Concerned with software or hardware firewalls

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9
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3answers
12k views

Proxy vs. Firewall

I understand that very simply put a proxy is a sort of 'man in the middle' allowing/denying access to certain services/resources. Strictly in terms of security (I mean here privacy, parental control ...
21
votes
6answers
5k views

What is the difference between $200 and $1,000+ Firewalls?

Instead of asking about the pros and cons of specific hardware, I thought I would ask a broader question: What are the differences between really expensive and inexpensive firewalls? What extra ...
7
votes
3answers
662 views

Firewall says that a program that I'm developing is trying to connect to the Internet

I'm seriously confused about this, since the program is entirely developed by myself and has no means/functionality to connect to any network/the internet whatsoever. I'm a software engineer but not ...
2
votes
4answers
2k views

Best way to push data to a client without being blocked by firewall

I'm asking this question here since I think people on this forum probably have the best knowledge of firewalls and routers. Say I'm designing a multi-player game and I want to push data to the client ...
3
votes
1answer
5k views

Is opening both TCP/UDP less secured than just TCP or UDP when needed and why?

If application needs opened port X UDP, or X TCP combination. Is there any potential risk by opening both UDP/TCP as I usually am not sure which one the application uses?
3
votes
1answer
899 views

Mac sending hundreds of packets to gateway

I've got a user on my work network who brings her personal laptop (macbook) in for work. They've been having some horrendously slow network issues on everything past that hub, so I did some packet ...
10
votes
4answers
11k views

How to listen to all ports (UDP and TCP) or make them all appear open (linux)

I got an external Debian server. The problem is that my university campus doesn't allow connections to go outside when the port is different than TCP port 22, 80, 443, or UDP port 123. I tested them ...
15
votes
5answers
20k views

What is the best practice for placing database servers in secure network topologies

I have a classic DMZ architecture: My webserver is placed in the DMZ. The webserver needs to communicate with a database server. This database server is the most critical component of my network ...
4
votes
2answers
591 views

What is the background of the Reference Counter Overflow in Microsoft TCP/IP (MS11-083)?

How unique is this bug? Is there a more sophisticated and well-studied attempt behind? Is it accidence? The article below says "continouos stream to UDP". What stream? Just an hour stream of zeros? ...
4
votes
1answer
805 views

IP address filtering vs web application security

We have a web application behind a firewall that requires no user authentication. If we open up access to this application via the firewall to a small list of IP addresses what is the risk of ...
14
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6answers
14k views

How important is NAT as a security layer?

I've signed on to help a department move buildings and upgrade their dated infrastructure. This department has about 40 employees, 25 desktops, an old Novell server, and a handful of laboratory ...
4
votes
2answers
623 views

Firewall design for big enterprise business

I am wondering if there is any best practice firewalling rules that should be put in effect in most modern networks. For example should the network atleast have the following firewall zones? Client ...
5
votes
1answer
1k views

I'm having a DDoS attack, my hosting company is stupid, and I need to know what is hapening

So ok, right now my windows 2003 dedicated server is under attack by some guy who's flooding UDP packets (~90.000 packets/sec) on my 100Mbps server for the last 8 hours. I'm on a shared port, so I'm ...
6
votes
2answers
1k views

How do experienced users test stateful firewall?

How do experienced users test stateful firewall with TCP/IPv6? My test case includes: echo reply without request tcp ack without syn Are there any more test cases, especially with IPv6?
8
votes
4answers
3k views

Is Windows Firewall suitable for running in a production environment?

Is Windows Firewall suitable for running as the sole protection on a production web server? Is it hardened enough? Robust enough? and tested enough? I'm running a VPS with Rackspace on their cloud ...
1
vote
0answers
397 views

PF NFS Firewall Issue [closed]

I have a question about NFS and PF (freebsd). I know that NFS uses both TCP and UDP to connect to the client along with a bunch of daemons that use random port numbers. Both the NFS server and ...
6
votes
2answers
3k views

I'm getting lots of unfamiliar connection attempts, what do I do?

I'm running Mac OS X and I have the system firewall enabled and I have stealth mode enabled. I opened up my system console and noticed that I'm getting tons of blocked connection attempts from places ...
7
votes
1answer
5k views

How is tunnelling SSH through Poxytunnel/HTTPS different from doing it through SSL with Stunnel?

