a technological barrier designed to prevent unauthorized or unwanted communications between computer networks or hosts

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110 views

How to config PORT KNOCKING on CSF ubuntu server and access it by linux?

I'm trying to run port knocking work on a CSF on a small VPS, i setup this: 1 - the result of csf first test ok 2 - TCP_IN = "53,80" TCP_OUT = "53,80,113,443" UDP_IN = "53" UDP_OUT = "53,113,123" ...
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2k views

UFW for OpenVPN

I want to configure ufw (uncomplicated firewall) for OpenVPN. Connections are only allowed through OpenVPN. Everything else should be blocked. So if OpenVPN is disconnected -> no internet! I found ...
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88 views

How do I find which OS layer (iptables, rp_filter, etc) is dropping a packet?

Let's say that I'm running a ping towards a machine and I see from tcpdump that the icmp echo reply is being received at the ethernet port but the ping program is not getting it. So I know that ...
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3k views

Refused connection of ssh

I installed openssh on my new Ubuntu14.04 server, turned on ssh, and enjoyed it after I finished installation. Every thing was fine; however, after just one night, I was blocked when using putty as ...
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401 views

UFW is DENY/DENY, but PACKETS are still getting out of my ethernet device. Why is this?

Hello, I have a question. I would like to use the UFW Ubuntu Firewall to lock both Input and Output completely from the server to ensure no packets are sent initially as a baseline. I enabled UFW, ...
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0answers
146 views

found someone lurking in my LAN, not sure what to do next

I have DD WRT router with internal numbers all falling within 192.168.1.0/24. I was looking on my firewall records this morning and found someone at 10.10.109.100 got blocked from accessing port 5353 ...
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295 views

How do we allow a certain mac address in a FORWARD chain through iptables?

I set the iptables rules in default. # IPTABLES IN DEFAULT iptables -P INPUT ACCEPT iptables -P OUTPUT ACCEPT iptables -P FORWARD DROP How will allow a certain mac address in a forward chain? I ...
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1k views

IPTABLES > MAC Filtering

I am newbie. I tried DHCP Mac filtering is not enough to secure our networks and I think iptables will... This is my concept: I set a new laboratory (LAB) network. My other network is connected to a ...
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196 views

How should I configure Ubuntu firewall?

Just discovered Gufw, and I'd like to set it up. But I haven't found any documentation telling me what I should/should not allow. I'd like to be able to use it but the only documentation on the web ...
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671 views

How I can connect the syslog-ng with a mysql database?

Hi guys I want to use a syslog-ng server for logging data from the firewall and I get Data from the Firewall in the file /var/firewall.log but now I want that the logs go to a database. For this I ...
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266 views

Why is SSH not accessible after installing KDE on Ubuntu Server?

I installed KDE onto my Ubuntu server, which is operating as a file server. It installed a firewall that wasn't there previously. I can't reach any of the services I had operating on the box now, ...
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19 views

regenerate iptables from “iptables -L”after disk failure

My system disk failed catastrophically. I've replaced and mostly restored the OS on a new disk but all I have for my iptables is the output from iptables -L. Is there a way to automatically recreate ...
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0answers
96 views

Why can't I connect to my localhost port from a remote computer?

I'm using link-grammar server to convert sentences into semantic graphs. It provides an API though a port to do the above process. It's configured to works through port 9000 of localhost. I used to ...
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0answers
27 views

UFW open range is still blocked

I have opened up a range of ports using UFW. The rules in question are shown below (output of sudo ufw status numbered). I have restarted UFW since I added the rule, yet in lnav I still see log ...
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26 views

Ubuntu as a bandwidth throttling box on windows network

I need to test the performance of some applications over different capacity connections (broadband, EFM, LAN extension etc). How would i configure an Ubuntu server to sit between the main network ...
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47 views

Transparent proxy listening on sub-interfaces

I have iptables and squid on the same box. HTTP traffic doesn't seem to be going through the transparent proxy when I change my rules on the filter table. What is the best point to filter http ...
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0answers
47 views

How to know the all minimum privileges that software needs?

