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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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 in command: node --debug-brk=5858 main_server.js, and the output is: ...
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iptables settings for Tomato

I am trying to figure out the iptables settings for my router. Right now I have two networks, a home network on br0 and eth1, and a guest wifi on br1. Home IP addresses are on 192.168.1.x, and guest ...
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11 views

Access two web servers (VPS and Windows Server) through the same IP (PUBLIC AND VPN) using VPN

I have two servers: a hosted VPS with a website on port 80 and a home server running Windows 7. The home server is running WAMP on port 88, which works on my home's public and local IPs. When ...
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19 views

How can I control specific traffic like UDP traffic with iptables on ubuntu?

If for example I would like to send just the UDP traffic to an IP-address, is it possible to do this with iptables ?
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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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How to Ban an IP address automatically in ubuntu 12.04 when it sends specific packet to server?

I run a game server and someone is attacking with fake players. I want to ban him automatically in Ubuntu V P S. Any IPtables command or program that can accomplish this task? If it's not possible ...
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32 views

linux: how to troubleshoot forwarded port?

My home internet connection has a static IP address (eg: 123.123.123.123) I have configured my router to forward port 9000 to an internal host (192.168.1.101), which is running Ubuntu 14-04. I run ...
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12 views

Block traffic to LAN but allow traffic to Internet (iptables)

On my home network I am setting up a CentOS server that will be used by about a dozen or so for educational purposes - e.g. learn how to use the Linux shell and host websites, among other things. I ...
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23 views

About network traffic control

I have a satellite internet connection -> a pretty nice 8 processor server with 64gb of ram, running debian 7.7, two lan ports, one connected to the gateway, the other to the wifi router, wifi to all ...
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34 views

Map remote host to local ip (linux)

How can I map remote host to local ip? For example: If I map google.com to ip 192.168.1.15 so when i ping 192.168.1.15 i get forwarded response from google.com Maybe Iptables or something?
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Connections from virtual host to internet OK, but to rest of LAN, broken

In a notebook running Ubuntu 14.04 I have installed VirtualBox and created a virtual server with Windows 7. The PC is connected to a 192.168.x.y LAN. The virtual server is in a host-only network with ...
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23 views

Config to make only pcap receive packet

I am trying to use pcap to modify the packet before sending it out. For example, I have a server (running Ubuntu) listening on port 8000. Before it sends out SYN-ACK for incoming SYN packet, I am ...
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39 views

iptables snat does not change source IP

I am on ubuntu (with IP 10.0.0.1) trying to snat packets going out from port 9090. I want to change the source IP to 10.0.0.2 I have added the following rule through iptables: # iptables -t nat -A ...
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1answer
27 views

Debian 7 - iptables 'filter' not supported?

Am attempting to forward/ masquerade connections from WLAN0 to ETH0 as follows: sudo iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE sudo iptables -A FORWARD -i eth0 -o wlan0 -m state --state ...
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18 views

Packets are delivered to the host, which has the (dst) IP, but the application bound to the IP/port never see the packets

I have an iMac and a dd-wrt router. On the Mac side of things I have a proxy executable that I wish to use, but I've been unable to figure out how to make pf forward packets to the same host. ...
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42 views

IpTables -j REJECT to instantly block the loading on user browser

I have been searching for a solution to notify the browser on user that the request is Rejected so stop loading it. Because I have blocked facebook and every page that have a facebook plugin is ...
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29 views

Cannot SSH on machine behind NAT. DD-WRT router

I'm trying to remote access my home Debian from my other office. The home Debian is behind a DD-WRT router, connected from a ADSL modem (Yeh, it's dynamic IP but I have someone to tell me the WAN ...
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How to block network traffic on ubuntu gateway via arp table

I have a network with 80 PC and a ubuntu 12.04 as GW. For security reason I want to limit the Computers connected on this network using an ARP precompiled table. In other words I want a tool that ...
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iptables Rules gets reseted after Reboot@Ubuntu Server

I made a entry in blockfacebook table to DROP 173.252.74.0/18. Now, I tried to remove it using iptables -D blockfacebook 8 (173.252.74.0 is in the 8th line) and then I viewed the iptables ...
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37 views

Routing specific port ranges to specific gateway on Asus AC68 router using iptables and ip route

Linux noob here. I was hoping someone could help me with configuring some routing rules on my router, an Asus AC68. The router is connected to two gateways, wan0_gateway and wan1_gateway. I have ...
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25 views

Why is the TCP open but not the UDP?

I'm setting up a game server and I have a bunch of ports forwarded already (all in use). So I'm putting one into /etc/ppp/firewall-masq, which is full of iptables rules. The game server is served by a ...
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21 views

IPTABLES NAT port forwarding

I'm trying to setup a Linux box to act as a very simple 2 NIC router. I've read over the instructions on the bot Archlinux and Gentoo wikis and gotten the same result, masquerading works but not port ...
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24 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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1answer
22 views

Trouble with last DROP rule in iptables

Let's say I want four ports to be opened for any incoming packets so I made this ruleset: #> iptables -L -v Chain INPUT (policy ACCEPT 20 packets, 1190 bytes) pkts bytes target prot opt in ...
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25 views

iptables do not block all traffic i want to mysql port

Need to block all incoming traffic to port 3306 but two ranges. The thing is I can connect from other ranges anyway!. Think my drop rule is ok. Why is this? ]# iptables-save # Generated by ...
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Port bridge with iptables

is there a way to achieve the same thing than bidirectional socat functionality with nc mkfifo backpipe nc localhost 42042 0<backpipe | nc localhost 1042 1>backpipe But only by using iptables ...
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1answer
54 views

Make application use specific network interface

I have an openvpn connection and I need it to work only for one application, this app uses an specific local port. I used route-nopull on my openvpn config file and then: ip route add default via ...
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1answer
18 views

Filtered port with virtual server setup on a NAT

I have a Symphony SY602 ADSL router and I want configure a dynamic DNS to access my system remotely. I made a NAT virtual server in routers configuration and this is what I configured: Server Name ...
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19 views

enable internet on openvpn tun - azure linux

I am trying to do this with OpenVPN TUN on an Azure Linux instance: -=Android Client=- --> -=VPS=- --> -=Internet=- Client connects but no internet access. Iptables commands iptables -t nat ...
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12 views

Linux: Can user applications generate icmp messages?

