iptables allow creation of rules to define packet filtering behavior.

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conntrack in iptables not working [on hold]

I have tried to use conntrack in my iptables rules, however I keep getting an error. I've tried aminimal example with just one line and the error appears as well. admin@server:/home/admin/skrypty# ...
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2answers
62 views

Forward port 22 out a particular interface

The situation I'm in is where we have three separate interfaces on a particular machine. Each connected network only allows servers (by network-based routing/firewalling) to only offer particular ...
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0answers
24 views

how to route traffic on port to ip:port on linux?

I'm trying to route all traffic on port udp 5000 to udp 192.168.0.1:12333 with the following command: $ iptables -t nat -A PREROUTING -p udp -m udp --dport 5000 \ -j DNAT --to 192.168.0.1:12333 ...
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1answer
30 views

unable to initialize table filter

I have a firewall file saved in /etc/firewall.conf. Everything is ok, I can use it for iptables-restore /etc/firewall.conf with success. So, starting from this file, I created a PHP script(that runs ...
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3answers
15 views

Why did this iptables rule block my webserver?

I was setting up Mathematica on a remote server, and needed access to the UI. I set up VNC according to http://wiki.centos.org/HowTos/VNC-Server , and got it working, which involved making an ...
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27 views

VPN tunnel to two services on two servers?

I've got 2 CentOS 6.5 servers, each running one service: server A: 10.140.54.1/27 running service MySQL port 3306 server B: 10.140.54.2/27 running service httpd port 443 Server B's httpd service ...
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0answers
12 views

iptables: can't open tcp port

I'm running a Raspberry PI B+: Linux pi 3.12.28+ #709 PREEMPT Mon Sep 8 15:28:00 BST 2014 armv6l GNU/Linux The Raspberry is connect via lan (dhcp. ip: 192.168.78.29) to the local network. I'm trying ...
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24 views

Transparent proxy to other IP of thousand ports

I was bought a service that only allow a IP, the IP that i say, only one, but I need use this from more IP's. I think that I can install in this computer a system to do a transparent proxy for ...
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0answers
23 views

Server sending keep alive timeout probe despite timing out?

I am monitoring my firewall egress log and found the following outgoing connections that seem to originate from my server: Nov 14 09:56:48 DST=a.b.167.208 TTL=64 SPT=80 DPT=25960 Nov 14 09:48:48 ...
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23 views

Port randomly closing (iptables)

I'm running CentOS 6.5 on a VPS and one of the services I have running is murmur/mumble (A voip application). The issue I'm having is that the port clients connect on will be open when I initially ...
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8 views

iptables packet header capture and compare

We are using multicast program to listen up multicast data from our provider, there are couple cases where the multicast having issue: 1. their server hang, hence no multicast data received from our ...
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23 views

how to open up socks/SSH on different network interfaces?

iptables -A PREROUTING -i usb0 -t mangle -p tcp --dport 8080 -j MARK --set-mark 1 iptables -L Chain INPUT (policy ACCEPT) target prot opt source destination Chain ...
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1answer
54 views

can not telnet to a server connection refuse

I have two server with these specifications: IP address: 192.168.1.94 IP address: 192.168.1.221 I want to telnet to the first one from the second one (to port 5029) but I get this error: ...
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0answers
70 views

How to route pakets from an aliased interface towards a gateway?

I'm having trouble setting up the following: Router IP: 192.168.1.1 PC Eth0 - 192.168.1.104 Eth0:1 - 10.0.0.1 (must be an alias) Besides ip_forward enabled, what should I add to iptables rules, so ...
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3answers
86 views

Bridge/Router with custom logic

I've a Linux box with 3 network adapaters, which I'd like to configure as follow: Adapter A is connected to computer A Adapter B is connected to computer B Adapter C is connected to the Internet. ...
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0answers
25 views

Forwarding DNS traffic for specific domain

I'm trying to control which IP address I use for DNS based on the domain string. I'm on Fedora with firewalld and have tried the command: firewall-cmd --direct --add-rule ipv4 filter PREROUTING 0 -t ...
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1answer
44 views

iptables NAT on Debian openvz

So i want to create a nat rule for an openVPN server. After getting trouble with the TAP/TUN Devices, it's finally working i think. Now i have to make a nat rule like so : >iptables -t nat -A ...
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1answer
41 views

How does a transparent SOCKS proxy know which destination IP to use?

