A Firewall is an application or hardware device used to inspect and filter network traffic.

learn more… | top users | synonyms

4
votes
1answer
3k views

DMZ Setup with two firewalls - Traffic from DMZ to LAN and LAN to DMZ

I am setting up a network with machines that need to be accessible from the internet. I'm planning on putting these in a DMZ. Some of the machines in the DMZ need access to machines on the private ...
4
votes
1answer
213 views

Can tcpdump tell accessed port numbers?

I have a server with two NICs, and I would like to only have those ports open on eth1 that are being used. Question How do I get tcpdump to tell me the port numbers that is being accessed on eth1?
4
votes
3answers
307 views

node.js 0.4.0 not serving files to external IPs

When I run the following script http = require('http'); http.createServer(function (req, res) { res.writeHead(200, {'Content-Type': 'text/plain'}); res.end('Hello World\n'); }).listen(80, ...
4
votes
4answers
2k views

iptables, blocking large numbers of IP Addresses

I'm looking to block IP addresses in a relatively automated fashion if they look to be 'screen scraping' content from websites that we host. In the past this was achieved by some ingenious perl ...
4
votes
3answers
3k views

MSMQ Firewall Ports

I'd like to know what ports need to be opened on a firewall in order to allow public read access to an MSMQ private queue. I'm aware that Microsoft publishes a list of ports here: ...
4
votes
3answers
299 views

connected to Centos openvpn but no outside internet access

I am using Windows 7 to connect to a VPS server running CentOS 6.4 First off, I have read every single post and just cant find the solution to my problem I configured my VPN server with openvpn, and ...
4
votes
2answers
159 views

ipv6 multiple addresses and firewall on remote machine

I have an ubuntu server (serverA) which has a couple of IPv6 addresses. One of these is based on it's MAC address, and is known to the network, the other one I presume ubuntu created as a 'private' ...
4
votes
1answer
2k views

ufw blocking apt and dns

I installed ufw on my Debian system like the following: # aptitude install ufw # ufw limit 22 # ufw allow 80 # ufw allow 443 # ufw enable # ufw status verbose Status: active Logging: on (low) ...
4
votes
2answers
2k views

Secure NAT setup with iptables

I have a Debian running device that needs to act as an internet-gateway. On top of that I want to provide a firewall that not only blocks inbound traffic, but also outbound traffic. And I figured ...
4
votes
2answers
454 views

Iptables - Block https response only

I'm quite new to Linux and using iptables. Here is what I am trying to accomplish: I have an ASP.net client that talks with a web service hosted through web-logic on linux. The communication is over ...
4
votes
1answer
434 views

Block outgoing LOIC attacks in a network

I am admin of a small network. Users in our network have access to internet through a squid NAT server. Recently, we have detected that some users are using LOIC to attack servers on the internet. ...
4
votes
5answers
235 views

What are the 'gotcha's' a software developer needs to look out for if tasked with setting up a production ready server?

As a software developer I am very used to installing my typical stack (java, mysql and tomcat/apache) on my development machine. But setting up and securing a production machine is not something I ...
4
votes
3answers
20k views

How can I open a port on my EC2 instance?

I'm working for a client here who has set up an EC2 instance for me to configure. I've installed the software asked for, now all I need to do is open up some ports. I'm currently SSH'd into the ...
4
votes
3answers
182 views

linux Firewall question

I have few generic questions about firewalls and I thought the community up here could help me out. 1) So I recently installed Ubuntu server barebones. I checked for open ports, none were open which ...
4
votes
2answers
774 views

iptables and blocking potentially impossible traffic

I am working on some iptables firewall rules and have seen many examples that suggest the importance of blocking potentially impossible traffic from non-routable IP address spaces. This would include ...
4
votes
1answer
1k views

Best Practice for Setting Up Secure Website [closed]

When Jeff and the StackOverflow team were interviewed on Hanselminutes last fall, Scott was critical of some of the decisions that were made with respect to securing the StackOverflow servers. My ...
4
votes
4answers
343 views

Why on linux machines, any packets do not pass except icmp, but correctly pass on windows

