Looking Glass servers (LG servers) are

server Server may refer to: Computing *Server (computing), a computer program or a device that provides functionality for other programs or devices, called clients Role * Waiting staff, those who work at a restaurant or a bar attending customers and su ...

s on the

Internet The Internet (or internet) is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a ''internetworking, network of networks'' that consists ...

running one of a variety of publicly available Looking Glass software implementations. They are commonly deployed by

autonomous system Autonomous system may refer to: * Autonomous system (Internet), a collection of IP networks and routers under the control of one entity * Autonomous system (mathematics), a system of ordinary differential equations which does not depend on the inde ...

s (AS) to offer access to their routing infrastructure in order to facilitate

debugging In computer programming and software development, debugging is the process of finding and resolving ''bugs'' (defects or problems that prevent correct operation) within computer programs, software, or systems. Debugging tactics can involve in ...

network issues. A Looking Glass server is accessed remotely for the purpose of viewing

routing Routing is the process of selecting a path for traffic in a network or between or across multiple networks. Broadly, routing is performed in many types of networks, including circuit-switched networks, such as the public switched telephone netw ...

information. Essentially, the

acts as a limited, read-only portal to routers of whatever organization is running the LG server. Typically, Looking Glass servers are run by

s like

Internet service provider An Internet service provider (ISP) is an organization that provides services for accessing, using, or participating in the Internet. ISPs can be organized in various forms, such as commercial, community-owned, non-profit, or otherwise privatel ...

s (ISPs),

Network Service Provider Network Service Provider (NSP) is one of the roles defined in the National Information Infrastructure (NII) plan, which governed the transition of the Internet from US federal control to private-sector governance, with an accompanying shift from th ...

s (NSPs), and

Internet exchange point Internet exchange points (IXes or IXPs) are common grounds of IP networking, allowing participant Internet service providers (ISPs) to exchange data destined for their respective networks. IXPs are generally located at places with preexisting ...

s (IXPs).

Implementation

Looking glasses are web scripts directly connected to routers' admin interfaces such as

telnet Telnet is an application protocol used on the Internet or local area network to provide a bidirectional interactive text-oriented communication facility using a virtual terminal connection. User data is interspersed in-band with Telnet cont ...

and SSH. These scripts are designed to relay textual commands from the web to the router and print back the response. The are often implemented in

Perl Perl is a family of two High-level programming language, high-level, General-purpose programming language, general-purpose, Interpreter (computing), interpreted, dynamic programming languages. "Perl" refers to Perl 5, but from 2000 to 2019 it ...

PHP PHP is a General-purpose programming language, general-purpose scripting language geared toward web development. It was originally created by Danish-Canadian programmer Rasmus Lerdorf in 1993 and released in 1995. The PHP reference implementati ...

, and Python, and are publicly available on

GitHub GitHub, Inc. () is an Internet hosting service for software development and version control using Git. It provides the distributed version control of Git plus access control, bug tracking, software feature requests, task management, co ...

Security concerns

A 2014 paper demonstrated the potential security concerns of Looking Glass servers, noting that even an "attacker with very limited resources can exploit such flaws in operators' networks and gain access to core Internet infrastructure", resulting in anything from traffic disruption to global

Border Gateway Protocol Border Gateway Protocol (BGP) is a standardized exterior gateway protocol designed to exchange routing and reachability information among autonomous systems (AS) on the Internet. BGP is classified as a path-vector routing protocol, and it mak ...

(BGP) route injection. This is due in part because looking glass servers are "an often overlooked critical part of an operator infrastructure" because it sits at the intersection of the public internet and "restricted admin consoles". As of 2014, most Looking Glass software were small and old, having last been updated in the early 2000's.

References

{{Reflist

External links

Source code for the *original* Multi-Router Looking Glass (MRLG) by John Fraizer
@ OP-SEC.US * Packet Clearing Housebr>Looking Glass servers
around the world.
Looking Glass server source code

Clickable map of known Reverse Lookup and Looking Glass servers in the world

Looking Glass Wiki
- List of hundreds of Looking Glass servers, sorted by

Autonomous System Number An autonomous system (AS) is a collection of connected Internet Protocol (IP) routing prefixes under the control of one or more network operators on behalf of a single administrative entity or domain, that presents a common and clearly defined rou ...

.
IPv4 and IPv6 BGP Looking Glasses
at BGP4.as
BGP Looking Glass links
collection at LookinGlass.org
CSpace Hostings Looking Glass
a Network Service Providers looking glass example. * RFC 8522: Looking Glass Command Set Servers (computing)

Implementation

Security concerns

See also

References

External links