r
R In a routing table, 'R' indicates a network that was learned dynamically using RIP.
R Programming language. First released in 1994 Website Wikipedia
R-Drive Image Drive imaging and backup program from R-Tools Technology Inc. Website Wikipedia
rabbit virus (fork bomb) Wikipedia
RACE Integrity Primitives Evaluation Message Digest (RIPEMD) (128, 160, 256, and 320-bit digests) Open standard family of cryptographic hash functions. Based on MD4 and is similar in performance to SHA-1. Not very common. Developed in Leuven, Belgium, by Hans Dobbertin, Antoon Bosselaers and Bart Preneel at the COSIC research group at the Katholieke Universiteit Leuven, and first published in 1996. Wikipedia
Radeon HD 7970 Released January 9, 2012. Wikipedia
Radeon R9 290X Released Oct 24, 2013. Wikipedia
Radeon R9 295X2 Released Apr 8, 2014. Wikipedia
Radeon R9 390X Released June 18, 2015. Wikipedia
Radeon R9 Fury Released July 14, 2015. Wikipedia
Radeon R9 Fury X Released June 24, 2015. Wikipeddia
Radeon R9 Nano Released August 27, 2015. Wikipedia
Radeon RX 460 GPU from AMD. Released August 8, 2016. Wikipedia
Radeon RX 470 GPU from AMD. Released August 4, 2016. Wikipedia
Radeon RX 480 GPU from AMD. Announced May 31, 2016. Released June 29, 2016. Website Anand Tech
Radia Perlman STP is based on an algorithm she invented. Born January 1, 1951. Wikipedia
Radio Corporation of America (RCA) Wikipedia
RADIUS client Gateway separating what is needed to be authenticated and those trying to authenticate. Wikipedia
RADIUS router configurations.
| Router(config)# aaa new-model |
| Router(config)# aaa authentication login default group radius none |
| Router(config)# radius-server host 192.168.1.3 auth-port 1812 access-port 1813 key WinRadius |
| Router(config)# username RadUser password RadUserPass |
RADIUS supplicant Person or device trying to be authenticated. Wikipedia
RAID 1 An exact copy (or mirror) of two or more drives. For optimal performance, the drives should be identical in model and capacity. Wikipedia
Rail fence cipher Words are spelled out as if they were a rail fence. Wikipedia Netacad
Raja Koduri Senior Vice President and Chief Architect, Radeon Technologies Group. AMD Executive Biography
Ralph Merkle Wikipedia
rand =rand(x,y) Adds random text to a word document.
Random Early Detection (RED) (aka: random early discard, random early drop) QoS tool that seeks to avoid congestion before it becomes an issue on the network. Wikipedia
Random-Access Memory (RAM) Volatile. In networking devices, RAM is used to store the running IOS, running configuration file, IP routing and ARP tables, and packet buffer. Wikipedia
ransomware Type of malware that requests payment to remove itself. Wikipedia
Rapid Application Development (RAD)
Rapid PVST+ The Cisco implementation of RSTP on a per-VLAN basis. Netacad
Rapid Spanning Tree Protocol (RSTP) IEEE 802.1w evolution of the original STP 802.1D standard. Wikipedia
Rapid STP (RSTP) (802.1w) Cisco
Raspberry Pi Website
ratio A comparison of two numbers.
| x to y | |
| x:y | |
| x/y | (x over y) |
raw_input() Wait for 'Enter' to be pressed before terminating in Python. StackOverflow
Razr Series of phones made by Motorola. First released in 2004. Wikipedia
RC Algorithms
| RC1 | Never published. |
| RC2 | Variable key-size block cipher that was designed as a 'drop-in' replacement for DES. |
| RC3 | |
| RC4 | World's most widely used stream cipher. |
| RC5 | |
| RC6 |
RCA Cable Red, White (audio) and, Yellow (video) analog cable. A type of coaxial cable. Wikipedia
rd Command that removes a directory.
