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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Need a proxy server for only logging requests

I have looked at Squid and find it too heavy for the simple task that I have at hand. I just need a proxy to run on Ubuntu, preferably a transparent one, which will only log http requests and nothing ...
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6 views

iptables limit number of outgoing connections on a port

I'm currently using the following to limit the number of incoming connections on port 9001 to 900. iptables -t filter -I INPUT -p tcp --syn --dport 9001 -m connlimit --connlimit-above 900 -j REJECT ...
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7 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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18 views

WordPress won't load unless iptables is disabled

I am running CentOS 6.6 using nginx. WordPress will not load unless iptables is disabled. I tried to add the 9000 port for fastcgi, but that did not work. I am guessing it has something to do with ...
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11 views

Use IPTables FORWARD for NFS

I have this topology [R1] -> [F1] -> [Server] I need to pass ssh, web and nfs traffic through F1 to Server using iptables. It's quite easy with ssh and web but I'm stuck with nfs. I have set static ...
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Confusion about the `conntrack` extension of `iptables`

The iptables-extensions manpage has this to say about the conntrack extension (emphasis mine): This module, when combined with connection tracking, allows access to the connection tracking state ...
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15 views

How do I know if certain iptables extensions are available and enabled?

I was reading this: https://help.ubuntu.com/community/IptablesHowTo#Allowing_Established_Sessions It says "If the line above doesn't work, you may be on a castrated VPS whose provider has not made ...
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12 views

Make traffic go one-way by using iptables

I have a network topology: [C1] - [R1] - [R2] - [C2] C1-R1 network is 192.168.100.0/24 R1-R2 network is 10.9.8.0/30 R2-C2 network is 192.168.200.0/24 What I need to do is to make C2 be able to ...
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27 views

CS:GO SRCDS and iptables (firewall)

I have very strange problem. This morning I wanted download, install and host small server for CS:GO on my VPS. I used this tutorial: ...
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6 views

Port Forwarding using iptables

I have the following problem: I have two servers. I can connect to server A trough the internet. But I also want to connect to server B. How can I use iptables, that if I connect to server A over ...
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25 views

Where do port knocking services listen for incoming knocks?

I'm trying to understand how a port-knocking daemon is able to monitor for knocks, independent of the firewall rules (e.g. accept/drop/reject packets). I've installed knockd, which listens for lets ...
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11 views

Limited network connectivity when SSHing through an OpenVPN tunnel

I have setup an instance of OpenVPN with a public IP to allow access to a private subnet on Amazon EC2. I am able to SSH onto machines on the private subnet through OpenVPN but when I do I have ...
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14 views

How to redirect traffic to a fixed IP address in Fwbuilder

I'm new to fwbuilder and I want to redirect all incoming wifi traffic to my web server. I tried many iptables command but I've failed so I came up to GUI firewall. Can anyone suggest how to do it?
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16 views

Manage NAT using a tool

I have a Raspberry Pi on which I had previously installed Raspbian and am now installing another version on again. It is mainly used to be a test maschine for small programs and primarily as a NAT ...
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16 views

OpenVZ cotainer and NAT

I have been trying to days to solve my NAT issue with OpenVZ. I have used their guide on their website/wiki, however I just seem to be unable to get it to work. My Linux box is running on CentOS 6 ...
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1answer
13 views

iptables: Routing requests to localhost:8080 to google.com

I am trying a simple routing rule that would forward the requests to localhost:8080 to some external address (ex google). I added the following rule : sudo iptables -t nat -A PREROUTING -p tcp -d ...
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13 views

Guest as Virtual machine connection to Host

I have guest run on my machine on qemu with configuration: /usr/local/kvm/bin/qemu-system-x86_64 -enable-kvm -cpu host -smp 8 -hda ${TEST_VIRT_ENV_IMAGE} -m 4096 -netdev user,id=user.0 -device ...
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22 views

Forward all traffic from one Linux interface to another?

I have a virtual ESX interface "eth1" that I want to act as a gateway for connections, and then route all of the traffic from these connections out of my "eth0" (WAN) interface. Here are my ...
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116 views

Connecting my Xbox 360 to my Raspberry Pi 2 to use an OpenVPN connection

Here is my brief setup: Xbox360 Raspberry PI 2 running ArchLinuxARM (alarm) The raspberry pi's main ethernet port has a cable connecting directly to my main router The xbox has a cross-over cable ...
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27 views

Tor Middlebox: How to check if there is a DNS leak?

I created a tor middlebox. Laptop plus WLAN. Creates a WLAN AP all traffic from that AP should be routed into tor. But I am not sure, if the DNS requests are not leaked. How can I check that? This ...
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30 views

tor middlebox: How to route traffic through a socks proxy automatically? iptables routing wlan

I built a tor middlebox. It is an old laptop without screen, creates a WLAN and every traffic on that WLAN is routed into tor. my iptables script: iptables -t nat -A PREROUTING -i wlan0 -p udp ...
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65 views

ssh: connect to host * port 22: Connection timed out

I have CentOS 7 running on a VPS machine and after a computer restart, I could no longer SSH to it. $ ssh -v <IP> OpenSSH_6.6.1, OpenSSL 1.0.1e 11 Feb 2013 debug1: Reading configuration data ...
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2answers
54 views

Traffic redirection with Rasperry Pi router

I use a Rasperry Pi (running raspbian) as a wi-fi router. It redirects traffic from the Ethernet wire (eth0 - wire + ppp0 - L2TP connection, lx2tp used for it) to wlan0 (USB wi-fi dongle, hostapd used ...
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24 views

