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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Iptables: Filtering string encrypted by ssl

I need to filter (send to BANRULES set) incoming http/https packets with a certain string (matchword). I do it easy when ssl is not in use (port 80): iptables -A INPUT -p tcp -m tcp --dport 80 -m ...
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Configuring IPTables to exclude webhost from VPN tunnel

I have a Raspberry Pi running as a server for my webhost. Raspberry pi is connected to a VPN service 24/7. Due to this, I am unable to connect to my webhost using my public IP address issued by my ...
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How to block all ports except 80,443 with iptables? [duplicate]

Blocking all ports(in and out) is easy but it's hard with the word "except". I don't know any rules that satisfies the condition. PS: I know this question is nothing new. But in fact, I didn't find ...
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36 views

How to forward http request to a proxy server?

I have an Internet Linux server and my client computer (running windows) accesses internet via a SSH tunnel to the the server. Now for some reason this server can only accesses internet by a http ...
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Block all ports except SSH/HTTP in ipchains and iptables

How can I block all ports except ssh (port 22) httpd (port 80) using iptables and iphains?
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29 views

Clients unblocking AWS S3 Content on their firewall

I have a website that serves out user generated content from AWS S3. I have a client that wants to use our website from behind a firewall. They are asking me to provide them with a static IP Address ...
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44 views

Creating a login portal for my WiFi

Me and my room mate often have a lot of friends come over to our apartment to play games and what not. So we are talking a lot of devices connecting to my router (cell phones, tablets, laptops etc .. ...
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41 views

How can I configure one of the ubuntu desktops as “dhcp-relay-agent”?

How can I relay DHCP requests from LAN to WAN in linux so that the desktop connected to the LAN interface can have Internet access from WAN? Note: WAN has Internet access.
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28 views

DD-WRT route between vlan2:1 and vlan2

I've been trying to configure a Netgear R7000 with DD-WRT on board. My problem is the fact I have a private ip assigned to the WAN (vlan2) and a public ip assigned to vlan2:1 If I use only iptables ...
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39 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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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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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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27 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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33 views

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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54 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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134 views

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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51 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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24 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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281 views

Iptables limit user access time and mac

I am trying to create an iptable chain to kick my daughter off her ipad during the night. With the mac only filter I can block access but when I add time it no longer works. Does anyone see an issue ...
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46 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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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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88 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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26 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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3k views

iptables trouble: nat with ip alias (virtual interface) not working

I'm setting up an Ubuntu 11.10 server to act as firewall for a network running several different SSL websites. The idea is fairly common: have all public IP's for each site aliased to the public ...
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78 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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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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61 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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996 views

iptables not starting on CentOS 6

I am running CentOS release 6.5 (Final) and cannot figure out why my iptables is not starting. I may have executed some other command to permanently prevent the start up of iptables; I do not ...
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103 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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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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38 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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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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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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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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22 views

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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89 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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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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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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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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Block a user from accessing internet on Linux

How do I block a user from accessing the internet under Linux? I'm trying the following: iptables -A OUTPUT -p tcp --dport 80,443 -m owner --uid-owner $USERNAME -j DROP Is that the right syntax or ...
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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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53 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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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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Bandwidth limit by Port on iptables

What iptables function would I use to bandwidth-limit all traffic on port 566 to 2KB/s? I'm confused about exactly how to do this.
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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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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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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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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, ...