Read Only Memory (ROM) Non-volatile. In networking devices, ROM is used to store bootstrap instructions, basic diagnostic software, limited IOS.
Read The F% Manual (RTFM) Acronym telling people to read the manual before asking why something doesn't work. Usually for simple/obvious mistakes that would have been avoided should the person have read the instructions. The F% can represent freaking, flipping, or other expletive to express emotion.
Read-Host PowerShell cmdlet that prompts a user for input. TechNet
Read-Only Domain Controller (RODC) Wikipedia
read-write (rw) might open up security holes
readonly Bash builtin to set a variable to read-only. Example: readonly VARIABLE. Same as declare -r.
Ready Player One Released March 30, 2018. IMDB Wikipedia
ReadyBoost Caching feature built into Windows Vista and later. Uses ReadyBoost-capable flash memory for better performance in random disk reads. Requires a drive between 256 MB and 32 GB, 1ms access time, 2.5 MBs 4 KB random read, and 1.75 MBs 512 KB random writes. Wikipedia
real number Any number that can be represented on a number line. Wikipedia Khan Academy
Real-Time Executive for Multiprocessor Systems (RTEMS) (formerly Real-Time Executive for Missile Systems, Real-Time Executive for Military Systems) Free and open-source Real-Time Operating System (RTOS) designed for embedded systems. Development began in the late 1980s with early versions available via ftp as early as 1993. Website Wikipedia
Real-Time Messaging Protocol (RTMP) (port 1935) Wikipedia
Real-time Transport Protocol (RTP or RTTP) Wikipedia
Realtek Audio-Video Background process (RAVBg64) RAVBg64.exe file.net
Received Signal Strength Indicator (RSSI) Measures the power of a wireless signal.
reconnaissance attack Gathers information about devices on the network and scans for access. This can include the use of packet sniffers and port scanners. Netacad Wikipedia
record A row of information in a database. An item. Wikipedia
RECOVER DOS command that recovers readable information from a bad or defective disk. Wikipedia
Recovery Point Objective (RPO) Maximum allowable amount of data (measured in time) an organization can afford to lose in an incident. I.E. the RPO for XYZ Company may be 4 hours. Wikipedia
Recursion Repeating items in a self-similar way. Wikipedia Wikipedia
Recursive acronym An acronym that refers to itself or another acronym, sometimes humorously.
recursive lookup When a router has to do multiple lookups in a routing table to forward a packet. A next-hop IP address used in a static route would cause a recursive lookup. These should be avoided when possible.
recursive static route A static route that uses an IP address as the next hop rather than an exit interface. Cisco
Red Hat Runs RHEL. Headquarters are in Raleigh, North Carolina. Founded in 1993. Website Wikipedia
Red Hat Enterprise Linux (RHEL) A Linux distribution used in servers and workstations because of its performance and support. Essentially the more stable release of Fedora. Website Wikipedia
Red Hat Linux (RHL) Wikipedia
redgedit Executable that can edit the registry in Windows. Microsoft Support
Redircmp.exe Redirects the default container for newly created computers to a specified, target organizational unit (OU) so that newly created computer objects are created in the specific target OU instead of in CN=Computers. Example: redircmp ou=newcomputerou,dc=domainname,dc=com TechNet
redistribute When two networks running different routing protocols need to communicate their route can be redistributed. Static routes (0.0.0.0 quad zero) can be used for connecting to ISPs. Cisco
Reduced Instruction Set Computing (RISC) Type of microprocessor that uses a simplified instruction set for better performance. Originated in the 1960's. Wikipedia
Redundant Array of Independent Disks (RAID) (formerly: Redundant Array of Inexpensive Disks) Configuration of multiple disks for redundancy (mirroring/parity) and sometimes performance (striping with RAID 0). Term "RAID" was invented by David Patterson, Garth A. Gibson, and Randy Katz at the University of California, Berkeley in 1987. Wikipedia
refactoring Process of restructuring existing computer code (changing the factoring) without changing its external behavior. A refactored file will work correctly but might also perform other malicious actions. Man in the Middle (MITM) might be the result of the refactor, but is not the threat itself. Wikipedia
reference model For networking, it clarifies the processes of networking and makes troubleshooting easier. Examples include TCP/IP and OSI.