In an answer to What is the difference between SSL, TLS, and HTTPS, it's said that HTTPS is HTTP over SSL/TLS. That is, an SSL/TLS connection is established first, and then normal HTTP data is ...
8
votes
5answers
7k views

What kind of attacks against home router's NAT do exist?

I always thought NAT was some kind of a security feature and I still think it is, because if it didn't existed the internet, respectively the clients behind NATs, would be even more insecure, since ...
3
votes
4answers
428 views

What does a switched network protect us from? What does it not protect us from?

There seems to be some misconceptions regarding what a switched network will protect us from, and what technologies/precautions a secure environment requires when segmenting trusted users from hostile ...
4
votes
3answers
704 views

Servers: Why a separate device for a firewall, aside from reduction in IP spoofing or increase in performance

Why should the firewall be outside the server, excepting these two items Take the performance impact of noise off of the server. Add a physical layer between devices so they can be on separate ...
5
votes
5answers
2k views

What are the likely threats to a public-facing DB instance?

Quick intro: Small company, VERY limited resources. I pretty much do everything including take out the trash. We've been running an instance of MySQL internally for years and it's worked OK, but I ...
3
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2answers
2k views

Reverse shell connections

Why are reverse shell connections so popular in the event of a successful intrusion? Many "hacking" videos show this and it is often seen in practice. Would not most servers restrict outgoing ...
1
vote
3answers
3k views

Power friendly home router, firewall, IDS/IPS setup? [closed]

For those that like to manage their own firewall and run IDS/IPS on their home networks, I'm curious - what are you using and is it power friendly? I used to have a shelf full systems doing various ...
10
votes
7answers
5k views

What security implications are there for allowing outbound SSH traffic?

My school currently blocks outbound SSH traffic. Users inside the network cannot use Port 22, and attempting to make an SSH connection over another port is also blocked. (I'm assuming the firewall ...
2
votes
5answers
658 views

How do a firewall's rules for individual programs work?

I kind of know that how a firewall's rules for IP/port work, but I have no idea how a firewall deals with individual programs. In other words, how does the firewall know a program wants to access the ...
2
votes
3answers
2k views

Use a Common Firewall for two Different Subnets

I want to implement a security scheme in a new network configuration. There are two buildings for the client: Office Building 1 (OB1) with address 10.0.0.0 / 255.255.255.0, Gateway 10.0.0.1 ( ...
5
votes
2answers
19k views

What advantages and disadvantages do Palo Alto firewalls have, compared to others in the market

I am about to start an evaluation process for firewalls. I have experience with Checkpoint and Juniper, but I don't have any information on Palo Alto networks, other than their marketing stuff. So I ...
1
vote
4answers
7k views

Ignoring broadcasts to 10.0.0.255 using iptables

I'm trying to drop logging packets that are destined for 10.0.0.255 by using the following rules: $IPTABLES -A OUTPUT -d 10.0.0.255 -j DROP $IPTABLES -A FORWARD -d 10.0.0.255 -j DROP It ...
6
votes
2answers
14k views

What is best practice for separation of trusted zones from a DMZ with a single firewall?

At our organization we have a single firewall sitting between our internal zones and the public internet. Currently all of our trusted zones are defined as different vlans on a layer 3 switch plugged ...
4
votes
1answer
351 views

Placing a firewall—without creating a new subnetwork

I have a couple of networks that have multiple IP addresses, and where I have absolutely no choice as to the equipment used for the network's edge router (the device that connects both to the LAN and ...
3
votes
2answers
308 views

Can ipopts be used to circumvent a pf or iptables firewall source IP based blocking?

Can one use ipopts, and in particular IP source routing, to circumvent source-based blocking in pf or iptables? For example, with OpenBSD's pf: block in all # default deny block out all pass in on ...
12
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4answers
29k views

Tips for a secure iptables config to defend from attacks. (client side!)