There are two SOCKS proxies that I know about that support transparent proxying for any outgoing TCP connection: Tor and redsocks. Unlike HTTP proxies, these SOCKS proxies can transparently proxy any ...
2
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1answer
48 views

iptables, what is truly open?

We have an RSA appliance, I've reviewed the firewall rules on this appliance to determine what ports are enabled. To me, it looks like its wide open; but the vendor states that I am wrong about this, ...
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1answer
15 views

How to wrap iptables commands around Ruby webrick server going up and down in a single command/script?

I would like to use this Ruby WEBrick server solution for on-demand showcasing of some random web pages. So I set up some forwarding exception on my adsl modem local web interface(192.168.2.1). Then ...
2
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1answer
82 views

How to completely block a website like Facebook?

I'm trying to block Facebook access from my home system (Ubuntu). I could add facebook.com to /etc/hosts, but that would only prevent accessing facebook.com. There are many other ways I could use ...
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2answers
57 views

Is there a specific reason why iptables would return an exit code of 3 (instead of 1?) when executed without sufficient privileges?

I simply forgot to use sudo: usr@arch ~[0] $ iptables -L iptables v1.4.21: can't initialize iptables table `filter': Permission denied (you must be root) Perhaps iptables or your kernel needs to be ...
4
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1answer
38 views

Dovecot/Postfix mail server replies to [SYN] with [RST, ACK] when user attempts to connect (POP3). Likely iptables?

Currently I'm trying to troubleshoot an e-mail server that will allow users to send e-mail, but not log in to the server (POP3) or receive e-mail using their Outlook clients. Previously this was ...
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0answers
15 views

Making sense of this iptables http proxy config

I've never touched iptables before and I'm trying to understand exactly what these three lines do. I have ip_forward switched on and I know the end effect is that all traffic on eth0 is forwarded ...
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22 views

iptables rate limit error

This is on centos 6.5, I want to limit number of maximum connections using iptables: iptables -A INPUT -p tcp --syn --dport 80 -m connlimit --connlimit-above 15 --connlimit-mask 32 -j REJECT ...
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1answer
34 views

Can I forward all traffic on a port to a complete different IP address?

Here's my situation. I own a VPS that provides 3 public IPs / public interfaces. let's call these IP address V1 (on eth1), V2(on eth2) and V3 (on eth3) At home, I have a router. The home WAN IP is H. ...
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1answer
18 views

iptables fowarding rules

I have an iptables rule in the FORWARD section that looks like this: 17 0 0 CONFIRMED tcp -- * * 0.0.0.0/0 172.16.30.240 tcp spt:587 dpt:587 ctorigdst ...
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1answer
24 views

What means the numbers besides my default policy chain rules?

I am investigating a potential security issue in one of my system. My firewall tables currently look as, :INPUT ACCEPT [527:57388] :FORWARD ACCEPT [0:0] :OUTPUT ACCEPT [189:35832] -A INPUT -p tcp -m ...
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0answers
31 views

Only allow http and SSH traffic

I ran the below. What I expected was to be able to browse websites without issues. No sites work and I have no idea what. When I executed iptables -P OUTPUT ACCEPT it works so I'm assuming I missed an ...
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0answers
24 views

IPTable rules for transparent outbound proxy

I've recently installed MITMProxy (similar to Squid) which I'm currently using to route outbound HTTP requests from my Ubuntu machine to another server (adding a header along the way). When I use ...
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0answers
49 views

Setting up a 802.11s mesh network for mobile devices to communicate with a wired server

I'm in the process of developing an android app that maintains a device's connectivity to a linux-based WiFi mesh network, and periodically sends status information (GPS, battery life, etc.) to a ...
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2answers
60 views

set connection limit via iptables

I want to limit the IP traffic of an application (AceStream Player). The problem is that I get disconnected, if too many IP connections are established. Does anyone know, how to use iptables to limit ...
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0answers
37 views

CentOS IPTABLES how to block requests from router

I have a CentOS machine that I use in private LAN for development and as file server. I did the following setting to allow httpd, GlassFish, Samba and SSH. Chain INPUT (policy ACCEPT 0 packets, 0 ...
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3answers
207 views

