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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Is it possible to setup a NAT loopback on a router with a dynamic IP using iptables?

I've set-up a Raspberry Pi home server attached to my router. I have a dynamic IP. I can access the server within my network using the internal IP (192.168.0.8). I can also access the server outside ...
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Opening port in iptables doesn't work

I add the following line before COMMIT in /etc/sysconfig/iptables: -A INPUT -m state --state NEW -m tcp -p tcp --dport 80 -j ACCEPT Then I use service iptables restart to restart iptables, but the ...
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18 views

allow specific port past VPN while denying all other internet access

I have a local machine that connects to a VPN for internet access, and is configured so that it can't access the internet at all besides through the VPN, although the local network can be accessed ...
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1answer
39 views

Can't ping Subnet A from Subnet B with router between them

I experimented with subnetting in my home network and Raspberry Pi. The ISP Cable Modem has 4 eth-interfaces and 1 wlan interface which all seem to be switched together. The routers IP is 192.168.0.1 ...
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Securing bridged lxc container with iptables

For some reasons I need lxc containers which have the same IPs like the host itself and other computers in the internal network. Now, I setup so far the containers with a bridge which routes to veth ...
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Can I track the CPU load that IPTABLES firewall is causing?

Since IPTABLES is a software based firewall, I am wondering if it is possible to log the exact load it is causing, cpu cycles, etc. On a small system I am sure it is trivial. But how about with ...
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17 views

Can't Access Port number 80 and 443 after adding Iptables rules

In my CentOS 6 i added a IPtables rules like DROP all the policy like iptables -P INPUT DROP Then I allow Port NO 22,80,443 with this command, iptables -A INPUT -i eth0 -p tcp --dport 80 -j ...
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28 views

OpenVPN without NAT

I'm trying to figure out how to route OpenVPN clients without using NAT/PAT. What I want to do is to route the IP address that they are assigned when clients authenticate to the OpenVPN server to the ...
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19 views

Iptabes and PSAD [closed]

I have a couple questions regarding my iptables configuration. First off I am still relatively new to iptables configurations, I am going over guides and books but progression is slow. When I ...
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22 views

Too many connections from other IP addresses and my own IP address

I get thousands of connections from same IPs. It takes down my web server (Apache). How could I restrict 1 ip to open only 10 connections max using ip table rules? My 2nd issue is there are so many ...
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40 views

Linux - redirect SSH on a port to another machine on local network

I have a KVM guest machine on a virtual network. It has an IP address like 192.168.122.65. The host machine is connected to the public internet. If I open a terminal on the host machine, I can SSH ...
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Can't access my FTP Server due to change in value of IP_MODULES in iptables_config file

I could once access my FTP server usinf FIleZilla (FTP CLient) but couldn't upload files into it successfully. After trying the chmod 0777 and chown options and still couldn't upload files. I searched ...
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19 views

Netfilter/tc rule to separate SSH and SFTP traffic?

When I connect to my server (RasPI 2 with Raspbian) remotely, I want my interactive SSH sessions to always have priority over any running SFTP sessions. Also, SFTP sessions should have less priority ...
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18 views

Linux: Don't allow any non-vpn traffic

I tried the search, as I'm sure this has been asked before, but I couldn't quite find a working answer. I wish to drop any connection that is not routed via VPN (with the sole exception of the ...
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22 views

Stopping multiple IPs from getting logged on iptables log

I want to log all dropped packets with my iptables (by default all except ssh), but I want to exclude the local network IPs as well as 0.0.0.0, 255.255.255.255 and 192.168.0.255 from appearing in the ...
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20 views

iptables not able to load conntrack match

I have a problem using iptables like this: iptables -m conntrack iptables v1.3.8: Couldn't load match `conntrack':File not found Now I wonder how I can debug this. This is what I have tried. ...
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37 views

iptables on CentOS 6.6

I'm trying to open a port on CentOS, but it doesn't seem to work: port 16 seems to be closed and 4075 seems to be open, even though according to iptables it should be visa versa. Chain INPUT (policy ...
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How can I read out the value of internal counter inside ipset