Own examples: ############### # KERNEL PARAMETER CONFIGURATION # PREVENT YOU SYSTEM FROM ANSWERING ICMP ECHO REQUESTS echo 1 > /proc/sys/net/ipv4/icmp_echo_ignore_all # DROP ICMP ECHO-REQUEST ...
5
votes
2answers
3k views

incoming packets in server

I have enabled iptables logging for packets coming from the outside -A INPUT ! -s 192.168.218.0/24 -j LOG Now i am seeing lots of incoming packets from unknown addresses Jun 5 14:54:56 localhost ...
7
votes
6answers
320 views

Why shouldn't I run other applications on a Firewall?

If I want to use Ubuntu 11.04 as a Firewall in SOHO environment, then I just can't figure out what is the bad thing about installing GUI on it (e.g.: XFCE)? The only opened port to the world (wan ...
1
vote
2answers
582 views

Is the level of traffic normal against my blocked ports?

I was recommended by my brother to direct the question here about the level of traffic I get against several of my blocked ports. I run pfsense 1.2.3, router in bridge. Behind pfsense I have: 1x ...
2
votes
2answers
4k views

IPTables default security rules for a gateway/router?

On a router such as dd-wrt or tomato, what would be some default iptables rules? I am asking for rules on a router/gateway - For example; blocking SYN flood attacks, or XMAS attacks. The basic ...
5
votes
2answers
3k views

Firewall Configuration Audits

I'm looking to perform policy audits against firewall configurations and/or rulesets. This should be performed independently of any configuration management systems, ideally by operating off the ...
5
votes
2answers
875 views

What are the risks associated with relying on IPSec IP Filtering?

When using Windows IPSec for IP filtering whenever a filter is added you need to have a "mirror" rule (by checking the "Mirrored. Match packets..." tickbox). Because IPSec Filtering is not stateful, ...
6
votes
2answers
4k views

Getting self-signed SSL certificates for all https connections made from some premises

Context: I'm currently working as an expat for my company in a country where the Internet is notably untrustworthy. It made the headlines a few months ago for stealing facebook, twitter and gmail ...
5
votes
4answers
2k views

what is a good public available iptables script for ddos mitigation?

what is a good public available iptables script for ddos mitigation?
6
votes
5answers
1k views

Firewall demo - iptables

I have to make a demonstration about firewalls in my class as a student(university). It should be implemented using iptables on Linux. I am reading all the theories around them but I can't figure out ...
18
votes
2answers
6k views

Reject IP packets with an ICMP error, or just drop them?

Consider an internet-facing host (the outer firewall). What should be done with undesired traffic: just drop it, or send back an ICMP error such as port unreachable? (In Linux terms: iptables -P DROP ...
19
votes
5answers
10k views

Do you detect/react to DNS tunnelling?

I've just seen a talk about tunnelling TCP/IP over DNS requests, because port 53 UDP is usually open and unfiltered. What techniques exist to detect and block such tunnels, and have you ever seen that ...
6
votes
4answers
532 views

What kind of IT security applications do you guys run on your laptop/desktop? [closed]

I know a lot of people run different security applications on their laptops/desktops. I use Little Snitch on my Macbook Pro. I like to know where my applications are sending data and where I am ...
6
votes
3answers
466 views

When you make a revision of rules on a firewall, how do you add credibility/customer satisfaction to your final consideration?

When, for a vulnerability assessment, you need to report the security consideration about a firewall's configuration rule-set, after the audit on the rule-set you make a report about security concerns ...
4
votes
3answers
4k views

How do I configure nmap to verify my firewall is performing stateful packet inspection?

As part of a compliance audit, I need to run a routine scan that verifies that our firewalls are performing stateful packet inspection on incoming packets. I have a dedicated server outside our ...
4
votes
1answer
1k views

Firewall rules to block unwanted protocols on given ports

Does somebody has an idea, that what kind of iptables/pf rule must i use to achieve this?: i only want to allow these connections [on the output chain]: on port 53 output only allow udp - dns on ...
10
votes
4answers
1k views

Software vs Hardware Firewalls

I read an article (can't find link) recently that advocated dumping software firewalls if you had a hardware firewall. I was just curious as to the take on Firewalls in general for a small-medium ...
2
votes
2answers
454 views

What compliance framework is appropriate for firewalls

As a more corpose vulnerability assessment and penetration test, one step of our activity is to review from a security perspective the policy of some firewall. In our society we have a deep ...