Category Archives: Computer Security

Computer Security related articles.

My Wireless Network Doesn’t Work When the Baby is Sleeping

Having a baby could affect your wireless communication?

Yes. Well, indirectly yes. Who has a baby and a wireless network will most likely have a baby monitor. We all like to spend our time blogging, or browsing the Internet while the baby is asleep, but we couldn’t blog a word if we didn’t keep an eye on the baby.

Many baby monitors will interfere with wireless networks. The wireless connection will work for most of the time and then suddenly it will stop working; after a wile will resume functioning properly. It could work without interruption but slow down transfer rates as network error corrections will be needed more than regularly.

How TO Eliminate Interference Between Baby Monitors and Wireless Networks?

Make sure you verify the band used by the baby monitor is not overlapping with the wireless band. If it does, you can change the channel on your Baby Monitor. How do you know if it overlaps? Read the instructions manual, and if you don’t have it, just try different channels on your baby monitor until you get a stable connection on your Network.
Another option would be to change the channel used by your wireless access point. If you have an old baby monitor consider buying a newer model, the newer models have less interference with your WiFi Network. I know that this sounds so un-green and consumerist, but I tested this and newer and more expensive models are better protected to interferences.

Is your Toddler Curious about the Little Box on the Wall?

If your child is a toddler he’ll be very curious about the different devices hanging around in your office and he will find your wireless AP. They will try, whenever they have the chance, to press any buttons and pull all the cables. Make sure, when your connection goes off, to check all the connections to the access point and to the modem. Consider to move your devices where your child cannot reach them.

Email address Spoofing – Someone is Using My address to Send Spam

Someone is Using Your Address to Send SPAM

You just got a bounce-back email saying that your email didn’t reach the destination because the recipient doesn’t exist. Nothing unusual, this is something that happens to anybody who is using email regularly; except you didn’t send that email. How could this happen? If you are an email server administrator and many of your users get this kind of bounce-back they all start to complain at once, thinking that your server has been hijacked. What can you do to stop this, and how to reassure your users that you haven’t been hijacked?

Sender Address Forgery known as email address spoofing is not a new technique. It is used for many things from spamming organizations to sending viruses and supporting scamming schemes where the sender fakes his identity.

Effective ways to stop Spammers to Use Your Domain Name

Publish SPF Data
SPF (Sender Policy Framework) is a method that allows you to publish which mail servers are authorized to send email for your domain. SPF uses a DNS record that tells email servers which servers are the servers that are trusted sources of email for the specific domain and how much to trust other sources of email originating from that domain. Destination servers might have the SPF checking implemented or not. Many of the today’s servers are SPF checking enabled.
Destination servers check this record and act in consequence. Anti-spam software on servers receiving emails, score an email based on SPF record and other criteria and accept or reject the email based on the total score. For instance if the SPF record tells that any emails originating from non authorized servers should not be trusted the email gets the necessary points to be treated as SPAM and it gets rejected. If the SPF record treats the non authorized servers neutral the message could pass or could be rejected if other it contains other SPAM characteristics.
Do not publish any email addresses on Web pages. This is the most common place for spammers to get valid email addresses and use them to forge email messages

If your company runs its own mail server configure it to ignore email sent to non-existent addresses in your domain. If your server sends a non-delivery report you reveal to a spammer valid addresses in your domain (the ones that don’t send NDRs). This attracts spam to those addresses. You waste bandwidth. The most common reason to send NDR’s for non-existent addresses is to let people know that they misspelled the address. Miss-addressed email can get lost easier.

If your domain gets blacklisted because of spoofing you have to contact the list which blacklisted you and show the Administrator what you did to correct the problem. This is very unlikely since the sender usually spoofs only the email sender and not the server’s address. A blacklist Admin should be able to figure out this.

Preventing Domain Name Spam

What is domain name spam?
Domain Name Spam is a spamming technique where the sender only knows the domain name and he doesn’t have any valid email address in the domain. The technique involves sending emails to all the possible combinations or to a nicely crafted dictionary. The most common addresses in such a dictionary are:
• info@
• mail@
• sales@
• contact@
• contacts@
• root@
• help@
• home@
• contactus@
• enquiries@
• webmaster@
• hr
• shipping
The generic list is actually very long but I won’t include here all of the addresses.
Other possible entries in the dictionary are common names and different combination of these names. Let’s take for instance the name John Doe. A few possible combinations and the most used are: john.doe@company.com, j.doe@company.com, john.d@company.com, johndoe@company.com, etc…
What can you do to discourage and stop this kind of spam?
Set up your email server so it will not accept too many emails from the same server within a specified time frame.
Do not send NDR for unknown recipients, this will inform the attacker about the invalidity of those addresses, this is good information for a spammer. The disadvantage with this is that misspells of an address from a legitimate sender will not inform them about the error.