I am using a VPS as a public proxy, and I have begun to realize that I must make my VPS more secure as I have seen in Securing Public Shadowsocks Server. Shadowsocks is a fast tunnel proxy that helps ...
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54 views

Is this ufw configuration correct?

I have to link my openstack private cloud on a cloud management platform online. The cloud location is on my private ip (192.168.0.9) , i can't use that ip since the platform need a public ip so i ...
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0answers
250 views

Why is ip forwarding not working in xubuntu 14?

I upgraded my gateway computer from xubuntu 12 to 14 and the computers on my home network lost their internet connection. I found that the upgrade had uninstalled my old firewall, Firestarter, and ...
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0answers
83 views

Can't Connect to Apache2 Server From External Device (in LAN) Nor From External IP?

I forwarded ports 80 and 443 for my apache 2 server. However, if I: try connecting to the server via external IP or try connecting to the server from a local device via my local ip, I cannot gain ...
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0answers
94 views

how to block all tcp and udp and other protocol and only allow layer 2 communication?

sudo ufw disable sudo ufw default deny sudo ufw allow XXXX sudo ufw enable Does sudo ufw disable block layer 2 by default? How to block all TCP, UDP and other protocols, so only layer 2 ...
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297 views

Why aren't these ufw rules working?

I'm trying to configure ufw to only allow connections to 3 ip addresses on my local network, and deny everything else. Here's the commands I'm using: yes | sudo ufw reset sudo ufw default deny sudo ...
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78 views

Ubuntu Randomly Rejecting Hosts

currently I am facing a very strange problem: my Ubuntu is randomly resetting connections and I have no clue why. /etc/hosts.deny is empty (resp. just the default file with comments only, that comes ...
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60 views

Connecting to Ubuntu host not possible

I have an Ubuntu-Host which is connected via wlan (and for testing to wired net) to a local net. This Ubuntu-Host is not reachable via network by any other clients on the same network. But: If I do a ...
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220 views

ufw is not working properly

I'm trying to enable ufw in remote ubuntu server. This server has two LXC container running. One container has nginx server running and I have hosted web application, right now every thing is working ...
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952 views

Ubuntu UFW init failure

I have some strange UFW behaviour. Whenever I install it cleanly and add some allowed ports to it (without restarting) it works great. But when I restart UFW or the whole server for the first time ...
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89 views

Dynamically Enable LAN traffic in Firewalld (using profiles in network-manager)

I am trying to use firewalld to allow dynamic profiles for different connections in Network Manager. When I'm at home, however, I would like to allow anything coming in on the LAN (local subnet). I ...
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0answers
104 views

Ubuntu server periodically unreachable

I have an Ubuntu Server 14.04 server running. The server has two NICs and acts as a NAT router, with the help of shorewall. Shorewall also acts as a plain firewall for blocking ports that I don't want ...
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194 views

Port forwarding out multiple VLAN interfaces that have same IP address

So I have an Ubuntu machine with multiple VLAN on an interface eth1 and each VLAN has the same IP address (172.16.0.2). I need to be able to simultaneously telnet into a rack of devices that are also ...
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89 views

Firewall rule to drop DOS attacks. What is wrong with my command?

I have a script like that : MAXREQ='cat /var/log/maxreq_tmp' DE=6 iptables -F iptables -I INPUT -p tcp -m state --state NEW -m recent --set iptables -I INPUT -p tcp -m state --state NEW -m recent ...
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0answers
8k views

ubuntu 14.04 default firewall rules

I would like to know exactly which scripts are responsible for default iptables rules (no ufw, no gufw) in Ubuntu Server 14.04. After fresh installation even with ufw disabled (by default) there are ...
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173 views

Configuring ufw and iPredator VPN

I am running a VPN via IPredator on Ubuntu 12.04 Desktop, which works perfectly, when ufw is disabled. When I enable ufw, I logically cannot establish a connection. IPredator states that I have to ...
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93 views

Allow users to access specified IPs only

I have a computer that offers both a VPN and a SSH server running three (separated) VPN networks. All users log into the server via ssh. However, I want that only certain users can communicate to ...
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0answers
3k views

