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

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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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103 views

Unable to connect to Chromecast

I seem to be having a problem connecting to Chromecast from Ubuntu. Unlike the question How can I use Chromecast, the issue doesn't seem to be firewall related. I have already tried opening the ports ...
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120 views

iptables rules keep showing up

I just installed an ubuntu precise server, after a few weird communications issues I checked the iptables list and found: Chain INPUT (policy DROP) target prot opt source ...
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42 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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3answers
380 views

14.04 missing “/etc/init.d/ufw”? my firewall never auto starts

I need to know how to fix the missing "/etc/init.d/ufw" file, is it some package or some command? I used the gufw to enable it, but on reboot my firewall was still off... I created a symlink ...
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1answer
300 views

Ubuntu 14.04 denying incoming access

I just install a Counter-Strike: Source Dedicated Server on my Ubuntu 14.04 Desktop amd64 and I'm having trouble to allow incoming access to this server from the internet. I did a port forwarding on ...
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1answer
1k views

Iptables rules no longer honored

I installed Ubuntu Server 64-bit 14.04 a week ago. It worked fine for one to several days, then out of the blue, iptables became meaningless (I noticed FTP and such are down ). Only ports 22, 25 & ...
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2answers
156 views

What is MASQUERADE in the context of iptables?

In Iptables many times I see the target MASQUERADE. What is that. I searched and find lots of things. But I need some one explain me what MASQUERADE is in a so easy way? **If you bring an example ...
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82 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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62 views

Ubuntu 13.10 allows connections from LAN but not from outside LAN

SSH ports configured to all 22 and another one. I can connect from another Linux/Windows workstations on my home LAN no problem. Same thing for nomachines nx server. Teamviewer connects with no ...
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413 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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1answer
146 views

configuration for ufw to allow upnp between desktop and xbox360

I am really stuck with this question. I am using Ubuntu 14.04 I cannot enable UFW to allow a connection between my desktop and Xbox 360 stream media when UFW is enbaled. The connection and streaming ...
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1answer
99 views

How to install GNU Parallel in Ubuntu 12.04 with my firewall?

I am running Ubuntu 12.04 in our production system. How do I install GNU Parallel in my system? My system is behind a firewall so it will block any download from external connection.
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1answer
690 views

Firewall rules for transmission

I have transmission installed, which listens on the default port 51413. I have tried opening everything for this port. iptables: Chain INPUT (policy ACCEPT) target prot opt source ...
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0answers
60 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
63 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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1answer
52 views

iptables ruleset blocking all network activity?

I've gone through numerous trial and error to recently discover that my iptables result is the culprit of blocking all LAN and WAN activity. I know this, because if I comment out the last line in my ...
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1answer
230 views

Docker is blocked by UFW

I have problem with Docker network in ubuntu 14.04. I have installed Docker.io from official repo and I've added DEFAULT_FORWARD_POLICY="ACCEPT" to /etc/default/ufw but my Docker containers still ...
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1answer
703 views

Where to get nftables?

As far as I understand the kernel facility nftables exists in the kernel that comes with Ubuntu 14.04. As is proven by the following two commands: # grep -E '(NF_TABLES|NFT_)' /boot/config-$(uname ...
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141 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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18 views

Ubuntu 12.10 won't boot: FIREWALL: IN=wlan0 OUT= MAC=… SRC=… DST=… LEN=68 TOS=0x00 PREC=0x00

My 12.10 won't boot up suddenly. And it just stucks at the following screens: I've tried googling "Ubuntu 12.10 boot stuck at FIREWALL ...", but had no luck (most of the results are not ...
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0answers
53 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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2answers
555 views

UFW rules don't work with docker

I have a 12.04.4 server, and I have enabled ufw, and have tried to block port 8080. However, it is still open. $ sudo ufw deny 8080 Rule added Rule added (v6) $ sudo ufw status numbered Status: ...
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0answers
67 views

can't allow a specific IP in ufw

I've just got myself a VPS and am completely new to running a server. I've installed ufw as I only want to allow access to it from one particular domain hosted on another server. I've read the ...
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0answers
69 views

Can't access Flask from local network

I've already read this thread, but it is not what I'm looking for. I'm running Flask on Ubuntu 13.10 with this configuration, but I can't access it from the local network using the correct ip and port ...
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49 views

Connection timed out on specific ports

We have an apache server running couchdb on port 5985 (not 5984). On my computer, I have Windows 7 and Ubuntu 14 LTS. From Ubuntu, I can connect to the host via http://example.server.domain, but I ...
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6k 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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55 views

Synergy works one way only?

I am running two Ubuntu 12.04 machines connected to the university network. One is a desktop and the other a X230t Lenovo laptop. They are both wired(eth0) to the same network. I am trying to get ...
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2answers
384 views

How do I with ufw deny all outgoing ports excepting the ones I need?

