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

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Block all outgoing traffic for a User running Wine apps

Good day, I'm using a lot of WINE apps under Linux which work just fine, but one thing I am specifically looking for right now is to block their access to the internet (outgoing), with exception of ...
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157 views

Iptables error :libipt_cgroup.so doesn't exist while using net_cls.classid in net_cls cgroup subsystem

In kernel document doc/cgroup/net_cls.txt, it introduces the function of net_cls.classid, and show an example of netfilter (iptables) using this tag to perform actions. the command of iptables is: ...
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3k views

How do I configure DD-WRT to forward IPSec traffic to an internal server to support a road warrior configuration?

I use dd-wrt as my home router setup and that's been working fine. Now I wanted to figure out a way to be able to use my iPad to set up a IPSec tunnel to my home network while I'm on the road. PPTP ...
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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. ...
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24 views

Simulate SNMP Trap with SNAT

I have to test SNMP 2c Traps. I want to send those traps from some computer and the trap destination has iptables. So before the trap enters the NMS, I could just rewrite the real source of the trap ...
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132 views

How do I block with specific string with IPTABLES?

Want to block this URL STRING with IPTABLES. Need to know specific command. "GET /affiliate/5/campaigns?api_key=duO5gVw3s0&affiliate_id=67647&format=json HTTP/1.0" 404 785 "-" "Dalvik/1.6.0 ...
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547 views

VPN does not reconnect (cannot resolve host address)

maybe someone can help me: At the moment i am trying to configure a fail-safe VPN connection to a commercial VPN provider on a virtual machine. This is working fine, until my router wants to reset my ...
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108 views

Routing traffic around VPN

I recently setup a OpenVPN client on my HTPC, however once I connected to the VPN server I was no longer able to remotely SSH or connect to the other servers I had running on the HTPC. I followed ...
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129 views

Modify incoming packets before forwarding in Linux

I’m using a Linux (Debian based) system on which IP forwarding is enabled (/proc/sys/net/ipv4/ip_forward is set to 1). I can read the incoming packets using a raw sockets program, but I want to modify ...
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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 ...
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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 ...
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357 views

Limit bandwidth on HTTP downloads based on file size

Is there a way to limit lets say in iptables or any proxy solution/software if a user is downloading a filesize that is greater than lets say 20MB it will limit his entire download at 2KB/s? ...
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322 views

Centos iptables blocks after reboot

I have a Centos5 installation with kvm on my server. I am using nat portforwarding to ssh my virtual machines. I have several iptables rules and saved then in /etc/sysconfig/iptables. After reboot, I ...
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824 views

How do you add a MAC-based routing whitelist with DD-WRT and the OpenVPN client?

I have an OpenVPN client set up on my DD-WRT home router which maintains a VPN into my workplace. Slight problem: I don't want random lusers who access my wireless AP to have access to my company's ...
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17 views

Can I track the CPU load that IPTABLES firewall is causing?

Since IPTABLES is a software based firewall, I am wondering if it is possible to log the exact load it is causing, cpu cycles, etc. On a small system I am sure it is trivial. But how about with ...
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28 views

OpenVPN without NAT

I'm trying to figure out how to route OpenVPN clients without using NAT/PAT. What I want to do is to route the IP address that they are assigned when clients authenticate to the OpenVPN server to the ...
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21 views

Too many connections from other IP addresses and my own IP address

I get thousands of connections from same IPs. It takes down my web server (Apache). How could I restrict 1 ip to open only 10 connections max using ip table rules? My 2nd issue is there are so many ...
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3 views

How can I read out the value of internal counter inside ipset

I know there is an option named "counters" when creating a ipset. However, I want to know how to read the value of the counters out, so as to know how many packets or how much data has been forwarded ...
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21 views

Most efficient way to proxy a port from one host to a port on another

I have a host with one IP address which is using port 443 (HTTPS) with one certificate. I want to run a second app on this IP address using a different certificate on a different port. To prevent ...
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28 views

Error mounting NFS unit between synology server and Raspberry Pi client

I'm trying to mount an NFS (v4, or v3.. but get the same error...) from a Synology Server to a Raspberry Pi client. But I get this error: mount -t nfs4 IP_address_of_server:/volume1/nfsnvf ...
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54 views

How to route traffic from one interface to another regardless of source ip?

I asked this question on network engineering, but they told me it was off-topic there and I should therefore try on superuser. So, I'm deploying some raspberry pis for a specific network task. I'm ...
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258 views

how to port forward to server + tunnel specific hosts route though openvpn client on tomato

Running Shibby Tomato v130 on an Asus RT-N66U. My goals are the following With Transmission running on the router have all torrent traffic route through an OpenVPN client also running on the ...
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57 views

502 bad gateway after putting up firewall nginx

My server was working, then I added a firewall for a bunch of ports! And now I get the error: 502 Bad Gateway nginx/1.4.6 (Ubuntu) Nginx server { listen 80; server_name 45.79.80.140; ...
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32 views

Iptables: dropping/rejecting new and invalid connections

I'm very new to iptables and my goal is the block NEW and INVALID connections on the INCOMING chain and log any attempts for a NEW connection. I'm also letting any and all traffic out on the OUTGOING ...
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55 views

Why do my nat iptables rules not work with marked packets?