referential integrity Ensures the primary and foreign keys match. Wikipedia
Reflexive ACL Allow packets to be filtered based on upper-layer session information. Csico
refresh rate (aka: "vertical refresh rate", "vertical scan rate" for cathode ray tubes) Number of times in a second the image on the screen can be completely redrawn by updating its buffer. Wikipedia
Regional Internet Registries (RIRs) RIRs are responsible for allocating IP addresses to ISPs.
register High-speed memory in a processor. Wikipedia
Registered Dual In-line Memory Module (RDIMM) (aka: buffered memory) Includes a specialized register chip that acts as a buffer between the DRAM modules and the memory controller. By buffering these signals, the electrical load placed on the controller is reduced because the memory controller communicates in series with the register, instead of in parallel with the memory chips. Wikipedia
Registered Jack (RJ) (ISO 8877) Standard connector used in data and telecommunication networks. Wikipedia
registry Similar to the Linux kernel. Wikipedia
regular expression Matches a pattern or sequence of characters. Wikipedia
rel HTML tag attribute. Specifies the relationship between the current document and the linked document. W3Schools
Relational Database Management System (RDBMS) Type of database management system (DBMS) based on the relational model of data. Most databases in widespread use today are based on this model. Wikipedia
Relative Distinguished Name (RDN) Wikipedia YouTube (Microsoft MCSA/MCSE Learning Channel)
Reliable Transport Protocol (RTP) Used in EIGRP. (TCP) Wikipedia
REM Command that records comments (remarks) in batch files or CONFIG.SYS.
Remington Rand Originally a typewriter manufacturer and later the manufacturer of UNIVAC. 1927 Wikipedia
Remote Access Trojan (RAT) Malicious software that is typically unknowingly installed which opens a back door for hackers. Notable examples include: Back Orifice, NetBus, iControl, PoisonIvy, Sub Seven, Beast Trojan, Bifrost, Blackshades, and DarkComet. Wikipedia
Remote Administrative Access Character mode Netacad
Remote Authentication Dial-In User Service (RADIUS) (UDP ports 1812, 1813,1645) Form of AAA used for authentication and network access. Does not handle authorization like TACACS+. Can use usernames and passwords from a variety of locations including on another server. Wikipedia
Remote Desktop Protocol (RDP) (TCP port 3389 UDP port 3389) Proprietary Microsoft protocol. Wikipedia
Remote Desktop Services (RDS) Wikipedia
remote host Located on a remote network and have different network addresses.
Remote Installation Services (RIS) TechNet Wikipedia
remote network Network that originate from another router and have different network addresses.
Remote Network Network/packet mode Microsoft TechNet Netacad
remote network entries
{ Router source | Destination network | [Administrative distance/Metric] | Next-hop | Route timestamp | Outgoing interface }
Remote Office / Branch Office (ROBO)
remote route Entry in a routing table that came from a remote network. Can be configured manually or learned dynamically.
Remote Server Administration Tools (RSAT)
remote-access VPN Connects individual users to a corporate network. Dynamic Wikipedia
ren Bash Command that renames a file or files in. Wikipedia
rename DOS command that renames a file or files. Wikipedia
Rename-Computer PowerShell command to change the hostname after restart.
Rename-Computer -NewName DC1 -Restart |
Rename-Item (aka: ren, rni) PowerShell cmdlet used to rename files and folders. TechNet Wikipedia
repetition control structure (aka: iteration control structure) Series of statements in a loop.
replace DOS command that replaces files.
replay attack Reusing intercepted non-secure credentials to gain access to a system or network.
