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 drop packets by IP protocol type

Is it possible to have iptables rules to drop packets by IP protocol type as described in [http://www.tutorialspoint.com/ipv4/ipv4_packet_structure.htm]? (ICMP is 1, TCP is 6 and UDP is 17, but what ...
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Using iptables to allow LAN and drop WAN of unknown devices

I posted this over on stackoverflow but it was off-topic. I have looked around and couldn't find the answer to my question. I am using a raspberry pi as an internet gateway between my LAN and two ...
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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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271 views

slow internet access when routing via a server (both using iptables NAT and ssh tunnelling)

I have a spare computer powered by a dual core intel atom N550 CPU and 2GB RAM (I will refer this as "the server"). It is running lubuntu 14.10 x86 (32 bit) with lightdm service disabled (hence, no ...
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65 views

How do you force linux to treat a tcp packet as if it were at the destination ip?

The situation: A tcp packet arrives on eth0 with destination 8.8.8.8. This packet meets some criteria that makes me want to intercept it (lets say I am interested in all packets from source 10.0.0....
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2k 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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841 views

DDWRT - OpenVPN connects, but can't communicate

This seems to be a popular topic, but I can't find any solution to the same problem I am having. Here's the setup: I have a DD-WRT router (build 14896) on a linksys WRT54GL. I have one file server ...
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299 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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160 views

Iptables rules suddenly not working

I'm trying to set up a webserver using an Odroid U3; as OS I have Debian 7.4. The issue came when trying to load the iptables rules with iptables-persistent. I'm using the same file with rules I've ...
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219 views

Block archive.today From Crawling My Site?

My website is being scraped by archive.today. This site is similar to the reputable archive.org, but archive.today does not obey robots.txt, spoofs a generic user-agent and tried to hide its IPs. The ...
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159 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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143 views

iptables always needs restart

I have a CentOS 7 PC, on which I'm using iptables. I have an Oracle 11gR2 instance on that PC and I need to access is from other PCs in the LAN. My /etc/sysconfig/iptables: # Generated by iptables-...
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3k views

Can ping but can't connect (curl, wget, apt-get, etc.) (rasberry pi server)

Background: I am trying to set up a rasberry pi server. Everything was going well and my pi could apt-get update etc, until I got the port forwarding to work and ssh to work outside of the LAN. I ...
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249 views

iptables out bound port to remote mysql

Following is my iptables file on my centos, I am unable to open 3306 port to connect to remote mysql server. I dont know what I am doing wrong although it looks fairly simple. When I stop the iptable ...
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74 views

Share Internet through Arch Linux VM

I'm working with a LAN which is behind a router that I don't control. The router admin has allowed internet access to one IP address 192.168.0.50. I would like to create an arch linux VM at that ip ...
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123 views

Iptables newbie pain

I got a host (WINDOW7) and a guest (DEBIAN7.7) virtualized by VirtualBox. I configure an eth1 interface as host-only. My host can ping the guest and vice-versa, host can connect via ssh too. Now I ...
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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 ufw-before-...
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468 views

Port Forward inside Router (DD-WRT)

I have configured an SSH tunnel on my DD-WRT router using the default port 22. I would like to open another port on my router as a proxy port for SSH, say port 80, in case a firewall prevents me from ...
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67 views

IpTables: rule to allowing outgoing traffic

I need rule to allowing outgoing traffic from intranet addresses 192.168.X.X to foreign addresses 123.123.123.0-63 and by using tcp Protocol. Sorry for bad english Thanks
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206 views

Remove iptables rules from recovery system?

I have a remote dedicated server and accidentally added some iptables rules that killed network access. I am only able to access SSH in recovery mode, which gives me access to the filesystem. I can't ...
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425 views

Can a Linux machine have two the same IP addresses on different interfaces/networks?

Is it possible to have two the same IP addresses and subnets assigned from two different interfaces/networks? How would such machine behave? How would route table look like?
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Blocking 127.0.0.1 in iptables?

I'm in the process of setting up some rules for iptables. Not wanting to make any errors I am currently only logging activity. The logs have shown a number of entries for 127.0.0.1 hitting my rules: ...
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741 views

FTP does not work properly when connected to OpenVPN

I am connected to an OpenVPN server and would like to list all files on a FTP server. ftp> ls 500 I won't open a connection to 10.125.1.20 (only to 31.x.x.100) ftp: bind: Address already in use ...
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275 views

Cannot retrieve http sites when using OpenVPN, but https sites work just fine. Why?

I am using a VPN provider that uses OpenVPN. I don´t wont any other traffic leave my computer so I have set up my iptables like this: iptables -P INPUT DROP iptables -P FORWARD DROP iptables -P ...
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437 views

How to set up a hotspot with socks5 proxy

I have a laptop with linux installed on it. The laptop has two network interfaces: eth0 and wlan0. Normally I surf the Internet through eth0, and I've successfully set up a hotspot in linux for my ...
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92 views

How to print iptable firewall rules?

How does one print or dump the firewall rules being used by iptables in an effort to trouble shoot connection problems? I'm fairly certain its going to include -L or --list, but I'm not sure of other ...
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410 views

iptables - UDP Packets from unknown IP addresses

I'm really new to basic systems administration, and this question is a bit difficult for me to Google. I'm setting up a small raspberry pi server for my own personal use, to teach myself some basic ...
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64 views

What minimum'allows' should be used in iptables rules?

I have a Ubuntu 14.04 server which has two Ethernet ports: eth0 directly connects with a custom camera and eth1 connects via LAN cable to a wireless router. I had been developing a web application ...
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2k views

Openvpn connects and responds to ping but no internet access

I have an openvpn server running on raspian and a tunnelblick client on osx. I can connect to the VPN just fine but I have no intenet access. The server responds to ping just fine and the port is open ...
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391 views

how to save iptables rules permanently?

I want to keep some iptables rules permanence, so I just only add the rules manually: /sbin/iptables -I OUTPUT -p tcp --sport 80 -j QUEUE I am sure that the command works, because I could see it ...
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iptables duplicate traffic to another ip

This blog post has a template iptables rule to forward traffic, to and from the router to another ip address. iptables -t mangle -A POSTROUTING \ -d [IP to spy on] \ -j ROUTE –tee –gw [...
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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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How do I set Input interface is output interface

I have eth0 with IP X.X.X.X and eth0:0 with IP Y.Y.Y.Y. My goal is if I connect to eth0 then output ip shoud be X.X.X.X and if I connect to eth0:0 the output ip should be Y.Y.Y.Y. Example: VPN ...
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42 views

iptables INPUT command

On a ubuntu1, this is iptables command: sudo iptables -A INPUT -p icmp -j DROP so on the other computer (xp1) I can not ping the ubuntu1.So this is OK. But On ubutnu I [[ can ]] ping xp1. and I ...
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465 views

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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989 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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160 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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126 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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193 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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40 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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329 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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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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93 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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770 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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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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142 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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94 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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593 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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135 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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169 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 ...