iptables allow creation of rules to define packet filtering behavior.

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57 views

What considerations would I need when configuring iptables?

Synopsis I am looking at learning more about Server Administration. I have been running my own web server for a few years although many things were set-up by my friend and now I wish to learn more ...
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1answer
88 views

How to combine connlimit with IP sets?

connlimit lets me limit the number of connections per client/service. How would I go about to combine such a rule with the IP sets available in more recent versions of the Linux kernel and netfilter?
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60 views

Connection lost to VPS While using iptables by default policy as DROP for INPUT, OUTPUT, FORWARD

I'am using iptables in many server's but now stuck with this issue while using default Policy as DROP. Here is my rules which i have used in VPS, Tried many time's everything seems fine but VPS ...
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1answer
26 views

How to carry a string over from one chain to another in iptables?

Here's what I'd like to do. In my rule file (which I use with iptables-restore) I have (with limits removed): -4 -A LOGDROP -j LOG --log-prefix "ipt:4:drop " -6 -A LOGDROP -j LOG --log-prefix ...
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0answers
97 views

iptables: using “conntrack” and “recent” modules to block unsolicited packets

When I only allow RELATED and ESTABLISHED packets, and DROP everything else, my firewall rules work perfectly and I have no problems: ### VARIANT A -A INPUT -i wlan0 -m conntrack --ctstate ...
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1answer
46 views

Observing ping replies under DNAT

I'm confused while trying to understand the DNAT mechanism under below circumstance. My understanding: DNAT = Destination Network Address Translation: Functionality which translates the destination ...
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4answers
91 views

How can I lock myself out of a linux box with iptables?

In the Securing Debian Howto I read (about iptables): The tools can easily be misused, causing enormous amounts of grief by completely crippling network access to a system. It is not terribly ...
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1answer
86 views

How do I apply iptables SNAT to packets bound for localhost (INPUT chain)?

I'm setting up a host that has two routes to the public internet: one via my run-of-the-mill home gateway router, the other via a gateway router on a semi-private network (AMPRNet on 44.0.0.0/8). Most ...
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1answer
114 views

BIND/DNSMASQ query hanging on ubuntu server 14.04.1

I'm testing out a BIND and DNSMASQ configuration on my VPS. When I run a program which submits a bunch of queries (around 10-20 per second) my DNS replies stop coming back for a random amount of time. ...
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1answer
70 views

iptables rules for machine running as openvpn server

I set up an older laptop as an OpenVPN server for my home network (and a dwarffortress server, but that's beside the point). This is the first time I've set something like this up - I wanted a secure ...
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0answers
110 views

Redirecting all non-local traffic from specific ip to external proxy

I currently have a squid proxy running on an external server (outside the LAN, with a public IP). I would like to route all non-local traffic from a specific device through it. That is, any requests ...
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2answers
134 views

Redirect outcomming traffic to local server

I have a Apache web server set which listens on port 4000 and I want to use this (local) server as a kind of proxy. The idea is to redirect all the local outcomming HTTP traffic (port 80) to my ...
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0answers
37 views

Strange cron behaviour

I have a script that reads a list of IPs from a file, compares with the existing ones in a chain, and adds recently added IPs in the file into that chain. Running the script manually (e.g., ./script) ...
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1answer
40 views

iptables routing through firewall

I have a httpd service running on server machine, I have a firewall and internet browser on desktop machine. On server I have a rule that only firewall can access to server: -A INPUT -m state ...
2
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1answer
150 views

iptables ruleset causes server to stop answering

I'm trying to configure my proxmox server's firewal and redirections. The aim is to block everything, open the necessary ports for basic services to work and, finally, redirect some ports to virtual ...
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0answers
87 views

Internet sharing disappears when either eth0 or wlan0 gets disconnected

I just got a RasPi B+ and I'm looking to replace the Windows PC that's doing the routing job. What I'm trying to do with the Pi is making it share the connection (wlan0) with another wifi router (via ...
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1answer
37 views

Does iptables protect from kernel vulnerabilities? [closed]

I read a lot of kernel vulnerabilities which are beyond my understanding. I would like to reduce the risk of an issue related to one. If I block everything other than SSH on a server, will this help ...
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1answer
134 views

how to make firewall changes permanent via firewall-cmd?

I am trying to open some ports in CentOS 7. I am able to open a port with the following command: firewall-cmd --direct --add-rule ipv4 filter IN_public_allow 0 -m tcp -p tcp --dport 7199 -j ACCEPT ...
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92 views

route gateway proxy traffic through different interface with identical upstream gateways

My question is similar to the below with a small caveat not answered by any of these threads: Output traffic on different interfaces based on destination port ...
2
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1answer
34 views

(S/D)NAT over NF hooks

Could someone help on explaining the advantage of iptables NAT over the netfilter hooks. Say suppose, instead of using NAT if we create custom kernel module to bind handler with netfilter for PRE/POST ...
2
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1answer
24 views

Make a request through vpn interface

I want to be able to make request through a specific network interface, like this: ping -I eth0.1 google.be ping -I eth0.2 google.be This example works on my multihomed OpenWRT router. I now want ...
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2answers
42 views

rc.local and networking start order

If I add iptables-restore to my /etc/rc.local script, will this be guaranteed to be executed before any networking is started by the OS? The alternative is that there will be a brief period where my ...
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0answers
82 views

Is iptables able to filter off UNREPLIED connections?

