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{{Short description|Access control list software}}
{{Infobox_Software
__NOTOC__
⚫ |name = TCP Wrapper
⚫ {{Infobox software
|logo =
⚫ | name = TCP Wrapper
⚫ |caption =
|screenshot = | logo =
⚫ | caption =
|developer = Wietse Venema
| screenshot =
⚫ |latest_release_version = v0.7.6
|operating_system = ] | developer = ]
⚫ | latest_release_version = 7.6 (April 08, 1997)
⚫ |genre = Security
|license = ] | operating_system = ]
⚫ | genre = Security
⚫ |website =
| license = ]
⚫ | website =
}} }}
⚫ '''TCP Wrappers''' (also known as '''tcp_wrappers''') is a host-based networking ] system, used to ] network access to ] servers on (]) ]s such as ] or ]. It allows host or ] ]es, ] and/or ] query replies, to be used as tokens on which to filter for ] purposes.


The original code was written by ] in 1990 to monitor a cracker's activities on the ] workstations at the Department of Math and Computer Science at the ].<ref></ref> He maintained it until 1995, and on June 1, 2001, released it under its own ].
⚫ '''TCP Wrapper''' is a host-based ] ] system, used to ] network access to ] ] ] run on (]) ] such as ] or ]. It allows host or ] ], ] and/or ] query replies, to be used as tokens on which to filter for ] purposes. The name ''Wrapper'' is a reference to the ] (of the 'tcpd' program included).


⚫ The ]ball includes a ] named '''libwrap''' that implements the actual functionality. Initially, only services that were spawned for each connection from a ] (such as ]) got ''wrapped'', utilizing the '''tcpd''' program. However most common network service ] today can be ] against libwrap directly. This is used by daemons that operate without being spawned from a super-server, or when a single process handles multiple connections. Otherwise, only the first connection attempt would get checked against its ACLs.
The original code was written by ] at the ], ], between 1990 and 1995. As of June 1, 2001 the program is released under its own ].


⚫ When compared to host access control directives often found in daemons' configuration files, TCP Wrappers have the benefit of ] ACL reconfiguration (i.e., services don't have to be reloaded or restarted) and a generic approach to network administration.
⚫ The ] includes a ] named ''']''' that implements the actual functionality. Initially only services that start from a super-server (such as ]) got ''wrapped'', utilizing the 'tcpd' program. However most common network service ] today can be ] against libwrap directly, and thus honor TCP Wrapper ACLs even when in stand-alone operating mode.


This makes it easy to use for anti-] scripts, such as ] or ], to add and expire client-blocking rules, when excessive connections and/or many failed login attempts are encountered.
⚫ Over host access control directives often found in daemons' configuration files, TCP Wrappers have the benefit of ] ACL reconfiguration (i.e. services don't have to be reloaded or restarted) and a generic approach to network administration.


While originally written to protect ] and ] accepting services, examples of usage to filter on certain ] packets (such as 'pingd' &ndash; the ] ping request responder) exist too. While originally written to protect ] and ] accepting services, examples of usage to filter on certain ] packets exist too, such as 'pingd' &ndash; the ] ] request responder.<ref> by route|daemon9 - Phrack Magazine Volume 8, Issue 52 January 26, 1998, article 07</ref>


==1999 Trojan==
Services that grab the ] after being started by a super-server (for performance reasons on consecutive connects &ndash; usually ] ] such as: Peter Anvin's tftpd and Peter Eriksson's identd), '''have''' to be linked against libwrap rather than wrapped (by tcpd, xinetd, or similar) as otherwise only the first connection attempt gets checked against its ACLs.
In January 1999, the distribution package at ] (the primary distribution site until that day) was replaced by a modified version. The replacement contained a trojaned version of the software that would allow the intruder access to any server that it was installed on. The author spotted this within hours, upon which he relocated the primary distribution to his personal site.<ref>{{cite web |title=CERT Advisory CA-1999-01 Trojan horse version of TCP Wrappers |url=https://resources.sei.cmu.edu/asset_files/WhitePaper/1999_019_001_496184.pdf#page=5 |website=Carnegie Mellon University Software Engineering Institute |archive-url=https://web.archive.org/web/20001017170613/http://www.cert.org/advisories/CA-1999-01.html |archive-date=2000-10-17 |access-date=15 September 2019 |url-status=live}}</ref><ref>{{cite web |title=CERT Advisory CA-1999-02 Trojan Horses |url=https://resources.sei.cmu.edu/asset_files/WhitePaper/1999_019_001_496184.pdf#page=14 |website=Carnegie Mellon University Software Engineering Institute |archive-url=https://web.archive.org/web/20001017172300/http://www.cert.org/advisories/CA-1999-02.html |archive-date=2000-10-17 |access-date=15 September 2019 |url-status=live}}</ref><ref>, on ], Jan 21, 1999</ref><ref>, on ], Jan 21, 1999</ref>