I know there is an option named "counters" when creating a ipset. However, I want to know how to read the value of the counters out, so as to know how many packets or how much data has been forwarded ...
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22 views

Most efficient way to proxy a port from one host to a port on another

I have a host with one IP address which is using port 443 (HTTPS) with one certificate. I want to run a second app on this IP address using a different certificate on a different port. To prevent ...
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1answer
40 views

Routing subnet to specific routing table with fwmark, direct to ISP and VPN

Introduction I'm trying to set up a VPN on my router so that I have two routing tables. I want it so that all the filtering is done with iptables, and iproute just acts on the specific fwmarks, ie ...
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RaspberryPI OpenVPN Client Not Forwarding to tun0

reposting from the RPI SO - apparently off topic for Server SO... I found plenty of guides for how to run RPIs as OpenVPN servers, but I want to run it as a client. I have a OpenVPN server set up ...
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26 views

3 interface server - wap with bridge - how to route this?

I have the following setup (except the "server-addressed packets"-part): http://www.directupload.net/file/d/4062/jo9qswvv_png.htm Basically eth0, eth1 and a wap. eth1 and wap are bridged with br0. ...
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Error mounting NFS unit between synology server and Raspberry Pi client

I'm trying to mount an NFS (v4, or v3.. but get the same error...) from a Synology Server to a Raspberry Pi client. But I get this error: mount -t nfs4 IP_address_of_server:/volume1/nfsnvf ...
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SSH port block: port forwarding

I need to access SSH on machine A within another port than 22, because there are only the standard ports allowed to access from the network I use. Therefore, I want to route port 443 of machine B to ...
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Forward VOIP phone on eth1 over OpenVPN (tun0)

I have a remote computer connecting to my network via OpenVPN. This computer is running Linux Mint, and has two network cards: eth0: used for Internet connection eth1: has a VOIP deskphone plugged ...
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36 views

IP masquerading, rule to forward packets between the Interfaces (on a multihomed network device)

Preamble This question can be considered as a followup to link Setup System: Embedded linux system running netfilter and iptables enabled kernel. Number of interfaces: 2 eth0: Connected to a NAT ...
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26 views

OpenVPN iptables and security

I want to run OpenVPN at home. I have a virtual instance of Debian 8 on my ESXi 6.0 host with its primary IP as 10.0.0.99. I assigned multiple virtual NICs (server, vpn, management, backup) with the ...
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1answer
55 views

iptables - allow access to a web server from the outside

I am trying to allow access to a web server from the outside and I am getting nowhere. Granted I do not have any experience in iptables, but I have dabbled in Cisco ACL and NAT. I am not sure what I ...
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55 views

How to route traffic from one interface to another regardless of source ip?

I asked this question on network engineering, but they told me it was off-topic there and I should therefore try on superuser. So, I'm deploying some raspberry pis for a specific network task. I'm ...
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26 views

ssh into local machine from remote maching

I would like to ssh into my local machine, from a remote ssh shell. by looking at ifconfig $ ifconfig wlan0 Link encap:Ethernet HWaddr 60:d8:19:24:bd:8b inet addr:137.44.181.163 ...
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58 views

Allow access across subnets not working

I have two routers. One is running DD-WRT and the other is running Tomato. The DD-WRT router is the main router the WAN connection goes through. The Tomato router is for my PIA VPN. DD-WRT is a ...
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Why does iptables not doing DNAT for the same subnet?

I have the following NAT setup: Whereas Host 1 has a VM with IP 10.0.0.3 and HOST 2 has a VM 10.0.0.4. The NAT box will have a NAT rule such that it changes the dest IP 172.24.4.2 to 10.0.0.4: -A ...
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36 views

Redirect Https requests?

