What firewall can and cannot block

Depends on the firewall...

Juergen Nieveler

They can't block highly unconstrained, largely unanswerable questions from reaching comp.security.firewalls, for one.

This is a serious answer, because I'm going under the assumption that you are probably a business owner or manager whose pinkies happen to have been broken in a freak typing accident.

You can have a firewall can block everything... but then nothing will get though. At that point you might as well not have a network connection.

You want things to get through though, well, certain things. So you try to choose what to let through. The problem is that it takes a great deal more information to separate what you want from what you don't want than can be conveniently communicated in a newsgroup thread. You have people reading this list who are usually quite generous with the bandwidth that comes out their fingertips, but this question is broad enough to be an abuse of that generosity.

What you need to do is either pay someone for their education and experience in this area or acquire relevant education and experience of your own, which you may legitimately be trying to do. The open-ended nature of your inquiry, however, suggests that you have no basis for estimating what the education will cost... let alone the experience. In either event, the place to start is your local library. Go to the far left hand side of non-fiction where the Dewey decimal numbers begin with zero. Look for books on security and firewalls among those on Dreamweaver and Excel. They'll usually be about three inches thick. You'll need to read at least 3 books of that nature before your bullshit detector can be calibrated to learn anything. At that point, you might be ready to ask a question or make an intelligent hiring decision on a security consultant.

Chris

A FW can block all access inbound and outbound. There are two(2) types of FW in general; Hardware and Software FW. If you have a cable or dsl connection with a modern modem, you probably all ready have a HW FW that utilizes Network Address Translation adequately without a router. You will have to research that yourself by manufacture or consult your ISP help online. The Software FW blocks all ports(software) from inbound attacks and unsolicited port scans. The windows xp/vista FW will only block inbound. Many Software FW like ZoneAlarm (the easiest free FW available to learn with) also blocks outbound with permissions that you can assign, but in the case of ZA, a server will also assign permissions at initial start up of an application that wants access to the Internet. There are many free FW for trial out there and a good website would be

a firewall primarily blocks any unauthorised traffic comming from untrusted network to trusted network.a firewall cant stop/clean a virus comming into your network its just a connection manager.

below are some types of firewalls..

packet filter -- rules can be created to block traffic based on IP/ Port Number

stateful firewall -- firewall decides whether to allow a traffic or not by refering to a state table(consisting of details whether a session initiated or not)

application proxy -- primarily used to block applications(e.g yahoo messenger) whose port numbers keep changing dynamically.

most of the todays firewalls have the above capabilities.

hope that clarifies ur doubts...

unsolicited

snipped-for-privacy@gmail.com wrote in news:c5716e7e-cb5d-4fb1-8ce6- snipped-for-privacy@m34g2000hsb.googlegroups.com:

Good question!

Firewalls can be set to block nothing, everything, and anything in between those two extremes.

Good luck with your configuration.

CJ