I am told (but am prepared to be smashed to the ground) that the Router (with it's hardware firewall) should be OK with the XP firewall running as well ..... not too sure about Zone Alarm, but you will soon get to know as the signal (to wireless PC's/Laptops)will keep dropping / disconnecting etc, in which case disable ZA, if not leave it running. ;-)
Currently I use Zone Alarm software on my computer. If the computer is now connected to a router (wireless), is it necessary to still have this software on the computer. If not, what is the consequences of leaving it on?
It can be argued that since you are using your router's firewall (NAT and/or SPI), you don't really need your software firewall. Still, I prefer both. Normally, your hardware firewall will prevent access to your LAN from the WAN (internet) unless you provide access. I use my software firewall to monitor programs and apps trying to gain access to the WAN. Depending on how you use them, software firewalls can aid in the detection of spyware. In summary: Hardware firewalls - protection from intruders. Software Firewalls
- monitors data trying to gain access to the internet without your knowledge or approval.
The only thing the PFW solution can do is stop outbound that the typical NAT router cannot do or protect other machines on the LAN, which really doesn't do much good if the machines are doing resources sharing with each other. Typical NAT routers running SPI and some other FW like features are not FW appliances running ture FW software.
A PFW solution is not a FW. It doesn't separate two networks. The PFW solution is only software that provides machine level protection. Anything running at the machine level, you should not treat it like a crutch and think that it's a stop all and ends all solution and trust it completely. as malware and Trojans can circumvent and defeat it.
If the NAT router has logging capabilities, then you should enable its logging and use a logviewer like Wallwatcher, Kiwi Syslog Daemon or others and watch inbound and outbound traffic to/from the router to possible dubious remote IP(s).
I would say implement the PFW or some other packet filtering software on the machines to supplement a NAT router.
If you had a FW appliance, then I would say you could dump the PFW solution on the machines.
If you have a NATed router, your hosts are pretty well protected from outside. But viruses and malware coming in on carelessly handled email may infect a computer with a zombie, and a firewall can do something which the router can not - limit damage from programs running inside on network.
A NAT and/or SPI router can usually co-exist with a software firewall without any problems. On the other hand, the Windows firewall often has a fit when used in conjunction with a third party firewall.