Chapter 1: Product Features
June 30, 2008 AT Commands Reference Manual 1-9
There are two options for valid closing of a socket, opened in Online Data Mode, when G24 is in
PREMUX state:
Switch G24 to pseudo-command mode and enter +MIPCLOSE command with opened in
Online Data Mode Socket ID.
Disable DTR line on RS232 communication port in case of A&D2 or AT&D3 parameter
configuration.
When G24 is in MUX state, change of DTR or software DTR state on ODM MUX channel closes
ODM session in case of A&D1, A&D2 or AT&D3.
When an error occurred with the socket, opened in Online Data Mode, the socket closes
automatically and +MIPSTAT unsolicited response is being sent to terminal (see “+MIP STAT,
Status Report” on page 3-408).
SSL
General Description
SSL (Secure Socket Layer) and its successor TLS (Transport Layer Security) are cryptographic
protocols which provide endpoint authentication and communication privacy over the TCP / IP.
There are slight differences between SSL 3.0 and TLS 1.0, but the protocol remains substantially
the same. The term "SSL" as used here applies to both protocols unless clarified by context.
Cipher Suite
Cipher Suite is a set of cryptographic algorithms. A cipher suite specifies one algorithm for each
of the following tasks: Key exchange, Bulk encryption and Message authentication. For example,
Cipher Suite TLS_RSA_WITH_RC4_128_MD5 specifies RSA as key exchange algorithm, RC4
with key length 128 bit as a stream cipher algorithm, to encrypt data transfer after handshake, and
MD5 as algorithm for SSL message authentication.
The G24 SSL feature supports the following Cipher Suites (listed in order of the preference):
TLS_RSA_WITH_3DES_EDE_CBC_SHA
TLS_RSA_WITH_RC4_128_MD5
TLS_RSA_WITH_RC4_128_SHA
TLS_RSA_EXPORT_WITH_RC4_40_MD5
TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA
TLS_RSA_WITH_NULL_MD5
Certificate expiration time
In order to check if SSL Certificate has expired, G24 uses internal clock. Some cellular operators
support automatic time synchronization, so the G24 internal clock synchronizes automatically. In
case the cellular operator does not support such feature, user should manually set G24 internal
clock using +CCLK AT command. Since the clock is reset when the power to G24 is cut, the
current time should be updated after G24 is powered up.
Features and Benefits
The TCP/UDP IP feature provides the terminal with the following benefits: