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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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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56 views

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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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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70 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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186 views

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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61 views

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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42 views

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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256 views

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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58 views

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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50 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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26 views

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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97 views

iptables block access to all ports except 53 (tcp,udp) from one IP address

how can i block all ports from one IP address except the port 53 TCP,UDP? example: ip 192.168.0.15 access only port 53 (udp,tcp). thank you.
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36 views

Automated Wifi on Raspberry Pi

I have a NAT set up, that allows my devices to bypass the MAC filter in the local dormitory router. The setup works, but since my original "nat server" has died (the HDD got fried), I had to put my ...
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49 views

How To Configure Portforwarding with iptables

I have got a "Hypervisor" witch has two interfaces: eth0 Link encap:Ethernet Hardware Adresse d4:3d:7e:fc:b2:db inet Adresse:87.25.34.251 Bcast:87.25.34.255 Maske:255.255.255.192 ...
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166 views

DSCP to p bit mapping in Linux

Re posting from Networking forum as per suggestion Linux1--------------------------------------------Linux2 eth0 10.10.10.30 eth0 10.10.10.10 eth0.50 20.20.20.30 ...
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96 views

Bypassing VPN routes based on the destination port

I have a Raspbian machine connected to a VPN using OpenVPN. Without any configuration, all traffic goes through that VPN and I have no control over the VPN server. What I'm trying to achieve is ...
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101 views

How to set up iptables to open ports 80 and 443

I try to understand how iptables works but after a lot of hours and readinga lot of articles I have stuck. What I want to do is DROP INPUT & FORWARD policy and open some ports. More specifically, ...
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131 views

Iptables SNAT routing to openVZ containers

For this to make sense I need to set the scene a bit. I have a dedicated server with 5 public Ips : A.B.C.1 to A.B.C.5 A.B.C.1 manages the dedicated server itself, and A.B.C.2 - 5 are used for ...
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240 views

DNS and transparent intercepting squid

I am building a transparent intercepting squid proxy in my home network. My network is 10.10.10.0/24 with a soho adsl router that is the DHCP server with a extra static route network addr 0.0.0.0 ...
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92 views

Ubunbtu 12.04 iptables error after upgrading kernel to 3.4

I been using Ubuntu 12.04 for well 3 years and using it with kernel 3.2. I decided to upgrade to kernel 3.4 because some freezing problems starting to occur more and more. Well the update went well. ...
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20 views

Single iptables on openwrt

I have a router with a fresh openwrt install and local network 192.168.5.0/24. There is a server SERV on 192.168.5.100 (HTTP and some other services). There is also a pptp-client tunnel (visible on ...
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194 views

Can I use iptables to temporarily block FTPS (TLS) server brute-force attempts?

There are couple of similar questions like this (e.g. http://serverfault.com/questions/200539/can-i-use-iptables-rate-limiting-to-temporarily-block-ftp-server-brute-force-att) , but I have a slightly ...
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126 views

Cannot ping virtual host behind NAT port forwarding

I'm creating network between real Windows 8.1 (R) and two virtual Debian 8 (V1, V2) using VM Ware. V1 has running Tomcat and should have access only to V2 and R should redirect V2 to V1. I used two ...
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165 views

What is the best way to limit the IP addresses which can be access from within a docker container?

I have an answer which will limit docker containers to only be able to access a single IP address outside the host. Using this iptables rule on the host: iptables -I FORWARD -i docker0 ! -d 8.8.8.8 ...
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75 views

Routing application traffic through interface, not receiving replying trafic

I'm trying to set up a Plex Media Server on a Arch server. However most of the time the server is connect to a VPN and I want the Plex traffic to be routed outside of the VPN interface, tun0 and ...
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214 views

Failover on voyage os using eth0 and ppp0 interfaces

Hi I am having problem for failover handling on voyage os. I have a system with eth0 and ppp0 interfaces where eth0 is primary and ppp0 is a secondary path for traffic. root@voyage:~# route -n ...
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36 views

Cannot access my port from other systems in same network

My machine is running in Red Hat Linux OS. I have setup a server using apache in port 8060. I am able to access in localhost but not is other systems for the same network. I am able to ping the ...
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48 views

Accessing Web UI with Spark1.3.1

I am currently building and deploying spark with standalone mode, including one master node and two worker nodes, on Google Container Cluster. For monitoring purpose (also connecting to master from ...
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213 views

Samba ports still closed even with iptables rules flushed and disabled

I’m trying to install Samba on a server running CentOS 6 with WHM/cPanel, and I’m having some trouble with ports. This is a brand new system as of yesterday, and I haven’t yet started locking down ...
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72 views

port forward in INPUT level

I want to change the destination port of the ipv6 packet in the INPUT level. So I tried to use ip6tables with nat in the INPUT level but seems this command does not work # ip6tables -t nat -I INPUT ...
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iptables directing traffic through vpn