How to get all IPtables rules

I'm trying to see a list of all the rules in IPtables in a Debian 7 server. when I try: iptables -L -n I only get one rule (which I entered 5 minutes ago). I have many others, for port 80, mysql ...
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2answers
122 views

set packet rate limit via iptables

I have a packet rate limit (max. 10 per seconds) which is set by my internet provider. This is a problem if I want to use the AceStream player, because if I exceed the limit I get disconnected. How ...
0
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1answer
42 views

Isolate subnets on the same interface

I need to isolate Subnets on a linux machine CentOS that act as gateway. I have the following scenario. CentOS eth0 pub ip addres eth0.1 192.168.1.1 eth0.2 192.168.2.1 Now eth0.1 and eth0.2 can ...
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1answer
104 views

Fail2ban consuming lot of bandwith

I have a raspberry pi on which I have a nginx and a ssh server, I have installed iptables and fail2ban in order to limit the attempts of ssh connection. The problem is that it seems that fail2ban ...
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0answers
23 views

NAT-T set up using 3 linux machines

I am trying to have a simple NAT-T setup using 3 linux machines. Linux1 Linux2(NATdevice) Linux3 (eth0) 192.168.1.51 <--->(eth1)192.168.1.80 & ...
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0answers
59 views

UFW before rules for VPN forwarding

I'm trying to setup an OpenVPN server on Debian 7, following this guide: How to install and set-up OpenVPN in Debian 7 (Wheezy) In step 15 I have to setup forwarding and IPtables rules. I prefer to ...
0
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1answer
112 views

IPTABLES comment: No chain/target/match by that name

Faced with error when adding new rule with 'comment': # iptables -I INPUT 1 --source 66.***.***.78 -j REJECT -m comment --comment "Some" iptables: No chain/target/match by that name. Without ...
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0answers
68 views

Routing incoming source IP traffic to a loopback IP issue

I'm wanting to accomplish the following: I have a BIND DNS server setup where it is listening on ANY address and also listening in a BIND config ACL on 127.0.1.1. If there is another way where you ...
0
votes
1answer
57 views

IPtables don't block IP

I'm running Postfix SMTP server. Some hosts trying to connect with wrong passwords. warning: s15393678.onlinehome-server.com[74.208.17.126]: SASL LOGIN authentication failed: I'm adding iptables ...
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0answers
10 views

iptables/netfilter behavior if DNAT changes mid-connection

I'm planning to leverage iptables to act as a 'poor-man's active/passive load balancer'. The plan is to have a pair of these rules: -t nat -A PREROUTING -d 10.1.2.3/32 -m condition --condition ...
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0answers
26 views

Which tool is used to create firewall rules on Fedora 20? [closed]

What is a recommended way to set up firewall rules on Fedora 20/Centos 7/RHEL 7 currently? I know about relatively new replacement of itpables service by firewalld service. Which command-line user ...
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1answer
45 views

How to measure iptables load?

I have added about 3500 IP addresses to iptables using ufw on a Debian 7 and I am wondering if this has any impact on the performance of my server. How can I measure that?
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1answer
78 views

CentOS 7 iptables problems and doubts?

I have a CentOS 7 image on VM VirtualBox (bridged Ethernet with static IP) I was trying to set iptables filter table but I have the following problems: Whatever I did to open Apache on port 80 ...
1
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1answer
292 views

Whitelist IP's in CentOS 7

I want to setup CentOS 7 firewall such that, all the incoming requests will be blocked except from the originating IP's that I whitelist. And for the Whitelist IP's all the ports should be accessible. ...
0
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0answers
47 views

How to bridge the eth0 (ethernet) and eth1 (WiFi_Ap)?

I am in the WiFi test embedded board. The ethernet port eth0 is connected to the Internet. The interface eth1 is caused due to the WiFi chip. The Access Point can be used as a WiFi eth1 is. We use the ...
0
votes
1answer
39 views

Allowing web server communication in Linux firewall

I have a unique situation. Let's say my webserver ( e.g. 10.0.0.2) is connected to eth0 of my firewall (gw 10.0.0.1). A local network (192.168.0.0/24) is also connected to eth1 (192.168.0.1/24) of my ...
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20 views

What is the point of the second route lookup after OUTPUT?

According to the packet path diagram, and its description: Table 6-2. Source local host (our own machine) [...] Routing decision, since the previous mangle and nat changes may have ...