Bob Jensen's Threads on
Firewalls and Virus Protection
Bob
Jensen at Trinity University
Note that firewalls are not generally
intended to protect against viruses. The protect against invasion of the
computer by hackers intent on doing bad things such as creating entry trap doors
to your systems. For more information on firewalls, go to http://www.w3.org/Security/Faq/wwwsf3.html#SVR-Q6
Tom Hicks brought me up to date on wireless home firewall
computers. He recommends Linksys products such as the one at http://www.linksys.com/splash/wcg200_splash.asp
The Linksys Wireless-G Cable
Gateway is the all-in-one solution for Internet connectivity in your home. The
Cable Modem function gives you a blazing fast connection to the Internet, far
faster than a dial-up, and without tying up your phone line.
Connect your computer to the
Wireless-G Cable Gateway via USB, or take advantage of the built-in 4-port
10/100 Ethernet Switch to jump start your home network. You can share files,
printers, hard drive space and other resources, or play head-to-head PC games.
Connect four PCs directly, or daisy-chain out to more hubs and switches to
create as big a network as you need. The built-in Wireless-G Access Point
allows up to 32 wireless devices to connect to your network at a blazing
54Mbps, without running cables through the house. It's also compatible with
Wireless-B devices, at 11Mbps. The Gateway's Router function ties it all
together and lets your whole network share that high-speed Internet
connection.
To protect your data and privacy,
the Wireless-G Cable Gateway features an advanced firewall to keep Internet
intruders and attackers out. Wireless transmissions can be protected by
powerful data encryption. Safeguard your family with Parental Control features
like Internet Access Time Limits and Key Word Blocking. Configuration is a
snap with any web browser. With the Linksys Wireless-G Cable Gateway at the
heart of your home network, you're connected to the future.
Zone Alarm --- http://www.zone-alarm-pro.com/
In reply to a message about installing a firewall on a
home computer, Chula King wrote the following in reply to a firewall question
posed by Amy Dunbar:
I too use Zone Alarm,
and have been quite pleased with it. I've also tried Black Ice Defender and
don't think that it does nearly as good a job as Zone Alarm.
While not anti virus
software, Zone Alarm will quarantine "suspicious" e-mail
attachments. In addition, it blocks both incoming scans to one's computer and
outgoing messages produced by spyware.
Chula King
The University of West Florida
Reply from Amelia Baldwin
Amy,
as for hacking and
such, another vote for zonealarm on your cable internet enabled computer. it
is not difficult to use. yes, your cable company probes your IP a few times a
day but that's NOTHING compared to the number of times you will get pinged or
probed or God know what else by seemingly random attempts from total
strangers. :o( Zonealarm blocks and tracks these things and if you weren't
frightened before you put up a firewall, you will be when you seen how many
accesses were going on or at least attempted!
as for anti-virus,
keep an anti-virus program running and keep it's virus signatures up to date
(the number of folks who have the software but never update it just astounds
me) and never ever open an email attachment that you are not expecting even if
it IS from someone you know. some viruses send seemingly random attachments
via the email software of the infected computer to folks on the address list,
thus you might actually receive what looks like a legitimate attachment from a
known user and it will have a virus.
just my $0.02
Amelia
Reply from Bill Spinks
If you have a high
speed continuous connection, you need a fire wall! (ZoneAlarm is free and
pretty good). I monitor my log of blocked hits and probably get 10 or 15 a day
during the week and 20 to 30 on a weekend days. Interestingly enough when I
have checked the reverse address of those URLs that are trying to connect with
my computer, a large number of them are from China, Korea, and Taiwan -- some
have even come from middleschool computers (or so it is reported on http://samspade.org
.)
If like stamp
collectors you like to travel the world in symbolic form, you can report your
"intrusion" back to the tech supervisor of those sites. Sometimes
you hear, most times you don't, but it makes for some interesting
correspondence from interesting places.
billspinks
You can read some Zone Alarm reviews
at
http://www.epinions.com/cmsw-Utilities-All-Zone_Alarm/display_~reviews
Reply from Brian Zwicker
In the Untouchables,
Sean Connery said something like: "... never bring a knife to a
gunfight" (I have removed the ethnic/racial slur)
Faced with the same
incredibly high number of approaches to my home computer setup, I decided to
bypass emulating a firewall, and go for the real thing - a firewall.
It turns out not to
be very expensive, because I used an older pentium 2 computer I nad in the
basement, a couple of ethernet cards, and some software from gnatbox. The
computer, by the way boots and runs from a floppy disk! You do not even need a
dedicated monitor, except for setting up. The whole system now runs from my
desktop computer and you can reset various parameters from there.
