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

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Host DHCP services on server or firewall/router?

I've been debating with myself about the best place for hosting a LAN's DHCP services. I have the option of either on a sonicwall firewall or a Windows 2008 server. The two things I was looking for ...
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1answer
55k views

TCP/IP ports necessary for CIFS/SMB operation

If I want to allow Windows networked drives between two firewalled computers, do I need to open ports 137-139, or is port 445 sufficient? I have to submit a form and get approval to open firewall ...
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3answers
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Placing a server in the DMZ vs opening firewall ports

When should you place a server in a DMZ vs opening ports on the firewall and keeping it within the network? I'm referring to active directory servers, IIS servers, and mostly things on a windows based ...
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6answers
905 views

Skype in a business - what's your view?

We currently don't allow Skype usage on the LAN. The reasons ultimately come down to that great cover-all of "security", though I have to admit that these days I'm not sure if Skype has turned into a ...
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3answers
333 views

Can't access Exchange OWA from Wireless Subnet - Firewall rule?

The Problem The issue is that I can't access port 80 (or 443) on the Exchange server, unless I add a blanket rule to allow all traffic from the client to the server's subnet. If I add a rule to ...
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3answers
915 views

ESXi hosted on public IP without firewall

So I've got an interesting problem. I currently rent a couple of servers from Hetzner (a German hosting provider). Each server has a soft firewall and does something like web hosting / database. I ...
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3answers
3k views

Blocking a country (mass iP Ranges), best practice for the actual block

This question has obviously been asked many times in many different forms, but I can't find an actual answer to the specific plan I've got. We run a popular European Commercial deals site, and are ...
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5answers
401 views

recommend firewall options for a dedicated server

I'm looking for recommendations on firewalls for a dedicated server that will be hosting a few websites of average traffic (5000 uniques monthly). the hosting company has port and full hardware ...
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5answers
809 views

Is it beneficial to chain multiple firewalls at the perimeter?

I'm currently running ISA 2004 and will soon be running an Untangle box. I've always felt a tiny bit safer putting these more advanced software firewalls behind a dumb hardware firewall (like ...
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3answers
968 views

Can our firewall detect traffic sniffing inside the network?

We use Cisco ASA's firewall and NAT functions in our network (200 computers). Is there any possibility to configure Cisco ASA to detect traffic sniffering (for example wireshark) and network ...
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3answers
7k views

Denying ICMP type 3 code 4 traffic - good or bad?

Investigating a slow VPN connection (Cisco ASA IPSec) to a remote office, I noticed on our firewall a lot of access rule matches: Denied ICMP type=3, code=4 from *ip_address* on interface outside I ...
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1answer
757 views

tcpdump output with iptables REJECT policy enabled

Quick question. I have a firewall with these simple rules: iptables -A INPUT -p tcp -s 127.0.0.1/32 --dport 6000 -j ACCEPT iptables -A INPUT -p tcp -s 192.168.16.20/32 --dport 6000 -j ACCEPT ...
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1answer
5k 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 ...
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2answers
6k views

Should I rate-limit packets with iptables?

I'm using iptables on Ubuntu Server. It's a web server on a VPS. I'd like to know if I should rate-limit packets. If so, what should I rate-limit? And should I do so globally or per IP address? ...
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1answer
227 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?
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3answers
323 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, ...
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3answers
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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: ...
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1answer
893 views

Linux NFLOG - documentation, configuration from C

Several different places (e.g. http://wiki.wireshark.org/CaptureSetup/NFLOG) recommend using Linux's "NFLOG" firewall module to capture packets generated by a particular UID, like this: # iptables -A ...
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3answers
1k 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 ...
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2answers
187 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' ...
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5answers
11k views

Why is this iptables file line failing in CentOS 6

Hi could could anyone help me understand why line 15 is failing supposedly in my iptables file. I'm using CentOS 6. When I try to restart iptables service, get the following: [root@dbserver ~]# ...
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2answers
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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 ...
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2answers
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How can I track down what part of pfsense is blocking website access?

I've got a PFSense firewall/gateway on our network. Everything works great except for the fact that I cannot access one specific website. Pfsense is running the following packages Country Block ...
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2answers
587 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 ...
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1answer
491 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. ...
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5answers
239 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 ...
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3answers
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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 ...
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3answers
188 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 ...
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2answers
997 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 ...
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2answers
934 views

Windows Firewall - blocking IP address ranges en masse - performance considerations?

One of our services is an extranet for the exclusive use of our 200 employees across the UK. We're seeing a huge number of login attempts from China, Russia, Ukraine and Nigeria. I have large lists of ...
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4answers
683 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, ...
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1answer
107 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 ...
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1answer
823 views

Firewall ACL management tool [closed]

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 ...
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1answer
102 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: ...
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1answer
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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 ...
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3answers
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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 ...
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3answers
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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 ...
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1answer
100 views

firewall and private cloud

We have a private bay in which we built a private cloud with vmware vSphere. We received directly the web trafic on a firewall VM and then we forward the trafic to the appropriate VMs. We are worry ...
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1answer
127 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. ...
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2answers
126 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?
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1answer
573 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 ...
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3answers
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automatically block IP address after many failed login attempts

I am receiving a lot of failed login attempts (1 per sec) on a Windows 2008 server, I have already set local security policy to automatically lock an account after too many login attempts, but is ...
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3answers
6k 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 ...
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3answers
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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 ...
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7answers
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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 ...
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1answer
590 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 ...
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1answer
605 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 ...
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1answer
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How do I route between interfaces in PFsense?

I have a PFsense router which divides a single WAN connection into three NAT networks on three interfaces: LAN, OPT1 and OPT2. This allows me to segregate my network so that computers on the OPT1 and ...
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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 ...
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Correctly setting up UFW on Ubuntu Server 10 LTS which has Nginx, FastCGI and MySQL?

I'm wanting to get my firewall on my new webserver to be as secure as it needs to be. After I did research for iptables, I came across UFW (Uncomplicated FireWall). This looks like a better way for me ...