Networking newbie. I have two interfaces on the host: eth0 and tun0 from my OpenVPN client. The IP addresses are: eth0 192.168.1.22 tun0 10.1.0.8 Question 1 For outgoing traffic by changing ...
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87 views

WordPress won't load unless iptables is disabled

I am running CentOS 6.6 using nginx. WordPress will not load unless iptables is disabled. I tried to add the 9000 port for fastcgi, but that did not work. I am guessing it has something to do with ...
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29 views

Manage NAT using a tool

I have a Raspberry Pi on which I had previously installed Raspbian and am now installing another version on again. It is mainly used to be a test maschine for small programs and primarily as a NAT ...
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36 views

iptables: Routing requests to localhost:8080 to google.com

I am trying a simple routing rule that would forward the requests to localhost:8080 to some external address (ex google). I added the following rule : sudo iptables -t nat -A PREROUTING -p tcp -d ...
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150 views

Tor Middlebox: How to check if there is a DNS leak?

I created a tor middlebox. Laptop plus WLAN. Creates a WLAN AP all traffic from that AP should be routed into tor. But I am not sure, if the DNS requests are not leaked. How can I check that? This ...
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2k views

ssh: connect to host * port 22: Connection timed out

I have CentOS 7 running on a VPS machine and after a computer restart, I could no longer SSH to it. $ ssh -v <IP> OpenSSH_6.6.1, OpenSSL 1.0.1e 11 Feb 2013 debug1: Reading configuration data ...
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92 views

iptables - How to mirror all ports from one IP to a single port on another IP

I would like to set up IP tables on my router to mirror traffic on all ports from 192.168.1.30 and send it to 192.168.1.10:5860 I think I need to combine the two commands below, but I'm at a loss. ...
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78 views

How to see who's blocking my internet connection? fail2ban?

I was just running apt-get dist-upgrade from a distant ssh console when I lost the connection. I would like to know which service blocked my connection. I know fail2ban is sometime a bit flaky, but ...
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296 views

Unable to Telnet to the Linux SUSE from windows with port 50000

Firewall has been disable at Linux SUSE server, port numbers from 50000:60020 has been enabled. I can able to ping the server able to telnet using IP. When I give port 50000 or 60000 in my telnet ...
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167 views

iptables TCP flags

I'm beginner with iptables and networking so please excuse me for such beginner questions. I found on the Internet part of filtering malformed packets: /usr/bin/sudo /sbin/iptables -A tcpchk -p tcp ...
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62 views

rsyslog loses messages from firewall

I am trying to make rsyslog to log messages from iptables MASQUERADE. I have iptables LOG rule in nat table and PREROUTING chain before the MASQUERADE rules. The actual iptables rules: iptables -t ...
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338 views

MaraDNS- Unable to forward DNS queries

I tried forwarding DNS queries to Google DNS but it is not working. Below is the content of my /etc/mararc file: csv2 = {} csv2["example.net."] = "db.example.net" csv2["google.com."] = ...
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500 views

iptables failed with “ iptables v1.4.21: Couldn't load match `-d':No such file or directory” message

I am running kernel 3.14.18 and using iptables 1.4.21, built with these options --static-enable --disable-shared. When I run this command: /sbin/iptables -A PREROUTING -m -d 127.3.0.2/24 -j DNAT ...
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861 views

How to allow only subnet for port with iptables

What i am trying to do is to DROP any packets to specific UDP port, except those one from my secured subnet 10.8.0.0/24. iptables -t nat -A --src 10.8.0.0/24 -p udp --destination-port 63210 -j ACCEPT ...
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96 views

Connectivity from different network segment

I have 3 machines 10.10.3.1 Windows # srv1 10.10.3.2 Lubuntu # srv2 10.10.200.1 Windows #cli1 network masks are 255.255.255.240 I can succesfully ping from cli1 to srv1 srv1 to srv2 srv2 to ...
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How to use iptables to allow traffic only through ONE SPECIFIC VPN

I'm trying to allow all traffic from my Banana PI running Lubuntu to only go to my LAN or otherwise through an VPN Server. I'm following this guide: ...
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1answer
246 views

Routing 6to4 packets through NAT

I have a linux router(dd-wrt w/o ipv6 module, no space for that) and a linux PC(Arch linux). I'm trying to setup my router to forward 6to4 packets(protocol 41) to my PC and setup the tunnel on it. ...
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155 views

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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256 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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784 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 ...