Hardware password search

Coding boards controlled through the SFPTotal command protocol support hardware password searches, allowing a wide range of password values to be checked at high speed.

For details about the purpose and syntax of the control commands, see SFPTotal protocol commands.

During a hardware password search, the coding board does not spend time exchanging data with the application. It enters the password, writes a check word and verifies the write result on its own.

Search speed

You can change the search speed by configuring the coding board's inter-block delay and data bus clock frequency before starting.

Set the data bus clock frequency to 100,000 Hz.

I2CRATE=12

Set the inter-block delay to 16 ms

I2CPAUSE=10

Speed limitations

For a successful search, the operation speed and inter-block delay must give the transceiver enough time to save changes while allowing it to continue communicating and processing data bus events.

An excessively high write speed may interrupt the transceiver's internal procedure for saving changes. As a result, the correct password can be skipped because its effect cannot be verified.

Choose coding board settings that allow the search to continue without being interrupted by data bus error codes.

The module's speed limits depend on its hardware, the quality of its control firmware and the physical erase speed of the target EEPROM/Flash memory.

Check word write location

Use the commands BFCWADR and BFCWOFT to change the default check word write location.

Check word settings for SFP

BFCWADR=A0
BFCWOFT=00

Check word settings for QSFP

BFCWADR=A0
BFCWOFT=80

Settings for writing to page A2h of an SFP transceiver

BFCWADR=A2
BFCWOFT=80

Value ranges

To speed up the search, first check ranges within particular groups of characters represented in the ASCII character table.

Letter range from A to Z

BFSET A2 7B 41414141 5A5A5A5A 41414141

Letter range from a to z

BFSET A2 7B 61616161 7A7A7A7A 61616161

Digit range from 0 to 9

BFSET A2 7B 30303030 39393939 30303030

Symbols, digits and letters

BFSET A2 7B 20202020 7A7A7A7A 20202020

Full range

BFSET A2 7B 00000000 FFFFFFFF 00000000

Starting the search

Starting an SFP+ password search with the standard password entry location

BFCWADR=A0
BFCWOFT=00
BFSET A2 7B 20202020 7A7A7A7A 20202020

Starting an SFP+ password search with a NONSTANDARD password entry location

BFCWADR=A0
BFCWOFT=00
BFSET A2 FC 20202020 7A7A7A7A 20202020

Starting a password search for an XFP transceiver

Before starting a hardware password search for XFP or QSFP modules, set the appropriate MODSEL/MODDESEL jumper on the device board.

BFCWADR=A0
BFCWOFT=94
BFSET A0 7B 20202020 7A7A7A7A 20202020

Search example

Hardware search log for an SFP+ transceiver when connected to the coding board through PuTTY

# Set the clock frequency and delay
I2CRATE=12
I2CPAUSE=05

# Check word entry location
BFCWADR=A0
BFCWOFT=00

# Enable command echo
CLI=1

# Search the specified range, entering the password at A2 offset FC
BFSET A2 FC 84720000 8472FFFF 84720000
Device=A2
Offset=FC
From    84 72 00 00
To      84 72 FF FF
Start   84 72 00 00


FOUND: 84 72 84 00


 STOP
Device=A2
Offset=FC
From    84 72 00 00
To      84 72 FF FF
Current 84 72 84 00

Search result: 84728400

Note

Before running the search, prepare the configuration and hardware search commands in a text editor to avoid possible mistakes.