A firewall is a program that controls the incoming and outgoing network traffic on a system. Use this tag for all questions related to firewall configuration and operation.

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'iptables -a' just hangs and never returns? [on hold]

I'd like to redirect requests in on port 80 to a service I already have running on port 8443. I swear I've used this command before on other systems and it's worked: sudo iptables -A PREROUTING -t ...
3
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1answer
64 views

Block all internet connections unless connected to OpenVPN server

I want to block all internet connections unless I'm connected to my OpenVPN. Now of course, I need to allow connection to the VPN server. Can this be done, by allowing out/in traffic to/from the VPN ...
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0answers
24 views

Iptables - Forwarding in CentOS - Maintain Source Address [closed]

We have a CentOS 6.5 server setup to forward traffic using iptables - Question: How do we have the client IPs maintained when they are passing their syslog data through the forwarder to our endpoint ...
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1answer
25 views

Debian Jessie server has no internet access

I have a server running Debian 8 Jessie that constantly loses it's internet access for seemingly no reason. The server has two wired connections, the internet access is on eth0 and the internal ...
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1answer
47 views

UFW rules to allow specific behaviour

I'm new to UFW. One of our servers were compromised and I had to immediately: Deny all inbound. Deny all outbound. Allow all SSH. Allow outbound DNS. Allow Git clone, push, pull, etc. Allow only ...
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2answers
48 views

Block Internet access, but not network access for a user

Hi I would like to block one user on all of the linux machines (Debian Wheezy) from being able to surf the internet, chat and email. However they are using linux based Rip stations for large format ...
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1answer
16 views

UFW: Allow traffic only from a dynamic IP on its last 2 elements

I am trying to setup the following rule on ufw: ufw allow from 217.87.123.0/24 So to allow incoming connections from all 217.87.123.* addresses. The problem is that my IP does not always start ...
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1answer
22 views

IP tables - how to configure connections into my compuer

I have a problem with following thing: Foreign connection is connection initialized not by my computer. I would like to accept only foreign connection such that port is 22 or from interval [1000, ...
4
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1answer
35 views

Is libvirt dnsmasq exposed to the network, if I run Fedora without a firewall?

There's this nice saying from Ubuntu: no open ports on the default install. Other Linux OS's look the same, including Fedora. No-one wants to worry about firewalls, if they don't need to. Yuck, ...
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33 views

Linux: Building our own firewall box?

I'm actually on AWS Cloud, but sick of their limitations of IP Blocking feature given in Network ACLs there. Because Network ACLs can "BLOCK" by IP but they have rule limitations. So i came to think ...
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0answers
11 views

What puts TCPMSS in iptables?

I used to have (well, I still sort of do) have a script that expects: -A FORWARD -p tcp -m tcp --tcp-flags SYN,RST SYN -j TCPMSS --clamp-mss-to-pmtu to have been entered in to iptables ahead of my ...
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1answer
36 views

Firewalling Samba

at the moment I'm trying to implement the firewall for my linux file server. Everything is working as expected except form the samba server. I have searched through the internet already but non of the ...
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0answers
42 views

IPTables if more than 30 connection in 1 minute ban IP for 1 hour?

I am trying to setup a firewall that limits to 3 connections per IP and also ban the IP for an hour if > 30 connection attempts in one minute. Is this all possible with iptables? So far I have only ...
3
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0answers
23 views

connlimit counters start over after iptables restored

I have a connlimit rule in iptables that allow only 5 connection to port 80. iptables -A FORWARD -p tcp -m tcp --syn --dport 80 -m connlimit --connlimit-above 5 --connlimit-saddr -j DROP This ...
0
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1answer
23 views

Can Shorewall be used on VyOS?

Will VyOS still work right if I install Shorewall-lite on it? Shorewall seems like an easier way to setup a network, but VyOS seems pretty great for day-to-day management of a router / firewall. So ...
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0answers
108 views

string matching not working in iptables

We have a RHEL 6.7 DNS server and we are trying to discard packets that contain certain domains. For example, one of our DNS servers was involved in a random subdomain attack, where external hosts or ...
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1answer
14 views

ip_conntrack_max test not working

I am trying to do some ip_conntrack_max kernel parameter testing, but somehow its not working. -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT I have set following value to see its filling ...
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0answers
8 views

how to safely increate ip_conntrack value

How do i calculate how much memory my single ip_conntrack connection will eat? I am planning to increate ip_conntrack on system but i want to be careful to not overcommit number. Is that any basic ...
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2answers
46 views

Is UFW behind a firewall(ed) gateway router necessary

Is it really necessary to run UFW behind my Gateway Router which already has Firewall/Port rules? In this example, I am discussing running UFW on an Internet Accessible (Linux) Server that is behind ...
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0answers
196 views

pfsense: squid transparent proxy not working in bridge mode

I have installed the latest version of pfsense. I have setup it up in bridge mode after creating a rule any for lan and wan respectively. I have setup the squid on transparent proxy mode with ssl ...
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1answer
49 views

ipset v4.5: Unknown set type

I compiled ipset on CentOS5 32bit machine and i am getting weird errors My kernel: [root@localhost ipset-4.5]# uname -a Linux localhost.localdomain 2.6.18-400.1.1.el5 #1 SMP Thu Dec 18 00:58:32 EST ...
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1answer
19 views

In what order are the rules handled in the Linux Firewall Module in webmin?

If I'm not mistaken it's top to bottom correct? And the catch-all default action at the end is to just drop any packets that don't match the rules above. Should I be logging the dropped packets as ...
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1answer
56 views

ufw allow ssh - and then connection gets lost

I'm trying to set up a debian server in the cloud, over SSH. I log in using a key. After the initial startup I want to set UFW: apt-get install ufw ufw allow ssh ufw enable This is how I've done ...
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1answer
23 views

Basic Hosting Postgresql in Virtualbox + Ubuntu 14.04

I have configured Postgres to accept network connections from anywhere: In pg_hga.conf: host all all 0.0.0.0/0 md5 In postgresql.conf: listen_addresses = ...
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1answer
47 views

i have problem with firewall this question like this: [closed]

configure packet filtering firewall to allow DNS, HTTPS from outside to server configure PAT for HTTP using port 8080 from outside to server deny all other services and i have problem like this ...
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1answer
194 views

Connection refused on port 8081 using curl

I have two CentOS 7 boxes, called Turbo and Demo. I started a daemon/service on the first one, Turbo, and wish to call the service from the second one, Demo. I started the service to monitor port ...
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1answer
55 views

Iptables: does dropping UDP packets take place in the user-space or kernel-space?

I know that Iptables is a user-space module, I also read it "configures" kernel modules to do big part of the filtering. So my question is, if I add a rule to allow only TCP:443 packets, would this be ...
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20 views

Debian 8 and few questions about Graphical Firewall?

So I have installed Debian 8 today and so far so good. What I want to achieve now is to install firewall but can't find Firestarter in repos (discontinued ?). So I have installed a GUFW and set it up ...
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12 views

Ubuntu Network Crashed?

So I have a server from ovh. When I was messing with the network I went to flush iptables and reload the network, and well it crashed all of the ports. So I thought I just need to reboot the server, ...
0
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1answer
17 views

How to customize Shorewall firewall logs

I am using Fedora 13 machine with shorewall installed. shorewall 4.6.6-RC1 iptables v1.4.7 Below is log format by shorewall: Oct 23 05:28:17 localhost kernel: shorewall:LAN-LAN:ACCEPT:IN= OUT=lo ...
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30 views

How can I improve this script to install pptpd & csf on a Centos 6.5 openvz box?

I'm working on a script to ease the deployment of pptpd and csf on openvz boxes. Here's what I've got so far: echo "Installing epel repository, wget, and bind-utils..." yum -y install epel* yum -y ...
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1answer
25 views

iptables logging for all except ICMP

I have iptables firewalls and its logging for all DROP packets or Deny. I want to tell it to no LOG any packet for ICMP protocol. How do i tell that *filter :INPUT DROP [0:0] :FORWARD ACCEPT [0:0] ...
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1answer
17 views

firewall configuration to prevent a server-client malware connection

can i prevent a malware to connect on my pc simply setting ''incoming traffic to deny'' and allowing only outgoing traffic? I red that a malware could use the port knoking tecnique, but with a GUI ...
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0answers
44 views

How to Limit the hit-rate of connection for “X-Forwarded-for” IPs?