I am a using dd-wrt router and trying to get some per-user metrics, I was wondering about filtering only ESTABLISHED connections or include NEW and RELATED, I have read a lot about this last two, but ...
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1answer
42 views

iptables INPUT command

On a machine called ubuntu1, this is the iptables command: sudo iptables -A INPUT -p icmp -j DROP on the other computer (xp1) I can not ping the ubuntu1.So this is OK. But On ubuntu1 can ping xp1. ...
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1answer
262 views

Proxmox shows “Login failed, please try again” when I apply my iptables rules

I've just got a powerful dedicated server, and I'd like to virtualize it. The idea is to install Proxmox VE on the host and then create a VM for each use: one for my website, one for mi Git repo, and ...
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1answer
90 views

Minimize game server delay with iptables

I have a debian 7 server hosted by Google Cloud running a game server and a rails server. The rails server run on port 80 and the game server on port 8000. I wanna apply a network rule that allow ...
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1answer
265 views

record contents of packets dropped in iptables

I'm trying to find a way to record the entire contents of packets (possibly with tcpdump) that have been dropped according to rules in iptables. At present, I have a rule to log these packets (with a ...
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0answers
37 views

Initial iptable rule and knockd operation in vps

Today I launched a vps with Debian 7 x64 and started playing around with it. I installed xampp as well as knock daemon to get my hands dirty. So, all I wanted to do was to actually block all requests ...
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1answer
32 views

How to configure correctly iptables for run Maples with a blocked internet connection?

I would like to be able to run Maple with a blocked internet connection. For doing so I set my iptables by doing something like this for user joe: sudo iptables -A OUTPUT -m owner --uid-owner joe -j ...
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0answers
87 views

I Need Find A Mac Address from a client connected to my Teamspeak

I have a dedicated server and from it I am running a teamspeak 3 server. In teamspeak server there is a client who need to be banned. I have banned him from teamspeak but if you change your windows ...
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0answers
37 views

iptables rules to issue with tftp

My requirement is to add iptables rules in such a to allow tftp traffic(as a client) and drop everything else. And in fact using the iptc library programmatically using C code. To start with I tried ...
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2answers
50 views

iptables is ignoring rules?

I've found some strange traffic through tcpdump (traffic is ongoing always): 13:00:13.203754 IP 1.2.3.4.1028 > 188.113.188.16.56881: UDP, length 103 13:00:13.204396 IP 1.2.3.4.1028 > ...
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176 views

Slackware internet gateway with iptables / poor browsing performance

I am running a dual core headless computer as internet gateway via pppoe with two NICs. eth1 (internet interface) no ip, no dhcp eth0 (LAN interface) - 192.168.0.100 static ppp0 - dynamic ip ...
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77 views

Using a VPN client as a VPN gateway

I would like host 1 to use host 2 as a gateway to the remote host 3. I have scoured the web looking for a solution, but it doesn't seem to work for me. VPN client software is ike (shrewSoft VPN) is ...
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53 views

Set user-wide network proxy settings on Ubuntu (without restart)

Is there any reliable way to set proxy settings user-wide for all traffic on Ubuntu? As far I'm using {http|https|ftp}_proxy variables in /home/$USER/.bashrc which is nice but there's some issues: ...
3
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0answers
104 views

Route VPN traffic through different proxies

I want to setup VPN server and route (based on my routing algorithm) all traffic through different proxy servers. Let's say I have one host, with many users, connected to my VPN. I want to route all ...
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0answers
22 views

iptables and applications

I'm trying to set up a little download box. I currently have pyLoadCore, Transmission-daemon and openvpn all running on raspbian (raspberry pi running headless). My problem arises when I have openvpn ...
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1answer
34 views

Iptable forward interfaces for gateway machine

I have two Ethernet interface being configured to use as system gateway ex: eth1: 10.10.1.0 eth2: 10.10.2.0 I want to forward all the packets which are coming to the 10.10.2.0 gateway contacting ...
0
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1answer
276 views

viewing firewalld logs via remote login to CentOS 7 server

I have firewalld installed in a remote CentOS server. When I log into the server over the internet as root, I type the following command to access the firewalld logs: journalctl ...
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0answers
591 views

Network firewall on CentOS, host cannot be resolved?

I have a centos machine and I am trying install some dependencies using yum. When I do this I keep getting a message saying the host cannot be resolved. I was told the previous person that used the ...
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145 views

iptables IP address (source and destination IP address) mangling

I tried to understand the concept of iptables mangling part, but somehow failed to understand the IP header manipulative section. For example: Below is the system scenario which I'm trying to ...
0
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1answer
131 views

conntrack in iptables not working [closed]

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
136 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
151 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 ...
1
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1answer
473 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
31 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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0answers
41 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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120 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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0answers
62 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 ...
3
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1answer
103 views

Why are these connections not classified as “established” under conntrack?

I have the following rule for iptables: -A OUTPUT -m conntrack --ctstate ESTABLISHED -j ACCEPT such that outgoing connections not classified as established will be logged. Occasionally, the ...