I did the following: ufw default deny outgoing, sudo ufw allow out 80 which I thought would let me use the Internet but didn't can y'all help? Also are there any other ports used by Ubuntu for which ...
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1answer
90 views

Juju security model issues

What plans are there to extend the security model in Juju? We see two significant issues with the current model - no internal firewalling within an environment, and the inability to expose ports to ...
2
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1answer
178 views

ufw firewall disabled - How to turn it back on?

I am using Ubuntu 12.04 and just recently noticed, that my ufw-firewall is turned [off]. I know It's turned [off] by default, but when I set Ubuntu up, I turned [on] the firewall with: sudo ufw, but ...
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1answer
327 views

basic security tools and packages that should be installed on a public facing web server

I'm a newbie in this world and I do not have a lot of knowledge about how security works on Linux systems. I recently created a droplet on DigitalOcean with Ubuntu 13 and I've been setting it up by ...
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1answer
55 views

Ubuntu forward ports, default state, forwarding not working?

im running ubuntu 12.04.4 server. I been googling the nett for answers, but could not find any.. I would like accsess a few web-gui's on my server. I have forwarder the ports in my router, worked when ...
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2answers
736 views

Problem with ufw enable: libkmod: ERROR ../libkmod/libkmod.c

I am trying to enable ufw and this is the output: root@p:~# ufw enable Command may disrupt existing ssh connections. Proceed with operation (y|n)? y ERROR: problem running ufw-init libkmod: ERROR ...
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0answers
90 views

Using Gufw create rule to reject traffic from specific subnet

I am connected to two networks one trusted, one not. Untrusted range is 172.18.0.0/16. (I need some connectivity with it, but not all ports open.) I would like to setup Gufw to reject connections on ...
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1answer
309 views

Iptables and bind9 to forward to google's dns

Hello i have a very hard time on getting along with iptables and bind9 as my internal network dns server. It's configured to forward my queries to google's dns (8.8.8.8). The main problem is i can't ...
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2answers
122 views

Why does DEFAULT INCOMING DENY not stop Firefox from working?

If UFW is actually not an application layer firewall but a "interface to iptables", how can it be if I have by DEFAULT INCOMING DENY and OUTGOING ALLOW setting that ANY internet application is ...
2
votes
1answer
90 views

Need help to make this file work in iptables

I came across the following example of how to use iptables to block internet access when the VPN connection is terminated abruptly: iptables -A INPUT -i lo -j ACCEPT iptables -A OUTPUT -o lo -j ...
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80 views

Setting up a firewall Ubuntu Server 13.10 to specified domain users of a Windows server 2008

So, here's the plan: I want to set up a firewall that allows/blocks certain websites for specified users in a Windows server domain (local); For example: For the user domain.name/user1 I want to ...
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1answer
440 views

Server unexpectedly closed

So I know that similar veins to this topic have been posted, but mine specifically deals with the fact that my SSH login through Putty worked from my desktop and my laptop. However, after carrying ...
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votes
3answers
386 views

apt-get does not work without an internet connection. How can work around this?

I have a host which is firewalled to the point where apt-get is unable to download packages. That host does not have access to a proxy. I know in gentoo I could work around the problem by fetching ...
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1answer
85 views

enable port 9696 on ubuntu server

I am using ubuntu server lts 12.04 on vmware virtual machine. I need to enable port 9696 which is blocked or filtered. When i use the nc -v -w 1 localhost -z 9696 command it shows me the following ...
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3answers
262 views

using nmap for information regarding web host

am trying to get info of host run in linux about open/closed port the host is attacked randomly by hackers changing the content of the page.deleting files,homepage content changed. how can it be ...
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68 views

Port won't open! [duplicate]

I have a server that want to allow connections into it through port 25565, but when I test on http://www.yougetsignal.com/tools/open-ports/ it says they are closed? I have no outfacing interface ...
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82 views

Analyze firewall logs to track intrusion

I have just started this topic where the firewall on my router detects intrusions e.g. Mar 11 14:15:11 kernel warning kernel: [fwlog] Intrusion -> SRC=85.102.133.241 DST=109.78.126.234 ...
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91 views

how to set up iptables for dyndns server?

I have a server running with a dhcp public IP and ddclient updating my hostname from my public IP whenever it changes. My ISP has a feature for dyndns, so my router should automatically map my public ...
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89 views

Iptables help with server on 12.04?

I am trying to create a Minecraft server with port 25565 for me and my friends to access. I used to run one on my mac, where I would change the config for my firewall to allow connections through ...
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265 views

How to log firewall logs to a remote Syslog server

After much reading and unsucessful attempts, I do not manage to send some of my firewall logs to a remote server. Here is my setup: The remote server is a synology NAS, on which the syslog server ...
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1answer
341 views

Why are certain things able to get through ufw firewall?

I should say up-front that I am TOTALLY new to Linux, Ubuntu, and the technical side of networking. I am setting up Ubuntu on a server computer and have learned a bit about configuring the ufw ...
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0answers
246 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, ...