There is a cluster on proxmox. In a cluster have vm - configured router (pfsense). In the our net have Windows and Linux machines. There is the problem: Windows-machines have access to the internet, ...
4
votes
1answer
100 views

Managing security and firewalls in complex, distributed applications

We have a distributed application composed of several different components. For example, we have Python app servers, PostgreSQL DB servers, Redis servers, Memcached, etc. Some of these services are ...
4
votes
1answer
491 views

Firewall ACL management tool

Is there any Firewall ACL management tool which can generate set of ACLs for all my network, including switches, checkpoint, cisco routers, windows, linux etc? I think such tool would make sense as ...
4
votes
1answer
97 views

Seeing strange IPv6 requests being dropped in our firewall

I'm seeing the following IPv6 addresses having requests dropped by our firewall. It doesn't seem to be anything too malicious, but there seems to be a strange pattern to them: ...
4
votes
1answer
152 views

Access, Permissions, and Security for 3rd party developers

Our Marketing department wants to start hiring an outside company to assist in the development and maintenance of our marketing website. The website right now is on FreeBSD (using apache), but with ...
4
votes
1answer
936 views

Cannot loopback to localhost php gateway causing nginx to timeout while setting up firewall with ufw

I'm setting up ufw for the first time. Using Ubuntu 10.04 LTS on an OpenVZ VPN and have the following rules: sudo ufw allow 22/tcp sudo ufw allow 25/tcp sudo ufw allow 53 sudo ufw allow 80 sudo ufw ...
4
votes
3answers
5k views

How to configure remote access to multiple subnets behind a SonicWALL NSA 2400

I have a client that uses a SonicWALL NSA 2400 as their firewall. I need to setup a second LAN subnet for a handful of PC. Management has decided that there should be a second subnet even though ...
4
votes
3answers
2k views

OWA not working from outside the network

I have an Exchange server behind an ISA 2004 server and from inside the network, it's possible to access Outlook Web Access. I have published the server but from outside the network I'm not even ...
4
votes
1answer
89 views

Ban an IP when the server received an amount of data from it

What I need : There are many result for adding a drop rules by an amount of request per laps of time, but I need to drop by received byte count from a particular address over a period of time. ...
4
votes
2answers
109 views

iptables - allow connections to a port only for IP addresses with established state on a different port

I want to allow connections on port x for IP addresses that have a 'established' state on port y. Is this doable by just using iptables?
4
votes
1answer
302 views

pf slows traffic extremely down

I am running a web and mail server on FreeBSD 9.1. The system is installed on a KVM vServer. Everything works fine - until I enable pf(4). My weblog becomes unconscionably slow. So does all the other ...
4
votes
3answers
5k views

pfsense log file retention

We have a pfSense firewall in our datacentre. By default, pfSense is only storing 500K of firewall filter logs, which is only a few hours for us. How can I increase this? pfSense uses clog rather ...
4
votes
3answers
7k views

psexec Couldn't access \\IP/computername The system cannot find the path specified

Tried psexec \\ip.add.re.ss -accepteula -u local_admin -p cmd.exe psexec \\computername -accepteula -u local_admin -p cmd.exe psexec \\computername.fdqn -accepteula -u local_admin -p cmd.exe where ...
4
votes
7answers
24k views

problem with passive FTP behind cisco asa firewall

i've problems connecting to an ftp-server behind a cisco asa firewall using passive mode. ftp works using active and "extended passive" mode, however: when i turn off "extended passive" (epsv in ftp ...
4
votes
5answers
7k views

iptables port forwarding on debian

I'm trying to setup a simple port forwarding firewall and I can't make the basic non-firewall configuration to work. I have setup the iptables script as follows #!/bin/sh # interfaces LAN="eth1" ...
4
votes
1answer
486 views

Why does Terminal Services open WMI, RPC, and NB ports in the firewall?

