iptables allow creation of rules to define packet filtering behavior.

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DDOS defence with iptables

I have server with Debian 6 with a many games servers and sadly, I'm getting ddosed. So, there is my ask for help. I want make solid firewall, where my server will safe.
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27 views

On a router, what decides if a packet should be forwarded or directed into the router itself?

I'm trying to learn how packet routing works on a linux-based router (OpenWRT in my case) a bit better for setting up a few projects/just-learning. Referencing the below chart, I'll break this into ...
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2answers
46 views

Is it possible to have multiple virtual machines with the same (guest) ip on the same host?

What I try to achieve: Multiple virtual machines (virtualbox) on a Debian host which communicate with another server (not with each other or the host). All VMs need to have the same static network ...
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CSF not blocking port when removed from csf.conf

I have removed VNC port 5901 from the csf.conf configuration file and executed a csf -f a csf -x and a csf -e to flush and restart CSF. There is a vncserver running on port 5901 and when doing an ...
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17 views

Does NAT allow accessing internal network (or router's local interface) from outisde by default?

I am using older SOHO router wl500gP (it is v1 but I think this is not important) with custom Oleg firmware. My topology looks like this: 192.168.3.3 192.168.3.2 NAT 192.168.2.1 ...
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26 views

iptables allow INPUT from a specific url

I'm using DD-WRT, and can telnet into it to add iptable rules. I'm looking for a rule that will allow IN from a specific address (say, mydomain.com) on port 80 that will point to an internal IP (say, ...
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44 views

how to automate creating firewall rules?

There is a complex live system - few vlans. In each of them there are linux servers, and on every server there are services. Services connect together - for example service http on host A connect to ...
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output in iptables

I have added the rule to iptables file, however the command does not show it. $ sudo less /etc/sysconfig/iptables Generated by iptables-save v1.4.7 on Fri Oct 24 13:28:48 2014 *filter :INPUT ...
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31 views

How to enable ping between machines connected in two interfaces?

I have a linux board with two ethernet interfaces as mentioned below. eth0 connected to another linux machine (ad-hoc) eth0 on board 191.168.1.2 connected to Linux machine 192.168.1.3 eth1 on board ...
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iptables | redirect from local [interface:port] to local [interface:port]

0 down vote favorite I have two interfaces eth0 (192.168.1.95) and eth0:1 (10.0.0.100) i want all packet for 192.168.1.95:9900 (from any 192.168/24) will be redirect/forward to 10.0.0.100:9900 and ...
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How to prevent an application from connecting to a network with iptables? [duplicate]

I have read the manual page of iptables in terminal, but it has complicated syntax and I don't fully understand how to use options like: user, user ID, UUID and so on. Suppose my username is foobar ...
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Shorewall configuration : providers and LAN

Hi all and thanks in advance for the answers. Currently, I have different providers configured in shorewall. I'll will probably have to change one of them. The problem is I won't have any Public IP ...
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Impossible to browse web after configuring iptables

I'm trying to configure iptables on my ubuntu computer. These are my rules: Chain INPUT (policy DROP) target prot opt source destination ACCEPT tcp -- anywhere ...
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1answer
31 views

Email evading my spam filter

I'm having trouble with email evading my Barracuda Spam firewall. I believe the spammers are using my A Record to bypass my MX Record which is what directs email to my Barracuda for processing. How ...
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1answer
33 views

Redirect user once using iptables

I have an access point (Raspberry Pi) running Raspbian (Debian). I need it to redirect user visiting specific website to another one, but only when the user visits the first site for the first time. I ...
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why do we have same chains in different tables of “iptables firewall” in linux?

why do we have same chains in different tables of "iptables firewall"? Like for example: we have "output" chain in filter table, nat table & mangle table.
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1answer
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iptables and RETURN target

I don't understand what the RETURN target does in a iptables command. The doubt comes from this guide where it says: A chain is a set of rules that a packet is checked against sequentially. When ...
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iptables - hairpin NAT dual WAN

Here is my lab Client LAN: 192.168.150.95 Gateway: 192.168.150.1 RDP Server LAN: 192.168.150.2 Gateway: 192.168.150.1 Linux Router WAN: 177.129.XXX.XXX Gateway: 177.129.XXX.XXX LAN: 192.168.150.1 ...
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Where can I find what the latest iptables version is?

