Dialup Users List
Encyclopedia
A Dynamic Users List is a type of DNSBL
which contains the IP addresses an ISP
assigns to its customer on a temporary basis, often using DHCP
or similar protocols. Dynamically assigned IP addresses are contrasted with static IP addresses which do not change once they have been allocated by the service provider.
DULs serve several purposes. Their primary function is to assist an ISP in enforcement of its Acceptable Use Policy
, most of which prohibit customers from setting up an email server. Customers are expected to use the email facilities of the service provider. This use of a DUL is especially helpful in curtailing abuse when a customer's computer has been converted into a zombie computer
and is distributing email without the knowledge of the computer's owner. A second major use involves receivers who do not wish to accept email from computers with dynamically assigned email addresses. They use DULs to enforce this policy. Receivers adopt such policies because computers at dynamically assigned IP addresses so often are a source of spam.
The first DUL was created by Gordon Fecyk in 1998. It quickly became quite popular because it addressed a specific tactic popular with spammers at the time. The DUL subsequently was absorbed by Mail Abuse Prevention System
(MAPS) in 1999. When MAPS was no longer a free service, other DNSBLs such as Dynablock
, Not Just Another Bogus List
(NJABL), and Spam and Open Relay Blocking System
(SORBS) began providing lists of dynamically assigned IP addresses.
DNSBL
A DNSBL is a list of IP addresses published through the Internet Domain Name Service either as a zone file that can be used by DNS server software, or as a live DNS zone that can be queried in real-time...
which contains the IP addresses an ISP
Internet service provider
An Internet service provider is a company that provides access to the Internet. Access ISPs directly connect customers to the Internet using copper wires, wireless or fiber-optic connections. Hosting ISPs lease server space for smaller businesses and host other people servers...
assigns to its customer on a temporary basis, often using DHCP
Dynamic Host Configuration Protocol
The Dynamic Host Configuration Protocol is a network configuration protocol for hosts on Internet Protocol networks. Computers that are connected to IP networks must be configured before they can communicate with other hosts. The most essential information needed is an IP address, and a default...
or similar protocols. Dynamically assigned IP addresses are contrasted with static IP addresses which do not change once they have been allocated by the service provider.
DULs serve several purposes. Their primary function is to assist an ISP in enforcement of its Acceptable Use Policy
Acceptable use policy
An acceptable use policy is a set of rules applied by the owner/manager of a network, website or large computer system that restrict the ways in which the network site or system may be used...
, most of which prohibit customers from setting up an email server. Customers are expected to use the email facilities of the service provider. This use of a DUL is especially helpful in curtailing abuse when a customer's computer has been converted into a zombie computer
Zombie computer
In computer science, a zombie is a computer connected to the Internet that has been compromised by a cracker, computer virus or trojan horse and can be used to perform malicious tasks of one sort or another under remote direction. Botnets of zombie computers are often used to spread e-mail spam...
and is distributing email without the knowledge of the computer's owner. A second major use involves receivers who do not wish to accept email from computers with dynamically assigned email addresses. They use DULs to enforce this policy. Receivers adopt such policies because computers at dynamically assigned IP addresses so often are a source of spam.
The first DUL was created by Gordon Fecyk in 1998. It quickly became quite popular because it addressed a specific tactic popular with spammers at the time. The DUL subsequently was absorbed by Mail Abuse Prevention System
Mail Abuse Prevention System
The Mail Abuse Prevention System ' is an organisation that provides anti-spam support by maintaining a DNSBL. They provide five black lists, categorising why an address or an IP block is listed:...
(MAPS) in 1999. When MAPS was no longer a free service, other DNSBLs such as Dynablock
Dynablock
Dynablock is a name which was used by Easynet from 2001 to 2003 for their Dialup Users List DNSBL of Internet addresses that appeared to be assigned dynamically, i.e. to dialup and residential broadband users....
, Not Just Another Bogus List
Not Just Another Bogus List
Not Just Another Bogus List, or NJABL, is a DNS blacklist.NJABL maintains a list of known and potential spam sources for the purpose of being able to tag or refuse e-mail and thereby block spam from certain sources...
(NJABL), and Spam and Open Relay Blocking System
Spam and Open Relay Blocking System
SORBS is a list of e-mail servers suspected of sending or relaying spam . It has been augmented with complementary lists that include various other classes of hosts, allowing for customized email rejection by its users.-History:The SORBS DNSbl project was created November 2002...
(SORBS) began providing lists of dynamically assigned IP addresses.