I have Apache, which is behind the Amazon ELB which forwards the IPs as in "X-Forwarded-for" header. I found some articles around to do the hitrate limitation but i doubt they are all for real IPs, ...
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0answers
29 views

Limiting number of simultaneous connections system-wide?

In my dormintory, I've got a not-so-nice networking environment, in which I'm identified only by mac-address of my ethernet card. In said environments, some limits of simultaneous opened connections ...
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0answers
52 views

UFW Preventing Web Browsing

I have the following rule set configured using UFW on Debian Jessie 8.2.0: Status: active Logging: on (low) Default: deny (incoming), deny (outgoing) New profiles: skip To ...
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2answers
99 views

Route incoming and outgoing on same interface

My router currently provides the NAT to all the PCs and the Ubuntu desktop (with some server functions) in the network. I want to use the Ubuntu system as a proper firewall, but it only has one ...
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1answer
39 views

How do I configure my server to stay hidden unless it receives correct password?

The server is supposed to silently ignore any requests (including ping) unless it receives correct credentials with initial request. Nobody else can tell that the host even exists. I am talking about ...
0
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1answer
181 views

Firewall blocking SSH/SFTP connections. How to cheat it?

Hi folks (sorry for the bad english) I'm a college student, and I live in the student's house of my university. I study computer science, and there we have the right to a space in a nfs server to ...
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0answers
21 views

how to set the ip tables for two vpns connected togheter

Immagine this scenario: two vpn. The first vpn is on the host sistem and the second is on a virtual machine. I want to connect to the first vpn and then to the second vpn on the VM, so i set ...
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0answers
25 views

Forward public network around current network

For the purposes of this discussion, I have a very current always-on linux machine with two nics: wifi0 eth0 A very crude diagram of my desired configuration looks like this: ...
2
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1answer
69 views

how to set ufw firewall/iptable rules for a VPN Server to be explicit in allowing certain connections?

I want to connect to a VPN. I want to enable ufw firewall or iptables so that there is no connection that goes out of the VPN tunnel or that comes in (except that for VPN server). Could you ...
0
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2answers
42 views

Domain only for web server

I have a domain which i want to point to my server. But i don't want to allow other people to use this domain to reach the server, only specific ports on the server (web server, so port 80). So if ...
2
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2answers
70 views

Best practises: Applying iptables firewall rules for SSH

I need to add some firewall rules in our QA environment using iptables. I have to do the changes remotely . Some of the changes also include disabling SSH for few Networks . What are best practices ...
2
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1answer
394 views

Why does iptables accept packets on a given port, when it is closed?

Here is my situation. I have a public address on my router and have manually forwarded a given port for torrenting, so not via UPnP, that is disabled both in the router and the application. It works ...
0
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1answer
128 views

How to set up a clear SuSE-Firewall?

I’m doing some rules in a machine with the firewall disabled, but when I run rcSuSEfirewall2 a lot of rules and policies are applyed by default: iptables -L Chain INPUT (policy DROP) target prot ...
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1answer
162 views

ufw won't allow connections to port 5432

I've installed Postgresql 9.4 on Ubuntu Trusty from the PGDG ppa. I've created a database and set it listen-addresses to '*'. I've made an entry in the pg_hba.conf file. I can connect locally with no ...
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0answers
21 views

Separation between the User machine and Server machine by another linux for monitoring

I am planning to have three virtual machines with virtual box (m1, m2,m3). I already installed on m1 = Windows XP Home Edition, and on m2 = LUbuntu 15. The big picture is this : m1 : a user m2 : ...
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1answer
38 views

Firewall Rule Testing - telnet failing

I am testing firewall rules but the telnet is failing. The firewallrules have been implemented but the target server is not listening on the servers. How can I enable the target server ports to ...
0
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1answer
175 views

iptables - how to drop protocols [closed]

I have the desktop-server Debian Jessie machine running for testing purposes just for 19 hours now. I have already set a few rules as you can see above. But I am not really into networking. So it ...