System: debian squeeze, Linux server 2.6.32-5-amd64 #1 SMP Tue May 13 16:34:35 UTC 2014 x86_64 GNU/Linux, iptables v1.4.8 lsmod | grep iptable iptable_security 2176 0 iptable_mangle ...
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69 views

Use Ubuntu Iptable to route public ip to pc in private network

I am currently set up a Ubuntu server as a Router which has two network interface. eth0 -> Connecting to public internet ( 10.10.1.78 ) eth0:1 -> 10.10.1.79 eth0:2 -> 10.10.1.83 eth0:3 -> 10.10.1.81 ...
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20 views

tcpdump capturing packets only when interface is specified

I have tried 3 different ways of capturing a stream of packets coming into my server. Two of them work and the third does not. I am trying to determine why it is missed by the third approach: ...
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332 views

DDWRT - Virtual Interface - firewall command - RDP

I have DD-WWRT flashed on my Linksys e2500v3 router. I added virtual interface to create a guest wifi network that would have access to the internet, but not to the private network or router. At ...
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111 views

iptables TCP flags

I'm beginner with iptables and networking so please excuse me for such beginner questions. I found on the Internet part of filtering malformed packets: /usr/bin/sudo /sbin/iptables -A tcpchk -p tcp ...
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178 views

Windows firewall rule order?

I'm trying to setup Windows Firewall to allow all traffic except a large list of IP ranges connecting to/from a specific application. For testing, I set up two rules: Allow all traffic (no ...
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186 views

Configuring iptables for guest WLAN in DD-WRT

I'm constantly failing to get a guest WLAN in DD-WRT working. I can connect to the second SSID and get an IP address of the second DHCP server range. But I cannot connect to the internet. I followed ...
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164 views

Open ports with iptables — still closed

I'm trying to open some ports for a gameserver, which is running on my Linux vServer (Ubuntu 14.04 LTS 64bit). The game needs the following ports: 16261 (UDP) 16262 (TCP) // Player 1 16263 (TCP) // ...
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63 views

How to configure iptables to set public IP for outgoing traffic from private IP

I have multiple public IPs at home: 1.1.1.1 (main IP) 2.2.2.2 (additional IP) In my local network, I have two computers, let's say 192.168.1.1 (PC1) 192.168.1.2 (PC2) Infront of the computers I ...
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122 views

how to capture “DROP”ped packets on OUTPUT of iptables?

having a fairly complex OUTPUT processing on iptables, how does one go about capturing / displaying (at least similarly to how tcpdump captures them) the packets that were to leave through an ...
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127 views

Limit connections per second with iptables/ufw

How can I tweak the following entries to allow more requests per second? Maximum hitcount is 20 if you do not edit some other config files. The entry of my /etc/ufw/before.rules file -A ...
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125 views

Nodejs remote debugging ports closed

I have a problem with nodejs remote debugging. I'm using centos on remote server and phpstorm on my PC. When I open putty I type the command: node --debug-brk=5858 main_server.js, and get the ...
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26 views

Preserve NAT mappings across reboot

My Linux router is able to reboot and reconnect all network interfaces pretty fast (~10 seconds, thanks to systemd and a SSD disk), and comes up with the same IP addresses. Unfortunately the reboot ...
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34 views

IP rule table look up does not seem to work

I have a sytem with three network interfaces. Below is the configuration that I'm trying to set up. wlan0 (its actually an WiFi AP interface) - other devices connects via this interface. net1 - ...
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29 views

Is it possible to know a user logged in on Ubuntu instantly?

In fact, I am trying to restrict access to some websites for different users. I asked the question: Restrict access to some websites for different users. The given answer is ok; but as the owner ...
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0answers
124 views

Site to Site VPN - Openswan and CISCO A2A

Below is the diagram that the VPN connection between Openswan server and CISCO A2A. client A and B are remote hosts with static ips. client X and Y are behind the Cisco firewall. I can see ...
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476 views

Intermittent disconnections when using OpenVPN over SSH tunnel; possible iptables issue?

I've recently set up a Debian Wheezy server with OpenVPN to help out some friends in areas where internet censorship is a problem (including the blocking of VPN traffic in general). To overcome this, ...
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243 views

iptables configuration on Windows Azure (CentOS 6.5) for endpoint load-balanced set

I created 2 VMs (CentOS6.5) on Windows Azure for Postgresql database and HA cluster, everything works fine except when I set iptables service on, the endpoint load-balanced set is down. for security ...
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210 views

Allow internet access to intranet only users using Nginx on Ubuntu

I need to allow some users who only have access to the intranet to access one specific internet site. I'm doing this by using Nginx as a reverse proxy. To test this, I would like to block all internet ...
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249 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 ...
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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 ...
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198 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 ...
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276 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, ...
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189 views

“iptables -P OUTPUT DROP” blocks DDWRT's web interface

When I do iptables -P OUTPUT DROP it blocks DDWRT's web interface. That is I am not able to access http://192.168.1.1 via Firefox. I put this rules before changing the chain policy to drop: ...
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240 views

using iptables to filter vboxnet (virtualbox host only network)

Im trying to use iptables to filter the traffic coming from a guest OS running on virtualbox. The guest is configured to use a host only adapter for the network, and my Ubuntu host is configured to ...
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361 views

Ping through GRE tunnel discarded between 2 interfaces of a router - Ping does not reach subnet

I have an interesting issue that I hope someone can help with. I am trying to create a GRE tunnel between 2 routers (running Linux Ubuntu 12.04) and pass traffic between 2 subnets trough this tunnel. ...