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Seven tips for securing your organization´s network from spam and email viruses
By:Todd Green
Seven tips for securing your organization´s network from spam and email viruses
Providing security against email related threats has become a burden for most IT professionals in 2006. According to a recent study by Postini, spam and email viruses now make up to 80% of all emails sent out as compared to 50% in 2000. As a result, IT professionals now face a tougher challenge in providing network security for this amount of spam. IT professionals also have the disadvantage of defending against new forms of email threats such as spam zombies, directory harvest attacks, mass mailing trojans, as well as the latest email virus.
In this article, I have listed the seven most effective spam fighting tips for organizations with in-house mail servers. These seven tips are proven techniques I have used for my customers, partners and associates who wish to tighten their perimeter (network) security.
1. Firewall:
A firewall is your first line of defense against hackers, crackers, and spammers. Without a firewall, your network is a disaster waiting to happen and could give any novice hacker free reign over your network. If your organization has multiple Internet users, this tool is essential for securing your network.
2. Block Port 25:
On your firewall, allow outbound traffic on TCP port 25 for all mail servers. Block traffic on outbound TCP port 25 for all other computers and servers. On the Internet, TCP port 25 is used for email traffic through SMTP (Simple Mail Transport Protocol). Blocking this port is a good security practice and prevents mass mailing worms and spam zombies from sending mail from your users’ computers.
3. Managed Email Filtering:
Consider using a managed filtering solution such as Postini, Brightmail, or SpamSoap. Managed Email Filtering services quarantine spam, viruses, and email threats before reaching the email servers on your network. In comparison to desktop filters and server appliances, managed filtering services provide superior perimeter (network) protection by preventing delivery of spam and viruses to your network and servers.
4. Check Relay Setting:
A mail server’s relay setting controls which computers and servers are able to send SMTP email on your organization’s behalf. Check your settings and limit the IP address range to email users on your local network. Some mail servers have settings to limit email relay through authentication. If authentication-based relay is available, setup and configure it too. NOTE: If the relay is not set properly, spammers will be able to send email from your mail server. This exploit is commonly known as an “Open Relay” or a “Spam Relay.” Use the Open Relay test at http://www.abuse.net/relay.htm to check if spammers can relay mail from your server.
5. Black Lists:
Setup your mail server(s) with a black list. A black list (black hole list) is a database or listing of known spam sources. Most modern email servers can be configured to query inbound email against online blacklists. Messages originating from these sources can then be blocked. I recommend configuring your email server with SpamHaus blacklist. Spamhaus.org is an excellent free service to use. Some other good blacklists are DBSL and SpamCop.
6. Reverse DNS:
Reverse DNS (rDNS) associates an IP Address with a Domain Name. Most mail servers, as an anti-spam feature, often use a reverse DNS lookup to compare an email address domain name with its IP address. If the IP address found from the rDNS lookup does not match the domain name, it is probably spam. If you haven’t done so, setup and configure reverse DNS records on your DNS server.
7. Anti-Virus Scan:
There are many tools that provide adequate anti-virus protection for desktops at the workplace. Most anti-virus software is good at detecting viral threats that proliferate email spam such as mass mailing worms, trojans, and directory harvesters. Large organizations might want to use enterprise anti-spam software with management and monitoring tools that will allow tracking of network virus outbreaks.
Recommended Links:
- SPAM-X [Postini service – managed filtering, 1 to 500 users]
- http://www.postini.com [Postini service – managed filtering, 500+ users]
- http://www.spamhaus.org [Blacklist]
- http://www.dbsl.org [Blacklist]
- http://www.spamcop.net [Blacklist]
- http://www.abuse.net/relay.htm [Open relay test]
- http://www.dnsreport.com [DNS report/open relay test]
- http://www.dnsstuff.com [Spam database lookup and open relay test]
- http://www.cnn.com/2004/TECH/ptech/02/17/spam.zombies.ap [Spam Zombie Article]
Email viruses and related threats delivered through spam have cost businesses billions of dollars in expenses and lost productivity. Each spam email sent or received from your domain costs your organization money and bandwidth. By implementing these seven tips, your organization can reduce spam and recover costs.