Some caveats are that
to do e-mail, I had to obtain the real address of my cable provider's mail
server, because the gnatbox software could not be made to work without this.
It also took a couple of weekends to get everything wotking. I also don't know
how, or even if, this would work with many educational computer networks.
On the plus side,
since the firewall computer talks to the outside world, and I talk to the
firewall, it seems it would take a verrrry determined hacker to get past this
setup, and although I did have a number of virus problems prior to the
firewall going in, I have had nothing since.
One other thing is
the list that gnatbox will show on demand of attempted accesses to the
firewall. It dumps the older attempts after 12 hours, but the available list
is always many screens long. I would say that if even 99.99% of all attempts
are benign, at least 4 or 5 each week would be a real attempt to get through
in order to damage something. Pretty scary.
Cheers,
Brian Zwicker
"Product Round-up:
Firewalls," Syllabus, February 22, 2002, pp. 40-41 ---
http://www.syllabus.com/syllabusmagazine/article.asp?id=6091
Whether a campus computer network is
large or small, it needs security that blocks unauthorized access and
intrusion. On large networks, the increasing diversification of network
activity—including wireless access, telecommuters, and virtual private
network (VPN) connections—complicates the issue. In order to ensure
security, therefore, it's best to implement various solutions, including
antivirus protection, intrusion detection software, and firewalls.
Firewalls are the front line of
defense, the border guards against unauthorized movements of users into or out
of the network. Firewalls don't analyze messages but instead simply prohibit
access to anything that doesn't meet specified criteria. There are many kinds
of firewall products: personal firewalls, which reside on one specific
computer, as well as enterprise-level network firewalls. Software firewalls
are less expensive and more available than hardware solutions. However,
hardware firewalls are always on and don't interfere with other software
running on the computer. We've surveyed several of the top enterprise firewall
products in this issue, from Microsoft Corp. Windows NT products to Linux and
Apple Computer Inc. Macintosh devices.
For Windows
NT
CiscoPIX
The Cisco Systems Inc. Secure PIX 500
series is one of the leading Windows NT firewall products on the market. The
series encompasses five models scaled for a variety of customer needs and
network sizes, from the enterprise market all the way down to the small office
environment. At the enterprise level, the PIX 535 provides a throughput of 1
gigabit/sec with the ability to handle up to 500,000 connections concurrently.
Administrators of a smaller network may prefer the PIX 525, which delivers 370
megabits/sec and 280,000 simultaneous sessions. Each model has built-in IPSec
encryption, allowing both site-to-site and remote access VPN deployments for
off-campus users. Each model features an easy-to-install, integrated
hardware/software appliance that uses a non-UNIX, secure, real-time, embedded
system. The PIX firewalls may be managed by the PIX Configuration Manager or
centrally managed by the Cisco Secure Policy Manager, which can manage up to
500 PIX firewalls, integrated software deployments, and site-to-site VPN
installations. Contact: Cisco Systems, Santa Clara, Calif., (800) 553-NETS, www.cisco.com.
CyberwallPLUS
Designed to protect Windows NT/2000
systems and enterprise computer networks, the Cyberwall system consists of a
central management system (called CyberWallPLUS-CM) and a family of four
firewalls that secure desktops, servers, Internet access, and enterprise
networks. Cyberwall's approach layers a packet filter firewall and packet
inspection with an active intrusion protection system. This combination gives
the administrator fine-grain access control at the host level. CyberwallPLUS
features pre-configured security templates that help administrators install
the product quickly, regardless of their security experience level. The
workstation version of the product also includes the ability to limit or
forbid access to particular applications, such as Napster or Doom. Contact:
Network-1 Security Solutions, Waltham, Mass., (800) NETWRK1, www.network-1.com.
Jetico Personal Firewall 1.0.1.6
http://www.jetico.com/
Unwarranted attacks from unscrupulous hackers are
increasingly common, and users concerned with such activities would do well
to take a look at the Jetico Personal Firewall. With this application, users
will have three levels of protection. The application will effectively
filter network packets, application-level network events, and of course,
various Trojans that might try to sneak into Internet Explorer or some such
browsing application. Jetico Personal Firewall 1.0.1.6 is compatible with
Windows 98 or newer.
