Month: February 2011

Wake a host (wake on lan) from dd-wrt

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WOL through Telnet/SSH

Note: This is the preferred method to send WOL magic packets remotely.

If you have local or remote Telnet/SSH access to your router, you
can wake up a machine on the LAN by using the following command:

[ccNe_bash]
/usr/sbin/wol -i 192.168.1.255 -p PP AA:BB:CC:DD:EE:FF
[/ccNe_bash]

Note that the full path to “/usr/sbin/wol” is important. Simply “wol” will not work.

Substitute AA:BB:CC:DD:EE:FF with the actual MAC address of the computer which you wish to boot remotely. Likewise, replace 192.168.1.255
with the actual broadcast address of the network (192.168.1.255 is the
broadcast address when the machine has an IP of 192.168.1.x and subnet
mask of 255.255.255.0). Replace “PP” with the port number your machine
listens on (usually 7 or 9).

Digitally signing email or documents.

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What are email
certificates used for?

Email certificates provide the strongest levels of
confidentiality and security for your electronic communications by
allowing you to digitally sign and encrypt your mail and attachments.
Encryption means that only your intended recipient will be able to
read the mail while digitally signing allows them to confirm you as
the sender and verify the message was not tampered with en route.

How to obtain one?

There are many sources offering certificates for digitally
signing of email. Many of them are commercial some of them are free.
If you’d like to test this feature Comodo offers a free certificate
for personal use.

Go to
http://www.comodo.com/home/email-security/free-email-certificate.php
and click on Free Download

Fill out all the details
and soon you will receive the certificate by email.

How to install one?

This is how it is installed in
Mozilla Thunderbird running on Linux. No dobt the procedure might
differ on different systems and/or email clients.

After install the certificate is
available in Mozilla Firefox but not Thunderbird, so it needs to be
exported from Firefox and imported inside Thunderbird.

  1. Go to
    Prefferences->Advanced->View certificates

  2. Click on the certificate
    (it’s on the     Your certificates tab)
    and click     Backup

  3. Save the certificate
    somewhere     on your
    computer. It’s a good ideea to keep a copy of your certificate for
    future reference and so you can password protect it so it won’t be
    possible to be imported without knowing this password. (this will
    prevent unauthorized persons from posing as you using a stolen
    certificate backup)

  4. Open Thunderbird.. Go to
    Account settings=>Security (under
    the account you created the certificate for)

  5. Go to View
    Certificates and click import    .
    Locate the certificate you exported above and import it. You will
    have to type the password you entered earlier.

The above procedure will no doubt
be different across operating systems and email clients but the basic
steps should be the same. For example it’s possible that if you use
Outlook and Internet Explorer the certificate will be already
installed in both without requiring extra import/export.

Other certifcate
providers:

  • http://www.instantssl.com/ssl-certificate-products/free-email-certificate.html

  • http://www.verisign.com/authentication/digital-id/index.html

  • http://www.pgptrustcenter.com/digital-certificate-solutions