This article: © Copyright 2006 Todd Green and free for republishing.
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Article keywords: Spam, Spam Filter, Anti-Spam, Network Security, Network
Article Source: http://www.articles2k.com
About the author: Todd Green is a partner of a Memphis-based IT consulting firm. He has over fourteen years’ experience in the field of Information Technology and has managed security on many corporate networks over the years. He is the owner of SPAM-X, a Postini reseller (www.spam-x.com) and a partner for Postini’s preemptive spam and virus filtering service.
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| Top Spam Articles |
- 1). Free Spam Blockers By : Matt Garrett
Remember when spam was just another horrible thing you would never eat? And then you grew up a little and spam became the lyrics to a great Monty Python song. And now spam is something to avoid at all costs. Or, in the case of free spam blockers, at no cost at all. Everything is better when it’s free, right? Such is the case with blocking out annoying spam from your email account, too.
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- 2). Save Time, Money and Hassle - Stop Spam By : Justin Brown
Spam can be an absolute nightmare, and one that seems to spiral out of control in some of my email accounts. If i've been away for a few days and haven't had a chance to check my emails, I dread having to open up my email client when I get back online in anticipation of hundreds or thousands of spam emails.
Although I simply delete these emails, for some, they seem legitimate messages that can often cause the recipient to become the subject of a fraudulent activity.
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- 3). Antispam Organization Out There That's Fighting For You By : Robert Michael
There's an antispam organization out there that's fighting for you and could use your help.
CAUCE, the Coalition Against Unsolicited Commercial E-mail, is an all-volunteer global entity that began as SPAM-LAW, a group brought together for discussion only. They put all their efforts into getting legislation passed that would help stop and penalize spam.
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- 5). Real Businesses Send Spam, Too! By : Jerry Weinstock
Unsolicited Commercial Email or Spam has grown at epidemic proportions. It is rapidly becoming the number one problem that Information Technology departments deal with on a day-to-day basis, surpassing computer viruses. The volume and percentage of unwanted email received in business and personal email inboxes is starting to overwhelm and drown out legitimate email.
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- 6). Spam Filter - Bayesian Filter to Fight back Spammers By : Micky Sing
The most prolific and path breaking innovation of last century had been the developments in the communication field. It literally changed the business working, product marketing, support services and most importantly, the advertisement campaigns.
But just like all goods things comes with a price, so was the communication. It brought in the problems of Spam Emails.
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- 7). How Do Anti Spam Solutions Work? By : Paton Jackson
We have all suffered from these annoying dangerous spam emails. Most of us still do. There are excellent anti spam solutions in the market, there is no reason to tolerate this no more.
To understand the solution we must first understand the problem. So, what is this spam email? Spam is unsolicited, unwanted, irrelevant or inappropriate email. Spam email is mostly used for commercial purposes.
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- 8). How to Reduce Spam in Your Inbox and Enhance Your Email Security By : Richard Rogers
Spam is the internet’s equivalent of junk mail. Spam is defined as an e-mail message sent to people without their consent or permission. Addresses of recipients are often harvested from Usenet postings or web pages, obtained from databases, or simply guessed by using common names and domains.
Spam is sent to promote practically any product or service ranging from “Adult” products to logo design for websites.
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- 9). Seven tips for securing your organization´s network from spam and email viruses By : Todd Green
Seven tips for securing your organization´s network from spam and email viruses
Providing security against email related threats has become a burden for most IT professionals in 2006. According to a recent study by Postini, spam and email viruses now make up to 80% of all emails sent out as compared to 50% in 2000. As a result, IT professionals now face a tougher challenge in providing network security for this amount of spam.
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- 10). Email Anti Spam And Virus Protection For Businesses - There Is Hope By : John Tourloukis
With anti spam vendors offering low cost licensing, businesses can now afford advanced email spam and virus protection with a simple to use interface at a much lower cost. The great thing about technology is that as it evolves it gets faster, additional features and economical. Over the past few years the same evolution has taken place with anti spam technology and services.
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| New Spam Articles |
- 1). Identifying Spam When it Arrives By : Keith Londrie
Most of us have opened our email program and found, alongside correspondence from people that we know, offers for products from commercial web sites. Some of these emails we expect. We have asked to be notified of sales and other opportunities or joined a mailing list offered by the company.
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- 2). Save Time, Money and Hassle - Stop Spam By : Justin Brown
Spam can be an absolute nightmare, and one that seems to spiral out of control in some of my email accounts. If i've been away for a few days and haven't had a chance to check my emails, I dread having to open up my email client when I get back online in anticipation of hundreds or thousands of spam emails.
Although I simply delete these emails, for some, they seem legitimate messages that can often cause the recipient to become the subject of a fraudulent activity.
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- 3). A Quick Look At Email Spam Filters By : Oliver Turner
You must be eagerly finding for a way out to stop receiving Spam mails in your inbox. Take a quick look at email spam filters to get some idea on how to check spam. There are a number of email spam filters that you can use in your computer. For official purposes, you have anti server software spam where the spam filter is located in the server level to trap all email spam.
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- 4). An Introduction To Spam Filters By : Peter Emerson
Using spam filters is another very effective way of combating spam or junk mail. These programs use some keywords like ‘guaranteed’, ‘free’, etc and block any email with those words in them. But this has the disadvantage of sometimes blocking even important mails from your contacts and preventing those senders from sending mails to your address again.
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- 5). What Is Spam? By : Daniel J.Fox
You have probably seen an increase in the amount of junk mail which shows up in your email box, or on your favorite newsgroup. The activities of a small number of people are becoming a bigger problem for the Internet.
Chain letters that ask for money, whether for reports or just straight up, are illegal in the US whether they are in postal mail or e-mail.
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- 6). Fighting Spam! By : Darry J.Oswald
It's been nearly a decade since spammers and their enemies begun evolving competitively. As with the classic cheetah/gazelle model originally formulated by Darwin, each time one group becomes a little faster or more agile, its adversaries develop traits for outwitting and outrunning it.
In addition to wasting people's time with unwanted e-mail, spam also eats up a lot of network bandwidth.
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- 7). Two Main Groups Of Spam! By : Camry James
There are two main types of spam, and they have different effects on Internet users. Cancellable Usenet spam is a single message sent to 20 or more Usenet newsgroups. (Through long experience, Usenet users have found that any message posted to so many newsgroups is often not relevant to most or all of them.) Usenet spam is aimed at lurkers, people who read newsgroups but rarely or never post and give their address away.
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- 8). Antispam. Aren't We All! Don't You Just Hate It? By : Robert Michael
Antispam. Aren't we all! Don't you just hate it? You've got enough to do without having to sift through a bunch of worthless, or worse yet, offensive junk e-mails in your Inbox.
So what can be done about it? What antispam procedures and software really work?
Spam filtering software is the first stop in your antispam campaign, but in some ways it's the easiest to subvert.
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- 9). Everybody Hates Spam By : Jay Ashley
There is nothing like checking your email only to find out that your inbox is swamped with unsolicited message from people you do not know. No you’re not interested to buy dog food, beauty products, slimming pills, plants, or software! But still, you get these irritating emails.
Spam, this tiny four letter word has annoyed millions of people around the world.
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- 10). The Spamming Trap For Online Business Beginners By : Rami Doleh
People who begin their online business ventures would naturally be unaware of many of the internet business rules, protocols and etiquettes. Yet, as in any law, the internet law does not forgive for ignorance. One of the most important issues that are governed by many controls over the internet is Spamming.
A beginner in online business can very easily fall unintentionally into the spamming trap while conducting internet marketing activity to promote his/her business.
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