LeechModem
Encyclopedia
LeechModem was a BBS
file transfer protocol client. LeechModem was compatible with protocols like XMODEM
(and YMODEM
), but it would mischievously NAK
the last packet and then abort the file transfer. The user had successfully downloaded the file, but the BBS would mistakenly not count the aborted file transfer against the user's download quota. The user would need to know and input the filesize before the transfer so the client would know when to abort.
Leech-modem was designed by Sam Brown. Leech ZMODEM
was suggested by Sam Brown but written by a long lost friend in Atlanta, GA. Leech ZMODEM
was a LeechModem variant that was compatible with the faster ZMODEM
streaming file-transfer protocol.
Subsequent versions of Leech ZMODEM
were authored by Sam Brown. LeechModem was used successfully for 2-3 years by a small group of people centered in the 408 area code
. It was not until the LeechModem software was leaked that it was discovered and counter-measures were built into BBS
software. Emulex/2 was the first BBS software to support Anti-LeechModem technology. This was because Sam Brown wrote Emulex/2 BBS
software as well. A common method was rounding the file size to the nearest kilobyte, causing the user to be unaware of the exact file size, rendering Leechmodem unusable.
Bulletin board system
A Bulletin Board System, or BBS, is a computer system running software that allows users to connect and log in to the system using a terminal program. Once logged in, a user can perform functions such as uploading and downloading software and data, reading news and bulletins, and exchanging...
file transfer protocol client. LeechModem was compatible with protocols like XMODEM
XMODEM
XMODEM is a simple file transfer protocol developed as a quick hack by Ward Christensen for use in his 1977 MODEM.ASM terminal program. XMODEM became extremely popular in the early bulletin board system market, largely because it was so simple to implement...
(and YMODEM
YMODEM
YMODEM is a protocol for file transfer used between modems. YMODEM was developed by Chuck Forsberg as the successor to XMODEM and MODEM7, and was first implemented in his CP/M YAM program...
), but it would mischievously NAK
NaK
NaK, or sodium-potassium alloy, an alloy, of potassium , and sodium , is usually liquid at room temperature. Various commercial grades are available. NaK is highly reactive with water and may catch fire when exposed to air, so must be handled with special precautions...
the last packet and then abort the file transfer. The user had successfully downloaded the file, but the BBS would mistakenly not count the aborted file transfer against the user's download quota. The user would need to know and input the filesize before the transfer so the client would know when to abort.
Leech-modem was designed by Sam Brown. Leech ZMODEM
ZMODEM
ZMODEM is a file transfer protocol developed by Chuck Forsberg in 1986, in a project funded by Telenet in order to improve file transfers on their X.25 network...
was suggested by Sam Brown but written by a long lost friend in Atlanta, GA. Leech ZMODEM
ZMODEM
ZMODEM is a file transfer protocol developed by Chuck Forsberg in 1986, in a project funded by Telenet in order to improve file transfers on their X.25 network...
was a LeechModem variant that was compatible with the faster ZMODEM
ZMODEM
ZMODEM is a file transfer protocol developed by Chuck Forsberg in 1986, in a project funded by Telenet in order to improve file transfers on their X.25 network...
streaming file-transfer protocol.
Subsequent versions of Leech ZMODEM
ZMODEM
ZMODEM is a file transfer protocol developed by Chuck Forsberg in 1986, in a project funded by Telenet in order to improve file transfers on their X.25 network...
were authored by Sam Brown. LeechModem was used successfully for 2-3 years by a small group of people centered in the 408 area code
Area code 408
North American area code 408 is a telephone area code in California that covers most of Santa Clara County and includes Gilroy, Morgan Hill, Saratoga, Los Gatos, Monte Sereno, Milpitas, Sunnyvale, Santa Clara, Cupertino, and San Jose. It was created in a 1959 split from area code 415 in a flash-cut...
. It was not until the LeechModem software was leaked that it was discovered and counter-measures were built into BBS
Bulletin board system
A Bulletin Board System, or BBS, is a computer system running software that allows users to connect and log in to the system using a terminal program. Once logged in, a user can perform functions such as uploading and downloading software and data, reading news and bulletins, and exchanging...
software. Emulex/2 was the first BBS software to support Anti-LeechModem technology. This was because Sam Brown wrote Emulex/2 BBS
Bulletin board system
A Bulletin Board System, or BBS, is a computer system running software that allows users to connect and log in to the system using a terminal program. Once logged in, a user can perform functions such as uploading and downloading software and data, reading news and bulletins, and exchanging...
software as well. A common method was rounding the file size to the nearest kilobyte, causing the user to be unaware of the exact file size, rendering Leechmodem unusable.