Symantec Enterprise Firewall 6.5
Symantec Corp. Enterprise Firewall
(formerly known as the Raptor firewall) features a unique hybrid architecture
designed to provide transparent firewall protection without slowing approved
traffic. Its support for a broad selection of user authentication methods such
as RADIUS, digital certificates, Lightweight Directory Access Protocol, and NT
domain authentication gives administrators the flexibility to use existing
security databases in the users' environment. Symantec's product is, above
all, flexible. Users can choose between a hardware- or software-based solution
for high availability and load balancing as well as integrated Web and Usenet
content filtering. Developed for the Windows NT/2000 and Sun Microsystems Inc.
Solaris platforms, Symantec touts an intuitive interface and range of
easy-to-use tools for configuring, managing, and maintaining the firewall.
From a central console, administrators can manage security policies for both
local and remote firewalls and obtain a variety of security logs and
management reports. An optional Symantec Enterprise VPN (formerly called the
PowerVPN) can be combined with a personal firewall product and the Symantec
Enterprise Firewall to extend the corporate perimeter to provide secure,
low-cost connectivity for remote offices and telecommuters. Contact: Symantec,
Cupertino, Calif., (408) 517-8000, www.symantec.com.
SonicWALL GX 2500 and 6500
The SonicWALL GX 2500 and 6500
Internet security appliances deliver an integrated security solution,
combining a high-bandwidth firewall and VPN hardware for large enterprise
institutions. With application-specific integrated circuit security
architecture, ICSA-certified packet inspection technology, and the inclusion
of 100 VPN clients for secure connectivity of dial-up users connecting from
off campus, the GX products compete with other firewall packages in this
class. Administrators can manage the GX 2500 or 6500 using a variety of local
and remote options, including CLI, a Web management interface, and Simple
Network Management Protocol. Also included is SonicWALL ViewPoint, a
Web-based, graphical reporting tool for managing and monitoring network
security. For mission-critical security, users can install two SonicWALL GXs,
as primary and secondary appliances, creating a redundant pair. There is even
a built-in redundant power supply. The scalable design accommodates future
upgrades and interface types. The product supports seamless integration of
other SonicWALL security appliances, such as Network Anti-Virus and Internet
Content Filtering, to provide all-in-one security. Contact: SonicWALL,
Sunnyvale, Calif., (888) 222-6563, www.sonicwall.com.
For Mac OS X
DoorStop Server Edition
Open Door Networks sells two products
that work in combination to provide security for Macintosh-based servers. The
first, a firewall called DoorStop Server Edition, includes advanced,
server-specific security features and is specifically intended to run with
such servers as AppleShare IP, WebSTAR, and ShareWay IP Professional. The
second, Who's There Firewall Advisor, works with DoorStop to analyze each
attack. Who's There provides administrators with critical information,
including access attempts by service type and accessor IP address, built-in
information about the most common attacks and their applicability to the
specific Mac OS environment under which Who's There is running, and an
automated "Whois" lookup to determine details of the accessor's
network. The system can also automatically draft an e-mail that can be used to
notify the administrator of the access attempt and provide him or her with
details that may be useful in tracking the attempt. Who's There works with
DoorStop as well as Symantec and IPNetSecurity products for the Macintosh.
Contact: Open Door Networks, Ashland, Ore., (541) 488-4127, www.opendoor.com.
On January 7, 2000 the Digital Duo (PBS)
show featured do-it-yourself firewalls. On campus, most of us hide behind
the University's firewall. For our home computers, however, there are a
range of confusing firewall alternatives. The Digital Duo's summary of
firewalls is on Show No. 405 at http://www.digitalduo.com/405_dig.html.
Building a Firewall: (Some are
free)
Inoculate!:
Note that Adaptec's
GoBack is designed for recovering a hard drive that has been damaged.
Buildin' a Firewall
It was a bright, sunny day in southern California, a day like any other. A
woman – we'll call her Alice – had left her house to run a few errands,
leaving her computer and Web connection on. When she returned home, something
very unusual was happening. Out of the corner of her eye, she noticed that the
cursor on her PC was moving on it's own! As she rushed over, she saw the
cursor open up her tax files and start scrolling through the documents as if
searching for something. Then, with a terrible clarity it dawned on her –
the invisible hand was after the one thing she couldn't live without, the
thing that identified her very being – her social security number! Aaahhhh!
It's a pretty scary
thought, but not an unusual occurrence. These kinds of break-ins can easily
happen if you don't protect yourself. Along with all the wonderful things the
Web has brought us, it has also ushered in an era of increased security risks
arising from no-goodniks seeking your personal info. Most of the evildoers –
aptly called "crackers" – break into your machine and use it as a
launching pad for large-scale attacks against organizations like NASA or the
IRS. But some crackers will come after your personal data. Luckily, there are
some software products available that you can use to protect yourself against
most of these ne'er-do-wells.
The most common
protection comes from something called a "firewall." A firewall is a
barrier between your computer and the outside world. There are both hardware
and software firewalls available, but in this segment we look at a few
software firewalls. The hardware variety is complex and expensive and doesn't
make sense for the average home or small business computer user.
Your computer is far
more likely to be at risk if you have an "always-on" connection like
cable or DSL. That's because the longer you're online, the more time a cracker
has to figure out how to sneak onto your system. Dial-up connections aren't
immune to crackers either – they just present fewer opportunities.
We looked at three
firewall packages: Norton's Internet Security 2001, Network Ice's BlackICE
Defender and Zone Labs' ZoneAlarm. There are small differences between them,
but they all perform the main task very well – protecting your computer. All
three packages let you choose how secure your firewall will be: low, medium or
high security. A low security filter will let you perform most types of
Internet activity like e-mail or Web surfing without interfering. But a low
filter might try to stop you from downloading a program from the Net. A high
security filter will alert you about anything having to do with Internet
activity on your computer – like e-mail, or Web surfing, or downloading a
program from the Net. This can be as annoying as it is helpful. It just
depends on how paranoid you want or need to be. BlackICE gives you more
options that the other two packages: Trusting, Cautious, Nervous and Paranoid.
There is no one best solution, each package has its strengths.
ZoneAlarm's major
strength is that it's free to consumers and is easy to set up. You don't have
to struggle with advanced settings – although you can. Sometimes its
warnings pop up too frequently, requiring you to click the "close"
box again and again – which, again, can be very annoying.
BlackICE isn't free.
It costs $40 and is suited for the more technically inclined. You'll feel like
a master spy when you use it. It lets you see exactly who or what is probing
your computer. Susie was surprised to find out that her machine was constantly
being probed by outsiders. Someone even checked to see if she had a RAT or
Remote Access Trojan horse on her computer. Now that's pretty scary. A RAT
basically gives a cracker total control over your machine. So, you ask, why
would anyone have a RAT on their machine? RATs were originally designed for IT
folks in a corporate setting to be able to fix your computer remotely.
Unfortunately RATs are being put to use in far less benign ways. A cracker,
disguising him-/herself as a Microsoft tech person, might send you an e-mail
with an innocent looking program attached. When you install this program,
often just by clicking on it, it installs the RAT on your machine and the
cracker has total access to your life. Ack!
Firewalls are also
very good to acquire if you have a home network. When you share printers and
files on your home network, you open yourself up to enormous security risks
from the outside. Basically you're inviting anyone and everyone to share your
printers and files. Most home networking kits don't include firewalls,
probably because the companies that produce them don't want to acknowledge
their vulnerability. That might discourage the unwary consumer from buying
their product.
One of the cooler
features in Norton's firewall package is ad-blocking. The package includes a
program that removes virtually all of the ad banners from Web pages – which
has the added advantage of speeding up Web surfing considerably, without
messing up page layout. Norton's package also lets you hide yourself from Web
sites so they can't keep track of where you're coming from or where you're
going. However Norton's firewall has a tricky interface and costs a hefty $80.
If you'd like a
quick, free, vulnerability checkup, visit the Web site GRC.com and click a
button called "Shields Up!". Watch as it probes your machine and
tells you how vulnerable you are and what you need for protection. Then maybe
you'll be convinced that you shouldn't go surfing without a firewall.
Save/Delete Steve: He
has ZoneAlarm on his machine and it's stopped quite a few intruders. Big Save.
The others are fine too so Save them. Susie: Save ZoneAlarm for people who
want a simple free program. Save BlackICE Defender for folks who are a little
more tech-savvy, and Norton's Internet Security 2001 for about everyone else
Inoculate! What's
scarier than a cracker? More ubiquitous than a hacker? More infectious than
the common cold? A computer virus! If the Love Bug virus has taught us
anything, it is that the Net is a dangerous place – and any bug worth its
code can spread to epidemic proportions in less time than it takes for you to
get over a case of the flu!
Computer viruses are
little, tiny programs that are disguised as something innocuous or are
completely hidden within programs, documents, or floppies. You catch a virus
when an infected e-mail, document, disk or program is loaded (down- or up-)
onto your computer. Once loaded, the virus delivers its payload. The payload
can be fun and innocent – like playing little songs for you once a day. Or
the payload can be catastrophic – like wiping out your entire hard drive,
and those of your closest friends. It's a wild, woolly, virus-filled Web out
there, and we're here to help.