Connecting router traffic to sshuttle tunnel

I am using sshuttle to get cleanly out of a questionable hotel wifi connection. I have a little travel router and would like to use it as well, briding my laptop's sshuttle connection so I can connect ...
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32 views

CentOS as home network router: IPTables Port Forwarding failure

I have currently set up a home server with a CentOS 6.6 installation on it. The server has two NIC interfaces which I'm using it as my router and DHCP server. Here's a diagram showing the network ...
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19 views

NAT Rule for PPTP Port Forwading

I'm under a very heavy firewall where only very common ports such as 21 and 80 are open. I installed PPTP on my own dedicated server (a Debian Linux) and I`m trying to connect it using Windows, but ...
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https proxy setup in NAT-ed clients

I have network setup as follows: I have 2 PCs. A and B. A is connected to Internet, and A and B is connected by local network. B can also connect Internet through A by NAT setup. In A, the NAT setup ...
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15 views

Create a VPN tunnel from ethic to wlan0

I have a lan network of which all internet traffic has to be routed through a openVPN tunnel. I use a RPi, and have setup ethic with a DHCP server, and can connect clients. Currently I use a lan0 to ...
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26 views

iptables default rules understanding

What does the last part in the following rules means in term of traffic that is allowed in (dtp:domain, bootps) ? From my research I understand that bootps is bootstrap and dpt is destination port but ...
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16 views

IPTables and SIP Proxy-Authorization Header

Is it possible for iptables to check SIP packets for Proxy-Authorization headers, and if there's more than one header in a SIP packet, modify the packet so only the latest Proxy-Authorization header ...
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35 views

port forward from host to libvirt guest virtual machine that is bridged to the host nic

I am having no luck getting access from the outside to a http server running on my network in a Debian virtual machine that was created through libvirt. This what my network looks like: PC1: running ...
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38 views

Forwarding some ports and websites from “eth0” to “wlan0” with IPTables

I have eth0 and wlan0 devices in my work laptop. eth0 access the company's network and it comes with the whole firewall rules and so on. So I’m unable to use Skype, Google Hangouts and other things I ...
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42 views

Set up port forwarding on Ubuntu with ufw

I want to route HTTP traffic from port 80 to port 8080. I added the following rule to /etc/ufw/before.rules -A PREROUTING -p tcp --dport 80 -j REDIRECT --to-port 8080 But it works only if direct ...
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44 views

iptables - How to mirror all ports from one IP to a single port on another IP

I would like to set up IP tables on my router to mirror traffic on all ports from 192.168.1.30 and send it to 192.168.1.10:5860 I think I need to combine the two commands below, but I'm at a loss. ...
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90 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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19 views

How to see who's blocking my internet connection? fail2ban?

I was just running apt-get dist-upgrade from a distant ssh console when I lost the connection. I would like to know which service blocked my connection. I know fail2ban is sometime a bit flaky, but ...
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46 views

Why CSF blocking all traffic?

I've installed CSF firewall with Directadmin. when the firewall is running, it blocks all the incoming and outgoing connections. My iptables -L -n: Chain INPUT (policy DROP) target prot opt ...
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60 views

Unable to Telnet to the Linux SUSE from windows with port 50000

Firewall has been disable at Linux SUSE server, port numbers from 50000:60020 has been enabled. I can able to ping the server able to telnet using IP. When I give port 50000 or 60000 in my telnet ...
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30 views

iptables TCP flags

I'm beginner with iptables and networking so please excuse me for such dump questions. I found in Internet part of filtering malformed packets: /usr/bin/sudo /sbin/iptables -A tcpchk -p tcp ...
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47 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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73 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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37 views

+Merlin FW / Port Forward via IPtables?

I have 2 WiFi Thermostats, Heatmiser, that i can control remotely, from LAN without issues, but only one from WAN. The thermo have a fixed port that cannot be changed and there is an App thet can be ...
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27 views

rsyslog loses messages from firewall

I am trying to make rsyslog to log messages from iptables MASQUERADE. I have iptables LOG rule in nat table and PREROUTING chain before the MASQUERADE rules. The actual iptables rules: iptables -t ...
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1answer
40 views

MaraDNS- Unable to forward DNS queries

I tried forwarding DNS queries to Google DNS but it is not working. Below is the content of my /etc/mararc file: csv2 = {} csv2["example.net."] = "db.example.net" csv2["google.com."] = ...
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Cannot access DNS from external network

I have setup a MaraDNS instance on CentOS 6.5. I can access the DNS records from local machine—on which MaraDNS is installed—by doing nslookup but cannot access the DNS server records from Internet on ...
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94 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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38 views

Route Specific URL to another interface on Linux

I have a Raspberry Pi Model B running Raspian. RPi is in between of my local network and Internet Router (as gateway; so all traffic is passing from RPi's eth0 interface to virtual interface eth1). I ...
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14 views

Determining whether a port is closed (no one is listening) or iptables reject my host

Can I tell whether the service I'm calling has a reject rule in its iptables or it doesn't listen on the port I'm calling? it seems that I always get icmp port unreachable
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25 views

iptables - Cannot redirect with 443 (Https) port

I'm using this command to redirect all web traffic (http and https) to my local server iptables -t nat -I PREROUTING -p tcp --match multiport --dports 80,443 -j DNAT --to 192.168.11.100 But when i ...
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1answer
51 views

Using ppp0 via VPN for everything but ftp

I have an ubuntu server I use to wget certain files from the internet via a VPN. I have set the VPN up using PPP0 and currently adjust the route like this: sudo route add default ppp0 Everything ...