Use less commonly used prefixes for your email addresses.
Instead of “info@yoursite.com” use “askaquestion@yoursite.com”.
Instead of “webmaster@yoursite.com” use “yourname@yoursite.com”.
Instead of “help@yoursite.com” use “problem@yoursite.com”.
You do want to still keep your email addresses professional and to make sense to your customers. An email address like Egfa13wge2@yoursite.com will fool domain name spammers, but customers will be tempted to delete the email when they see such an email address in the “To” field of their email.
Also, don’t forget that many domain name spammers hope you have your catch-all turned on. This means that even sending an email to “any-address@yoursite.com” will end up in the admin’s mailbox even if that email address doesn’t exist. Unless you have a need for your catch-all to be turned on, you should have it turned off by default.

Anti Spam Techniques – How to Prevent and Stop Email SPAM

Anti Spam

Good Policies and Habits

Email SPAM has become one of the worst annoying things associated to Internet communication.
There are many things you can do to avoid SPAM. There are preventive measures and there are remedial actions. Between the two of them, the preventive actions are the best because have the least impact on you. Preventing SPAM costs less than removing and saves your precious time.

Anti spam Laws

Many of the developed countries have anti spam laws, that are meant to stop unsolicited email messages. Having laws against spam is great and it is a great step forward, but as an end user and an email user, you have to understand that it is your responsibility to prevent spam and to act responsible when using the email. In some countries the anti spam legislation is not very effective, so people will still send unsolicited messages, crafted so they will abide the law. Because email is using the Internet, it is basically open to abuse from any country without specific legislation.

What Can You Do to Prevent Email SPAM?

Spam Preventing Strategies and Behavior

First of all do not give your email address to dubious sites or people you don’t trust.
If you need to subscribe to various doubtful sites you need to create a second email account that you can easily discard when the SPAM level becomes intolerable.
Even better, have three accounts. At least one account should be dispensable.
Do not publish your email address on your web-pages. These are regularly scanned by spammers to harvest addresses. Use web – forms instead. These forms will allow people to send you emails but they will hide your address from spammers’ eyes.
When filling registration forms online, look for the box that requests future offers, or subscription to news-letters and select or deselect as needed.
Do not forward chain letters or, if you really need to, the article Stop Chain Letters – Anti Spam talks about how to prevent spammers to harvest addresses from your email correspondence.
BCC is your friend against spammers. When sending messages to many recipients at once, use BCC to insert all the destination addresses. This field (blind carbon copy) hides the addresses of your recipients. Read this article for more information.
Your work email is only for work. Do not mix your work emails with the personal ones, this is actually part of the Anti Spam IT policy of many companies.
Many Government Agencies and Institutions use email as a way of communication. You should use a special email account only for this kind of communication. This might even be a free account like “Gmail” or “Live” accounts. This will avoid getting this important account spammed.
If you don’t know the sender of an unsolicited email, delete the message immediately.
Never buy from unsolicited emails. You might get scammed and end up on a spammers’ list.
Do not answer spam messages and do not click on any links in spam messages. The “Unsubscribe” links on spam messages are just a way to trick you to confirm the spammer that he has a good address.
Generally speaking, reduce the exposure of your email address in any way.
Use dispensable accounts for dangerous activities.

What can you do to remove SPAM from your mailbox?

Personal Anti Spam Software

Use user level anti spam software. If you use Microsoft Outlook keep you Ms Office up to date as the integrated Junk Filter filters most of the unrequested emails. Some of the most known personal anti spam software are: Norton Anti Spam, Mailwasher, (free version available), Vanquish Personal Anti-Spam, Spam Bully, Spam Buster, SpamFighter Pro, Personal Antispam for Mac, etc…

Corporate Anti Spam Solutions

Speak to your Network Administrator about a corporate anti spam solution. A free anti spam solution that will work great in a corporate environment is Spamassassin. Other commercial anti spam solutions include Mailwasher the server edition, Trend Micro, GFI MailEssentials, Exclaimer Anti-spam, SPAMfighter Exchange Module, SpamTitan ISO as software solutions. There are also anti spam appliances such as MailFoundry, iForce Mail Firewall, Barracuda Networks, Roaring Penguin CanIt, Astaro, SpamKiller Appliances, Fortimail, etc…

Hosted Anti Spam Solutions

Hosted anti spam solutions have become widely adopted because of the convenience and the near to zero administration involvement. These are anti-spam servers that will filter the junk email before delivering to you mailbox or your server depending on the case. Some great hosted anti spam services are: Hosted CanIt anti-spam service, (Roaring Penguin), GFI MAX MailProtection, Symantec Cloud, Barracuda Networks, Google’s Postini, etc…

Solicited Messages can Become Spammy

Unsubscribe from any news-letter that becomes annoying. Sometimes you subscribe to a newsletter and it is fine for a while and in time they decide to send you more emails. I was surprised by the number of people that tolerate unneeded messages and do not unsubscribe. As underlined above do not unsubscribe to unsolicited email messages, you will only make it worse.
As a last resource give up the email account and create a new one. Inform all your friends about your new address and set an auto responder informing about your new address. Spam emails are automated there isn’t a person who is reading the bounce backs or replies, therefore an auto responder with the new address will be only read by real people.

What can you do to help the fight anti spam?

Spread the word. Give your friends the address of this page.
Translate this page in other languages.
Comment on the bottom of the page with other suggestions.
Publish a link to this article on your website or give us your thoughts about other anti spam solutions.