One way to keep
viruses out is to screen everything that comes into your computer: e-mails,
floppies, zip disks and the like. But to do that well you need anti-virus
software. The top two products on the market are McAfee's Virus Scan and
Norton AntiVirus. . They're pretty similar. They will keep you safe from most
bugs. They'll go online and retrieve updated vaccines to protect you from the
newest creations by the mostly disaffected youth who write the virulent code.
But beware: there is a time lag between the moment a new virus hits the info
highway and when the cure is available. You need to be dogged and
ever-vigilant in your immunization strategy.
Many people are under
the impression that an anti-virus program protects them all the time. But
that's not the case. E-mail is an especially effective transport mode for
viruses to jump from host to host. The first rule of virus-prevention is:
Never open an e-mail attachment from someone you don't know. And, in light of
the Love Bug you'd also better be careful with attachments from someone you do
know! The Love Bug spread itself through e-mail, replicating itself when the
mail was opened, and then sending its clones out to everyone in the newly
infected computer's e-mail address book. So you got it, and so did Grandma,
your niece, your cousin and all your colleagues. The lesson? Unless you're
expecting an attachment, don't open it. Worst case you'll have to send a
letter back to your friend to make sure that the attachment is legit.
For example, Susie
got an e-mail from a PR guy that stated "I LOVE YOU" in the subject
line. Either that guy had stepped way over the line of protocol and was about
to loose his job, or his e-mail contained a possible virus. Luckily Susie
deleted it – saving herself from infection by what soon became known as the
worst virus infestation ever: the Love Bug.
If you choose to
install anti-virus software, make sure you understand how it works. Steve had
Norton AntiVirus on his machine for months but didn't realize that the program
was not checking for virus updates regularly. That's something you should do
every week or so.
No matter how
vigilant you are, and no matter how fast the anti-virus software folks work,
there will always be new, sneakier, better viruses. Companies like IBM and
Symantec (the maker of Norton AntiVirus) are developing something called the
Digital Immune System. This program would automatically detect when you've
been infected by a virus. Like the real virus hunters, it would isolate a
virus sample, send a copy of it to a central server which would automatically
create a cure and send it back – much like the CDC operates (Yeah, right.).
But that magic bullet is still a long way off.
In addition to using
anti-virus software, you should also back-up your system every month or so,
just to be safe. Another protective measure you can take is to use software
packages on the market like Adaptec's GoBack. It isn't an official anti-virus
program but it does let you reset your computer to go back to a previous state
– say, the state it was in the morning before you were infected. That way
you can recover most of your work and all of your computer if you happen to
get broad-sided by a bug with less-than-loving intentions.
So get yourself some
anti-virus software, keep it updated, and suspect everybody. Remember Typhoid
Mary? Even the innocent can spread bugs.
Bob Jensen's email message to the
Digital Duo on January 8, 2001
In your Show Number 405 and other shows
you repeatedly warn about opening email attachments or other files that may
contain viruses (especially macro viruses. However, you never mentioned
that the most common files (DOC files, XLS files, etc.) can be safely opened in
JASC's QuickView Plus (which is a very cheap software item from the same company
that developed Paint Shop Pro). Go to http://www.jasc.com/
($49). QuickView Plus is very easy to both install and run. Among
other things it lets you read your email attachments without virus risks.
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Now you CAN open virtually any
file and email attachment with Quick View Plus – the easy way to view
virtually any file.
- Saves money and time –
views files from programs you don't have installed on your computer
- Views email attachments
instantly, whether you have the original application or not
- Views graphics, documents,
spreadsheets, databases, presentations, zip files, and more
- Gives you access to over 200
Windows, DOS, Macintosh, and Internet file types
- Supports new formats
including Visio, Project, Word, Excel, and Powerpoint 2000
- Includes built-in zip
program – no need to buy a separate zip program
- Views virtually any file –
saves time and money
- Views email attachments
instantly
- Maintains formatting of the
original document
- Protects against troublesome
macro viruses
- Prints files with fully
formatted output
- Cuts the cost of buying
expensive software just to view files
- Integrates with popular
browsers and email programs
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Bob Jensen's threads on networking and computer security are at http://www.trinity.edu/rjensen/ecommerce/000start.htm#SpecialSection
Bob Jensen's Threads are at http://www.trinity.edu/rjensen/threads.htm
Bob Jensen's Homepage is at http://www.trinity.edu/rjensen/