Being a noob for such considerations, please dont hit me... I have redirection from many domains --to--> a unique landing page of my server. This works painlessly for http Here is my question : ...
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1answer
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Making a two-way bridge between two interfaces

so i wish to bridge a connection, I made a quick drawing of my setup: (eth0 isn't connected to anything) All of the computers are running centOS 7. Network Diagram I wish to allow PC A to ping and ...
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31 views

iptables redirect blocked IPs from one chain to a honeypot

I am currently using psad to automatically block potentially harmful IPs. When it detects an attack it adds the ip to PSAD_BLOCKED_INPUT or PSAD_BLOCK_OUTPUT and then drops all further traffic from ...
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1answer
21 views

Allowing emails on iptables

I am trying to configure my iptables firewall (currently rejecting all traffic) to allow emails traffic. For SMTP port 465 is used (SMTPS port), and for IMAP it uses port 143. But whatever I try, I ...
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How forward packets from network interface to another

My problem is forward packets from eth2 that is my LAN to eth1 that has access to internet, to allow eth2 to access to internet, here my configuration: auto eth1 iface eth1 inet static address ...
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Why put ACCEPT target after DROP in iptables?

My iptables -nvL looks like this: bash# iptables -nvL Chain INPUT (policy ACCEPT 1031 packets, 81085 bytes) pkts bytes target prot opt in out source destination ...
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1answer
40 views

bridge WAN interface with TUN interface except openvpn port

I want to make a bridge between eth0 (static WAN) and tap0 (TUN), but leave 1194 port for openvpn on eth0. Is it possible? How to achieve it using iptables?
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iptables does not redirect my HTTPS request

I configured my tables to redirect all traffic to a static IP. for ports 80, 443 + any port (NAT-DNAT redirect withour having specified ports). If I enter an IP:anyport or an url.ext, it does ...
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How to ensure iptables DNAT redirect all, to work with domains?

When redirecting all sources (any port) to my router IP, it works with IP. I do this with iptables, Nat/DNAT PREROUTING. $ iptables -t nat -A PREROUTING -i wlan0 -p tcp -j DNAT ...
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NAT iptables : why wrong/empty destination in saved config?

Here is rules I put in iptables : $ iptables -t nat -A PREROUTING -i wlan0 -p tcp --dport 80 -j DNAT --to-destination 19.11.11.1:80 $ iptables -t nat -A POSTROUTING -j MASQUERADE ...
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openwrt using iptables with tee seems broken

I've been trying to set up port mirroring on openwrt version 14.07 following this guide: however the command: $iptables -t mangle -A POSTROUTING -o br-lan ! -s 192.168.0.0/16 -j TEE --gateway ...
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What is MASQUERADE made for?

A simple redirection is used on my server, with iptables rules : $ iptables -t nat -A PREROUTING -p tcp --dport 80 -j DNAT --to-destination 13.37.42.1:80 $ iptables -t nat -A POSTROUTING -j ...
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ipTables, how to block all services requests on port 80 for an IP?

On a linux server/router, I want to block port 80 only for one IP (example : 1.2.3.4 ) I have been given this example : ### Block Incoming Port Requests (BLOCK PORT) # To block port 80 only for an ip ...
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Unhappy mixture: linux, tuntap, namespace,pppoe

I have created three namespace(ip netns), x, y z and a ip bridge called brig0. I am trying to route packets to the pppoe connection in namespace y. I want to know why tun0 says "no-carrier"? How can ...
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39 views

Connection interruptions on Debian router, possibly due to excessive duplicate ACKs?

I have a Debian server as a house router, which for a year has been working flawlessly. However, I recently moved and switched service providers from FiOS to Comcast, and possibly as a result am ...
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116 views

How to passthrough Wifi DNS and internet access to DHCP client

I have a laptop that connects to wifi for internet access. This computer is running Linux (Fedora), and it is acting as a DHCP server for another (ubuntu linaro) computer that does not have a wifi ...
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OS X iptables owner equivalent OR use only vpn for specific user

I am trying to make sure all network traffic initiated by a specific user on OS X Yosemite will go through a specific vpn or otherwise be blocked. I imagine I could do that easily on linux using ...
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how to port forward to server + tunnel specific hosts route though openvpn client on tomato

Running Shibby Tomato v130 on an Asus RT-N66U. My goals are the following With Transmission running on the router have all torrent traffic route through an OpenVPN client also running on the ...