I may be blind but I just can't see what the iptables latest version is. I've checked iptables homepage. I've also searched the internet and nothing.
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29 views

Unable to ping/SSH web-facing server

I just installed Ubuntu 14.04 LTS onto a box that's set up with one local NIC and one web-facing NIC. The web-facing NIC is configured with a static IP per my ISP. Because networking and security ...
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41 views

Problem with Squid in intercept mode on same machine as browser

It's been a while since I last set up squid cache. I'm trying to set up squid running in intercept mode on the same machine that I use for browsing. I think I've properly forwarded http requests to ...
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unable to block out-going traffic

I've run $ iptables -I OUTPUT -j DROP -d [ip address] and found that some processes are still connecting the destination ip I've blocked above: $ lsof -p [pid] it shows: ...
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How do you tweak iptables limit rules on openSUSE Tumbleweed?

I have a fresh install of openSUSE Tumbleweed, it is logging a lot firewall related stuff due to my apple devices multicasting to enable airplay. Lines look like: Mar 14 12:45:13 server kernel: ...
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9 views

iptables for Asterisk

I am running Asterisk with FreePBX. I would like to log all failed attempts and after a while ban them. Ideally after 3 failed attempts in 1 minute, ban for 1 hour. Is it possible to see if this ...
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1answer
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How iptables tables and chains are traversed

I know linux has 3 built-in tables and each of them has its own chains as follow: FILTER: PREROUTING, FORWARD, POSTROUTING NAT: PREROUTING, INPUT, OUTPUT, POSTROUTING MANGLE: PREROUTING, INPUT, ...
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54 views

Restrict the maximum number of independent IP connection on specific port at the same time

I set up a server as a socks5 proxy. I'd like restrict the maximum number(1 or 5 or 20) independent IP connection on specific port at the same time. I have searched on google, only see some articles ...
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93 views

monitor bandwidth on interface with tc or iptables

I would like to log a warning message to /var/log/messages file if either ingress or egress bandwidth on eth0 interface is over a certain threshold. I could do this with a script which reads the value ...
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44 views

Best way to transparently redirect traffic to proxy

I've implemented a wireless router using hostapd on Debian Wheezy running on a Banana-PI. To access the internet, this router is attached to another network that I haven't any control of via ethernet. ...
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2answers
49 views

How to disable network access for a user?

Trying to disable the network access for the user: [root@notebook ~]# iptables -I OUTPUT -m owner --uid-owner tempuser -j DROP [root@notebook ~]# ip6tables -I OUTPUT -m owner --uid-owner tempuser -j ...
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failing to tunnel F5VPN through OpenVPN

summary I need to tunnel an F5VPN through an OpenVPN in order to ssh from a client device (Debian laptop) through a firewall. The OpenVPN works, but I lose all networking on the laptop once I start ...
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9 views

iptables-save return with errno 1 - operation not permited

When I run the command iptables-save it returns with errno 1 - opearation not permitted If I do: iptables -L and then: iptables-save then iptables-save succeeds This error happens only ...
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41 views

Redirect traffic through the server

My task is to redirect traffic (port range) through the server. Here is the schema: Why NAT is not appropriate here: If NAT is set to "Tunnel Server", then all users will be assigned the same IP. ...
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28 views

Config iptables ssh over VPN

How can I define a rule that only allows ssh via VPN in iptables? My iptable Rule is following: #!/bin/sh IPT="/sbin/iptables" $IPT --flush $IPT --delete-chain $IPT -P INPUT DROP $IPT -P FORWARD DROP ...
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1answer
47 views

Switching between Network Interfaces

I am trying to write script to switch between two interfaces on a Linux machine, wlan0 and eth0. My primary reference is: http://askubuntu.com/questions/338100/forwarding-traffic-between-2-interfaces ...
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24 views