The project is usually referred to as TCP Wrappers and is named tcp-wrappers in the ] ] package repository. In Gentoo Linux TCP Wrappers is enabled with the 'tcpd' use-flag.


==See also== ==See also==
{{Portal|Free and open-source software}}


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== References == ==References==
{{reflist}}
*]: July 15 ]
*]: Linuxjournal article ]-08-01


==External links== ==External links==
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* - vBulletin Optmizing Tips
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Latest revision as of 02:21, 20 November 2023

Access control list software
TCP Wrapper
Developer(s)Wietse Venema
Stable release7.6 (April 08, 1997)
Operating systemUnix-like
TypeSecurity
LicenseBSD license
Websiteporcupine.org

TCP Wrappers (also known as tcp_wrappers) is a host-based networking ACL system, used to filter network access to Internet Protocol servers on (Unix-like) operating systems such as Linux or BSD. It allows host or subnetwork IP addresses, names and/or ident query replies, to be used as tokens on which to filter for access control purposes.

The original code was written by Wietse Venema in 1990 to monitor a cracker's activities on the Unix workstations at the Department of Math and Computer Science at the Eindhoven University of Technology. He maintained it until 1995, and on June 1, 2001, released it under its own BSD-style license.

The tarball includes a library named libwrap that implements the actual functionality. Initially, only services that were spawned for each connection from a super-server (such as inetd) got wrapped, utilizing the tcpd program. However most common network service daemons today can be linked against libwrap directly. This is used by daemons that operate without being spawned from a super-server, or when a single process handles multiple connections. Otherwise, only the first connection attempt would get checked against its ACLs.

When compared to host access control directives often found in daemons' configuration files, TCP Wrappers have the benefit of runtime ACL reconfiguration (i.e., services don't have to be reloaded or restarted) and a generic approach to network administration.

This makes it easy to use for anti-worm scripts, such as DenyHosts or Fail2ban, to add and expire client-blocking rules, when excessive connections and/or many failed login attempts are encountered.

While originally written to protect TCP and UDP accepting services, examples of usage to filter on certain ICMP packets exist too, such as 'pingd' – the userspace ping request responder.

1999 Trojan

In January 1999, the distribution package at Eindhoven University of Technology (the primary distribution site until that day) was replaced by a modified version. The replacement contained a trojaned version of the software that would allow the intruder access to any server that it was installed on. The author spotted this within hours, upon which he relocated the primary distribution to his personal site.

See also

References

  1. TCP WRAPPER - Network monitoring, access control, and booby traps. by Wietse Venema (USENIX UNIX Security Symposium III, 1992)
  2. GNU/Linux Ping Daemon by route|daemon9 - Phrack Magazine Volume 8, Issue 52 January 26, 1998, article 07
  3. "CERT Advisory CA-1999-01 Trojan horse version of TCP Wrappers" (PDF). Carnegie Mellon University Software Engineering Institute. Archived from the original on 2000-10-17. Retrieved 15 September 2019.
  4. "CERT Advisory CA-1999-02 Trojan Horses" (PDF). Carnegie Mellon University Software Engineering Institute. Archived from the original on 2000-10-17. Retrieved 15 September 2019.
  5. backdoored tcp wrapper source code, by Wietse Venema, on Bugtraq, Jan 21, 1999
  6. Announcement: Wietse's FTP site has moved, by Wietse Venema, on Bugtraq, Jan 21, 1999

External links

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