Ubuntu 12.04 LTS - vsftpd problem. No connection. Connection refused

i have a problem with vsftpd server running on Ubuntu 12.04 LTS. Here is the configuration: ubuntu Server address - 192.168.5.100 router address - 192.168.5.1 roger/# grep -v "#" /etc/vsftpd.conf ...
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1k views

SSH connections rejected after UFW allow 22

I am trying to setup UFW on a 12.04 server. SSH works great with UFW off. Setting root@ugvps:~# ufw enable Firewall is active and enabled on system startup root@ugvps:~# ufw status Status: active ...
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528 views

UFW Firewall Rules, has a hole in it. Please help

Can someone please look at the below output for me. I have my UFW on deny/deny, and here are the rules. But if I leave my Ubuntu Server on, with a Windows XP VM, and let Instant Messenger run in the ...
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403 views

New Server - apache will not serve outside LAN

New server, running well 12.04 LTS on HP ML350. Apache = great, inside our LAN. Apache = timeout, from WAN (NAT forwarded from firewall). I have cleared all Iptables, read & checked every ...
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106 views

Is there a firewall that blocks a process and shows a dialog with buttons Allow, Drop, Disable?

Currently I use ufw and Firestarter, and I'm just learning how to use a firewall. When I used windows there were a couple of firewalls that could block a process which tried to establish connection ...
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930 views

How to change Port 27000 from filtered to open status

In my ubuntu box I am running flexlm licensing software on port 27000 and I am able to pull the license from the this port to run the simulation software locally. I am also trying to run the same ...
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0answers
269 views

ssh client times out to some servers, works on others

I have a strange problem and I'm not sure where to begin. My ssh client works on some servers but times out on others. Obviously, I checked that the servers are accessible via ssh from other ...
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0answers
15 views

Webmin Linux Firewall NAT and Packet Filtering

Can someone explain to me the difference between these two? Like in NAT and Packet Filtering there are rules for both incoming and outgoing packets. I do not really understand their differences. What ...
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0answers
24 views

Route packets between 3 subnets (nics) on same server

I have 3 subnets on my one server which acts as the router/gateway (10.1.10.0, 172.16.1.0, 172.16.2.0). All three subnets are assigned to their own NICs on the server. eth0 (10.x.x.x) is my ...
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0answers
21 views

Iptable rules filtering from ip address to interface

By default I have an implicit deny on my ubuntu firewall but I want to make the ip address 10.1.10.201 have a few privileges. I want it to have ssh and telnet capabilities to contact the external ...
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0answers
14 views

Openssh no port truly open

On Ubuntu 14.04lts, i try to install openssh-server (and client by the way) An apt-get install openssh-server openssh-client later I do not have change the sshd_config yet. The server is well ...
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23 views

Ubuntu server as dhcp router/firewall

I have properly configured the ubuntu server to have dhcp service and firewall rules. I also placed some firewall rules for testing. I just do not really know how to test it on lets say another ...
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10 views

Ubuntu UFW extending to whole network

UFW only allows the firewall to work within where it is installed. I was wondering if I made my ubuntu a wireless access point and other computer start connecting to it will UFW work for the other ...
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6 views

UFW keep close after running les than 24 hrs

I have tried to start the ufw ufw enable It it started. But it will stopped again in less than 24 hrs. How to make it keep running?
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25 views

cloud linux firewall port scan blocking my ubuntu desktop

My hosting provider's cloudlinux server is blocking my Ubuntu desktop every time I try to access the webserver. How do I find out what is causing this issue? Log shared with me.. May 28 13:49:32 ...
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21 views

UFW blocking 169.254.0.0 (link-local / apipa) addresses?

When using iftop on my wlan0 interface, there are a few link-local addresses connecting. How and where can I filter these connections? I have very specific UFW rules blocking 169.254.0.0/16, but I ...
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33 views

14.04 How to unblock UDP ports and UDP packets?

I'm use and Ubuntu Server, and I use it an Asterisk 11. But I have to unblocking the UDP Port 5089 and port for UDP packets in the range of 16384-16482. Also, I need to disable "SPI" in my firewall. ...