I am using TOR and setting up a transparant proxy depending on users. I had trouble to constrain ICMP messages on UID. But I found an explanation for that on server fault. For the sake of privacy: is ...
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21 views

Why does iptables port aliasing work with only a single rule?

I have a service running on a particular port, but in order to make it accessible via a more memorable port as well as the normal port, I added an iptables rule that acts as a port alias: iptables -A ...
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25 views

Open firewall port on Mac OS X

I need to open port 8181 on my Mac OS X. On Linux, I would do: iptables -t filter -A INPUT -p tcp --dport 1664 -j ACCEPT iptables -t filter -A OUTPUT -p tcp --dport 1664 -j ACCEPT How do I do this ...
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1answer
15 views

Can't connect to Monet DB hosted in RHEL5

I'm not a sysadmin, much less a RHEL sysadmin, but for some reason I have to make a few config changes in a couple RHEL servers. I have to set up a couple services in different RHEL servers and they ...
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13 views

How to forward DHCP broadcast messages between two interfaces using ebtables?

I have two interfaces, WLAN and LAN, on my linux system. How can I "forward" DHCP broadcast messages received on WLAN to LAN using ebtalbes?
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How can I configure one of the ubuntu desktops as “dhcp-relay-agent”?

I have two Ubuntu desktops U1 and U2. U1 is connected to a DHCP server using wireless LAN and U2 is connected to U1 using LAN cable. How can I configure U1 as a dhcp-relay-agent so that U2 can also ...
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MASQUERADING a veth

I want to bind an application to a wifi interface that might loose connection and receive a new DHCPed IP on reconnect. The problem is that the application can only be binded to an IP address and not ...
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25 views

How do I share my wlan0 internet connection to eth0 using command line and config files?

I understand how it is done using the GUI (1, 2, 3), but I need to do this manually using Linux tools/commands (iptables, eatables ...). What are the configuration steps and commands to use, ...
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Why am I getting “FATAL: Ident authentication failed for user ”root“” after changing rails server to port 81

I was running my rails app on the default port of 3000. I opened port 300 with: sudo iptables -A OUTPUT -o eth0 -p tcp --sport 3000 -m state --state ESTABLISHED -j ACCEPT and sudo iptables -A ...
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5 views

SSH tunnel data from hostapd server to remote server

I've set up a small raspberry pi with hostapd to be a wireless access point. I'd like to have all connections from it ssh tunneled to a server in another country. I'm not overly sure how I'd do this, ...
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34 views

Route all packets on port 80 from inside a vm to kali linux on another vm

I'm trying to route all packets on port 80 to kali linux so that I can ssl strip them but I cannot see to setup the iptables correctly to force all the packets to go to my other Vm. [ Virtual Machine ...
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29 views

iptables on debian blocking git pull, http api requests etc

I am using IPTables on an API server to block all incoming traffic except for SSH, HTTP and HTTPS. I need to have full access on the loopback interface to run beanstalkd amongst other things, and need ...
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82 views

How to force Google safesearch on entire network

I've a problem filtering web searches on Google domains. Currently I've a linux openVPN Server running with openDNS "family block". I can block a lot of websites with dangerous content and it's ok. ...
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1answer
49 views

Why my iptables configuration for port-knocking does not work?

I implemented the following iptables rules on my test server for a course. The firewall shuts down and I cannot access port 22. However, after knocking on the ports 1111, 2222 and 3333 in that order - ...
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188 views

OpenVPN won't connect from remote location

I set up OpenVPN on a linux machine in my basement. I'm able to connect from my Windows 8.1 machine without an issue when I'm connected to the local network. In this instance, I set the config file ...
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iptable definitions for routing and defence

I'm attempting to configure a firewall on my laptop that allows for routing. The main trick is, I don't want to allow for connections to be made that do not fall under the ESTABLISHED,RELATED ...
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34 views

Port mirroring without TEE

I have a home router running OpenWRT 12.09.1. The package list for this version does not have iptables-mod-tee. I am familiar that I could set up a port mirroring using: #-A POSTROUTING -t mangle -o ...
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1answer
21 views

Trying to configure iptables on Slackware 10

I am trying to configure iptables on a Slackware 10 machine. This Slackware version is required in my class - so I cannot upgrade it. After compiling it, I want to configure iptables - however, it ...
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55 views

Conntrack gets incorrect forwarding rules for outgoing protocol 41

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 ...
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1answer
111 views

allow incoming ssh with openvpn client

I have set up an OpenVPN client on my home router. The moment the tunnel goes up, I can no longer ping my router from the internet using its WAN_IP. I would like to allow certain incoming connections ...
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1answer
53 views

Using IPtables to redirect IP address range to port range

I'm trying to set up an IPtables rule that will forward all packets to a /22 range to a single IP and port for debugging purposes. Based on the question here Using iptables to redirect ip address I ...