After adding the Remote Desktop Session Host roll to a server the following firewall rules get created and are enabled by default. Name Group Profile ...
4
votes
1answer
426 views

ipset - recommended method to reload rules after reboot

Am implementing ipset on some Fedora 16 systems. Since ipset rules run in memory and are lost on reboot planning to use a crontab @reboot script to reload the rules and send an email to administrator ...
4
votes
1answer
3k views

Single m0n0wall - Two LAN Subnets - How To Setup

I have two LAN subnets that I need to link together they are 192.168.4.0/24 and 192.168.5.0/24 There is a m0n0wall running on 192.168.4.1. It's LAN connection goes out to our network switch, and it's ...
4
votes
2answers
243 views

Windows XP firewall behavior mysteriously changed

Recently (July 13, 2010) I had a firewall rule that started blocking traffic that had previously been allowed. I have an FTP server running on a non-standard port serving files to the LAN. I had ...
3
votes
9answers
4k views

Why am I Unable to ping port 443 on Ubuntu?

I have opened port 443 through iptables: pkts bytes target prot opt in out source destination 45 2428 ACCEPT all -- lo * 0.0.0.0/0 0.0.0.0/0 6 1009 ACCEPT tcp -- * * 0.0.0.0/0 ...
3
votes
7answers
3k views

Stealthed vs Closed Port

I was reading a website about the difference between stealthed and closed ports. http://www.grc.com/faq-shieldsup.htm A closed port will echo a packet if closed. However, a stealthed port will not ...
3
votes
7answers
2k views

Good linux firewall? [closed]

I am looking for a good firewall for debian 5 which is a web server. Are there any good options apart from iptables? Thanks
3
votes
7answers
4k views

4 NICs or 4-port NIC?

I want to setup a firewall handling two ISP connections and two routers. For that I am planning to use an old Pentium 3 machine. Now, should I use four network interface cards or a 4-port NIC? Do ...
3
votes
9answers
18k views

“account currently disabled” when accessing share, even before logging in

When I try to access a share folder, say \\share-folder, I get the following error message: logon failure: account currently disabled This seems strange to me, since there is no 'account' to be ...
3
votes
8answers
41k views

How to enable sshd on Fedora 11?

I have just installed Fedora 11 on my desktop system and would like to have sshd work. These are the steps I have done: Enabled sshd as a trusted service using system-config-firewall Restarted sshd ...
3
votes
5answers
215 views

Good firewall for Vista? [closed]

I just bought my first laptop. It runs Vista, and I need a software firewall to protect both its Ethernet and wifi connections. I use the free Comodo Personal Firewall on my desktop, but I read that ...
3
votes
3answers
1k views

What are the security risks of using pfsense in a virtualised environment?

I am thinking of using pfsense on my ubuntu server box. I'd virtualise pfsense with virtualbox, and have it route and firewall all traffic both on and destined to my server as well as the the rest of ...
3
votes
6answers
1k views

Are there any security benefits to having a dedicated firewall?

Are there any security benefits to having a dedicated firewall rather than having a firewall established on a router? Thanks.
3
votes
3answers
328 views

Open Ports: Apache vs. IIS

I just had an interesting meeting with security guys and the main point of this meeting I wanted to have some backup on is: Apache is secure, because it only needs port 80 and 443 (for http and https ...
3
votes
4answers
162 views

Is there a general guideline to setting up Firewall policies for Small Business?

I understand that each Business has it's own needs and situation, but I'm looking for a general guideline to commonly blocked services and ports and other policies to be looking for when configuring ...
3
votes
4answers
1k views

What are the risk if all Outgoing connection/ports are open?

To solve facebook authorization connection on our server, we've decided to open all outgoing connection/ports in firewall to see if it's really security issue. after allowing, the facebook connection ...
3
votes
5answers
2k views

When would I open Port 53 for DNS?

Locking down an application server. The server hosts a web app that is served via http. There are a few other ports open as well. Port 53 is open for DNS. Why would I need this? Extra: (Do not ...
3
votes
3answers
305 views

What's the situation that requires stateful firewall?

I just know there is two kind of firewalls. Stateless and stateful. It's hard to determine what kind of firewall I have to use. Currently I have to run firewall within same machine runs services, ...
3
votes
3answers
4k views

How long does it take for an iptables rule to apply?

How long does it take for an iptables rule to apply? I use a script with the code below in an attempt to block hosts, but they don't appear to take immediately. Is there some delay, is iptables not ...