Chapter 3 Configuring the Cisco ATA for H.323

Configuring the Cisco ATA Using a TFTP Server

Using the EncryptKey Parameter and cfgfmt Tool

The EncryptKey parameter encrypts binary files being transferred over TFTP. You can change this key for each Cisco ATA, so that only one specific Cisco ATA can decode the information.

By default, the Cisco ATA-specific ata<macaddress> configuration file is not encrypted. If encryption is required, however, you must manually configure the EncryptKey parameter before you boot up the Cisco ATA so that the TFTP method is secure. Use either the voice configuration menu (see the “Voice Configuration Menu” section on page 3-15) or the Cisco ATA web configuration page (see the “Cisco ATA Web Configuration Page” section on page 3-18) to configure the EncryptKey parameter.

Note Because the factory-fresh ATA cannot accept encrypted configuration files, the first unencrypted file, if intercepted, can easily be read. (You would still have to know the data structure format in order to decode the binary information from the unencrypted file.) Therefore, the new encryption key in the unencrypted file can be compromised.

Set the EncryptKey parameter to a nonzero value. When this value is nonzero, the Cisco ATA assumes that the binary configuration file on the TFTP server is to be encrypted with this key by means of the RC4 cipher algorithm. The Cisco ATA will use this key to decrypt the configuration file.

The Cisco ATA EncryptKey parameter and the encryption key used in the cfgfmt tool command syntax must match.

Note For security reasons, Cisco recommends that you set the UIPassword parameter (if desired) in the configuration file and not by using one of the manual configuration methods.

The cfgfmt.exe syntax affects how the EncryptKey parameter is used, as shown in the following examples. In these examples, input_text is the ata<macaddress>.txt file that you will convert to binary to create the ata<macaddress> configuration file for the Cisco ATA; output_binary is that binary ata<macaddress> file, and Secret is the encryption key.

Syntax examples

•cfgfmt -tpTagFileinput-text-file output-binary-file

If input-text-file sets the Cisco ATA EncryptKey parameter to 0, then output-binary-file is not encrypted. If the input-text-file sets EncryptKey to a non-zero value, then output-binary-file is encrypted with that value.

•cfgfmt -eSecret -tpTagFileinput-text-file output-binary-file

If the Cisco ATA EncryptKey parameter has the value of 0 or is not included in input-text-file, the Secret is used to encrypt the output-binary-file. If input-text-file sets the Cisco ATA EncryptKey parameter to a nonzero value and the -e option is used, then output-binary-file is encrypted with the EncryptKey parameter set in input-text-file and Secret is ignored.

•cfgfmt -E -tpTagFileinput-text-file output-binary-file

The -E (uppercase) option means that any value specified for the Cisco ATA EncryptKey parameter in input-text-file is ignored. However, because Secret is not specified in this example, output-binary-file is not encrypted. Nevertheless, the EncryptKey parameter and its value, if specified in input-file-text, will be included in output-binary-file for possible encryption at a later time.

Cisco ATA 186 and Cisco ATA 188 Analog Telephone Adaptor Administrator’s Guide (H.323)

 

OL-4008-01

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Cisco Systems ATA 188 manual Using the EncryptKey Parameter and cfgfmt Tool, Syntax examples
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ATA 188 specifications

The Cisco Systems ATA 188 is a versatile Analog Telephone Adapter designed to facilitate the integration of traditional telephone systems with Voice over Internet Protocol (VoIP) networks. This device has been key in bridging the gap between legacy telephony and modern IP-based communication, allowing users to leverage their existing analog phones while enjoying the benefits of digital connectivity.

One of the main features of the ATA 188 is its ability to connect regular analog phones to a VoIP network, enabling users to make and receive calls over the internet. This significantly reduces calling costs, especially for long-distance and international calls. The ATA 188 supports two phone lines, allowing simultaneous voice calls. This dual-line capability makes it a suitable choice for small businesses or home offices that require multiple lines without the need for extensive infrastructure.

The device is equipped with various technologies that enhance its functionality. It supports the Session Initiation Protocol (SIP) and H.323, making it compatible with a wide range of VoIP service providers. Additionally, the ATA 188 features Quality of Service (QoS) settings, which prioritize voice traffic over the internet, ensuring clear voice quality without interruptions or delays. This is essential for maintaining a professional communication experience, especially in business environments.

Another characteristic of the ATA 188 is its user-friendly configuration interface. It allows users to easily set up and manage their devices through a web-based portal. The configuration process is straightforward, with options to adjust settings such as codec selection, call features including call waiting, and call forwarding functionalities.

Security is also a priority for the ATA 188, as it provides robust protocols to protect call data. The device supports Secure Real-time Transport Protocol (SRTP) and Transport Layer Security (TLS) to encrypt voice traffic and manage signaling securely. This ensures that sensitive conversations remain confidential.

Overall, the Cisco Systems ATA 188 is a reliable and efficient solution for users looking to transition from traditional telephony to VoIP. Its dual-line capacity, compatibility with multiple VoIP standards, user-friendly configuration, and built-in security features make it a valuable asset for both personal and professional communication solutions. In an ever-evolving telecommunications landscape, the ATA 188 remains a relevant and practical choice for integrating legacy telephony with modern internet-based services.
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