Nat with saving real client IP

I have this schema: Client -> NAT server -> Game server On NAT server I have the following rules: iptables -A FORWARD -d $MC_IP -p tcp --dport 25550:25580 -j ACCEPT iptables -t nat -A PREROUTING -d ...
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1answer
77 views

iptables allow only ssh and vpn traffic

I have dedicated server with ubuntu 14.10 installed. The server should connect to an openvpn server and the traffic should only go through the vpn, except for SSH traffic. My idea is to realize it ...
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52 views

Get real IP after OpenVPN tunneling

I try to route traffic from one Server to another using OpenVPN. In the end users should only connect to the forwarding machine. It basically works using this iptables rules: iptables -t nat -A ...
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34 views

how to block only certain outgoing ip connection with iptables

(Centos 5.5) to block xxx.xxx.xxx.xxx: # iptables -A OUTPUT -j DROP -d xxx.xxx.xxx.xxx then verify by: # iptables -L OUTPUT --line-numbers Chain OUTPUT (policy DROP) num target prot opt ...
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1answer
34 views

NAT External IP to local server using iptables

I have a adsl connection with static IP (lets say 1.1.1.1). My debian firewall connects Internet with ppp and IP is assigned to firewall directly; ppp0 Link encap:Point-to-Point Protocol inet ...
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43 views

Why is traffic matching the public zone instead of the desired zone?

Trying to self-train on firewalld I set up apache and configured the zones as follows: [root@localhost ~]# firewall-cmd --get-active-zones work sources: 192.168.122.1 public interfaces: ens3 ...
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83 views

Why do iptables drop / log even if the appropriate packet should be accepted?

I'm setting up a server running Debian Jessie with some applications like iptables firewall, fail2ban, openvpn, apache, ... The iptables firewall is configured in the way, that it logs every packet ...
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57 views

OpenVPN Server only Serves traffic from Google.com to Client

So I am pretty sure this is a routing/config problem. Whenever my client (Android OpenVPN) connects to the OpenVPN server it can only retrieve traffic from google.com searches. Whenever I try and ...
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21 views

DHCP occasionally assigning IP address with hostapd

I am currently getting my internet from a building of mine two blocks from where I live. I usually use a wireless card to connect to the access point that has the internet..What I am trying to do is ...
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0answers
57 views

iptables: No chain/target/match by that name

I'm trying to configure iptables to get Redsocks working {purpose is to get system wide socks proxy} #!/bin/bash # Create new chain iptables -t nat -N REDSOCKS iptables -t nat -A REDSOCKS -d ...
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1answer
83 views

Iptables can't forward from/to internal LAN with proxmox

I have an host with proxmox with single public ip and some virtual machine installed whit webservers and multiple doimains, the first VM is a proxy with haproxy that forward the request to other VM ...
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1answer
54 views

IPTables Firewall/Router/Gateway needing to block outbound traffic from users

I have multiple ethX interfaces. eth0 is connected to the internet. eth1 is connected to a trusted network. eth2 is connected to a network I need to impose usage rules. What I'd like to do is ...
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1answer
117 views

forward packets from one interface to another interface using iptables

I have an embeded system with 2 interfaces e0 and m0, whose ips are 10.0.0.20 and 192.168.0.20, respectively. Incoming packets into e0 have an ip of 10.0.0.10 and should be forwarded to m0 interface ...
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34 views

PPTP Through IPTables

If this has already been answered, I apologize, I could not find an answer to this during my searching. I am new at Linux/Unix and I have recently implemented a Raspberry Pi firewall/gateway on my ...
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36 views

iptables - How to remove connection tracking

I'm using this command for redirect all web traffic (http) into my local web server iptables -t nat -I PREROUTING -p tcp --dport 80 -j DNAT --to 192.168.11.100 Then i test, access a website and got ...
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72 views

iptables - Redirect web traffic to LAN Server

I have a webserver which is running on ip address 192.168.11.100 How can i use iptables to redirect all web traffic (http and https) to my webserver on LAN? After that i want to add except list mac ...