time I restart virtual box I must do: service iptables stop service ...
2
votes
1answer
731 views

How to forward ports through ssh and nat to another machine

I have a problem when using ssh port forwarding and nat simoultaneously. Situation: Machine A runs a webserver on port 8080 Machine B is a raspberry pi which works like a little router. It has two ...
1
vote
1answer
205 views

Connected to vpn but can't connect to internet

I am using ubuntu 12.10 as a vps. And I am trying to configure a vps server on it. I can connect to the vpn but just can't get internet access. Maybe because I don't know how to write a iptables. ...
0
votes
0answers
41 views

Blocking an outbound port for a bridge'd nat'd inteface

eth0 and wlan0 are bridged to br0, and have access to the outside world through eth1 and NAT. I'd like to block an outbound port on wlan0, but leave it open for eth0.
0
votes
1answer
151 views

packages from router dont match iptables dnat rule

I have the follow rules to forward port 443 from external to a internal host: IF_INET=ppp0 IF_INET_IP=1.2.3.4 # Router External IP IF_LAN_IP=192.168.0.1 # Router Internal IP ...
1
vote
0answers
277 views

How to stream WiFi cameras over a Linux gateway to my laptop using iptables?

My setup is as follows: Linux gateway has one WLAN configured as WiFi client (192.168.0.100) to a Linksys WiFi AP(192.168.0.1). There are three WiFi cameras connected as WiFi clients (192.168.0.101, ...
2
votes
0answers
1k views

Synergy client won't connect, despite open port?

I want to use a Debian KDE desktop computer (network name bradbury) as the server, and a Windows 7 laptop (network name Clarke) as the client. I have used this setup before without problems, but then ...
0
votes
1answer
300 views

Editing IPTABLES nat rule in cron job

I am sitting here with an issue: I need to switch the source interface for iptables' NAT rule at a given time. I want to basically do soemthing like this - caution: concept code: #!/bin/bash if [ it ...
1
vote
1answer
124 views

Unable to ping server

I have a Linux server that seems to have lost the ability to respond to a ping.. I recently installed Nagios on another system and need to have this Ubuntu server answer up to a ping.. I'm using ...
2
votes
0answers
121 views

Determine if an uplink interface is usable

I have a firewall system that is served by two uplinks to different ISPs. I'm using shorewall to manage the firewall; it load-balances traffic over both interfaces with connection tracking. All that ...
0
votes
1answer
141 views

why iptables is accepting all in INPUT?

As we can see in this, which is the default iptables on fedora 20 $ iptables -L INPUT --line-number Chain INPUT (policy ACCEPT) num target prot opt source destination 1 ...
2
votes
1answer
1k views

How to transparently tunnel a port from IPv4 to a remote IPv6 device?

At home, I am connected with an IPv6 address and additionally, my provider provides a NAT-like setup through which I receive a public IPv4 address that I share with other customers (the reason being ...
2
votes
1answer
895 views

What does this iptables rule mean: tcp flags:0x06/0x02 TCPMSS clamp to PMTU?

What does this iptables rule mean: tcp flags:0x06/0x02 TCPMSS clamp to PMTU? Doing iptables -vnL on my DD-WRT router shows the following rule in the FORWARD chain: TCPMSS tcp -- * * 0.0.0.0/0 ...
1
vote
1answer
903 views

How to create a local-remote-local tunnel to a specific port using ssh

I'm able to establish an ssh connection from my windows computer (localhost - eth1) to my linux computer (remotehost - eth0) by doing: ssh user@192.168.1.100 Instead of using that, because I use ...
1
vote
2answers
560 views

Is Iptables blocking outgoing ssh connections?

I have been trying to do pulls from github and it keeps hanging. My iptables rules have no rules which block outgoing traffic but I cannot connect to github using either ssh or http. I can't even ...
1
vote
1answer
89 views

Forwarding all traffic to other server with iptables

Assume I have a sever with X.X.X.X IP address and a web server with Y.Y.Y.Y IP address. How would I forward web traffic from X.X.X.X to Y.Y.Y.Y using iptables? My servers run Linux and use iptables
2
votes
1answer
73 views

When writing an iptables save file by hand, how does one calculate the packet-counter and byte-counter values?

I am attempting to write a 22MB iptables rule-set file, the very kind that is generated with the iptables-save command, except endlessly long. Understandably, this takes a prohibitive amount of time. ...
0
votes
1answer
859 views

IPTABLES forward all ports except ssh

I have nat and packet routing working just fine, but I'd like to forward all ports except SSH to a static ip(192.168.0.3) What would be the correct iptables syntax to do this?
0
votes
1answer
3k views

Forwarding all incoming traffic on eth0 to go to eth1

I am trying to setup my raspberry pi to sit between my router and my modem. I'm basically trying to set it up as an intercepting proxy so that all web traffic goes through the proxy. I have the ...
3
votes
0answers
2k views

Route outgoing VPN traffic through local transparent proxy

I have a Digital Ocean droplet (similar to an Amazon EC2 instance) running Ubuntu Server 12.04.3 x64 with both strongswan 5.1.1 (built from source) and squid 3.4.2 (also built from source) installed. ...
1
vote
1answer
415 views

bind/named not working on UDP from external

This one is weird. I've set this up a long while ago, on a centos5. From what I remember, it used to work. For some time now, it's not. I've just been informed so no clue what changed when that made ...
1
vote
1answer
156 views

iptables password protection followup

This is a follow up on my other post about this iptables: plaintext password protection I could not get help in the old topic...I just really need some help... Here is the command I tried, something ...
1
vote
1answer
157 views

Use IPTables to force TCP packets over router

To test a TCP-stack program, I need to get the TCP packets via the router. When I try to connect to my server program via the router, the OS does not hit the router as the destination IP is the same ...
0
votes
3answers
1k views

How to configure iptables correctly

I'm a newbie to linux.I just implemented the following commands in iptables which I found on a site for security (i don't understand much about how each rule works). The commands are as follows: ...
0
votes
1answer
185 views

Per application rules in iptable

Is there possibility to add rule via iptable for specific process name? Good explanation of why I need it is here: "Under Windows, this helps making the PC more secure. There are many ...
2
votes
2answers
719 views

Connecting to an SSH server behind a NAT

I am having trouble connecting to an SSH server behind a NAT on an ubuntu workstation. I've installed openssh package(both the client and the server) and forwarded port 22 through the NAT and tried to ...
1
vote
2answers
1k views

Is selective VPN routing worth it?

I want to setup routing tables on my RT-N66U router to selectively route traffic through a VPN. For instance, only Pandora requests would go via the VPN. I've found a way to do this with iptables: ...
0
votes
1answer
179 views

Routing traffic over Vpn without NAT?

I want to tunnel traffic through my vpn but I just realized that my kernel does not have nat enabled ;( iptables -t nat -A POSTROUTING -s 10.20.0.0/24 -o eth0 -j MASQUERADE iptables v1.4.14: can't ...
0
votes
1answer
1k views

How do I block every connection except vpn and ssh without endangering the state of my vps?

I have some vps space but I get alot of scans based on what I see in iftop. I tried some iptables stuff but it gets tiring and useless to put all the ips that I see in the logs. I am wondering about ...