REpresentational State Transfer (REST) Lightweight and scalable software architectural style that defines a set of constraints to be used for creating Web services. Web services that conform to the REST architectural style, called RESTful Web services, provide interoperability between computer systems on the Internet. RESTful Web services allow the requesting systems to access and manipulate textual representations of Web resources by using a uniform and predefined set of stateless operations. Other kinds of Web services, such as SOAP Web services, expose their own arbitrary sets of operations. Wikipedia
residual risk What risk remains after all mitigation and reduction strategies have been implemented.
Resilient File System (ReFS) Released with Windows Server 2012 August 1, 2012. Wikipedia
Resilio Sync (formerly BitTorrent Sync) Proprietary peer-to-peer file synchronization tool. Anounced January 24, 2013. Renamed to Resilio Sync on June 1, 2016 when it became managed under Resilio Inc. Website Wikipedia
reverse proxy Hides the server and can provide load balancing and caching for high activity pages. Wikipedia
Revo Uninstaller Website Wikipedia
RG-59 Type of coaxial cable, often used for low-power video and RF signal connections. The cable has a characteristic impedance of 75 ohms, and a capacitance of around 20pF/ft (60pF/m). Center conductor of 0.762mm. Sufficient for analog cable TV but not digital. Has a maximum distance of about 228 meters (750 feet). Wikipedia
RG-6/U Type of coaxial cable commonly used for cable TV or internet. Has a characteristic impedance of 75 ohms. Center conductor of 18 AWG (1.024 mm), can run up to 304 meters, or 1000 feet. Supports digital signals. Wikipedia
RG-8 Type of coaxial cable that was commonly used with 10Base5 (thicknet). Wikipedia
risk acceptance Risk response where the likelihood and the impact are less than the cost of mitigation. Level of risk the management authority chooses to accept with or without mitigations in place.
Rivest Cipher 4 (RC4) (aka: Alleged RC4 (ARC4), ARCFOUR) (1 round, 40-2048 bit key) Stream cipher popularized by its speed and simplicity. Part of some commonly used encryption protocols and standards, such as WEP, WPA, SSL, and TLS. Designed by Ron Rivest in 1987. Initially a trade secret, but in September 1994 a description of it was anonymously posted to the Cypherpunks mailing list. Prohibited for all versions of TLS by RFC 7465 in 2015, due to the RC4 attacks weakening or breaking RC4 used in SSL/TLS. Wikipedia
Routed Mode Firewall mode on the Cisco ASA. Functions as a Layer 3 device. Netacad
Request for Comments (RFC) Information about protocols and concepts that run the internet. Website
Research Triangle Park (RTP) One of the world's largest research parks. Located in North Carolina. Founded in 1959. Wikipedia
Reseaux IP Europeans (RIPE NCC) Website
resistance (R) Wikipedia
resistor Resists the flow of electricity. YouTube (Make:)
Resource Reservation Protocol (RSVP) QoS IntServ mechanism that reserves resources for an integrated services internet. Operates at OSI Layer 4 (transport). Defined in RFC 2205 September 1997. Wikipedia RFC 2205
Responsive design Same concept as RWD just generalized for other applications. Wikipedia
Responsive Web Design (RWD) Web pages that scale and resize depending on the size of the screen or browser window. Wikipedia
Restart-Computer PowerShell command that restarts Windows.
Restart-NetAdapter PowerShell command to restart a network adapter by disabling and then re-enabling the network adapter.
PS C:\> Restart-NetAdapter -Name "Ethernet 2"
Restart-Service PowerShell command to restart services.
Restart-Service -Name Spooler -Force | Restart the print spooler. |
Resultant Set of Policy (RSoP) Command rsop TechNet
Reverse Address Resolution Protocol (RARP) Ethernet type 0x8035.
Rich Site Summary (RSS) Wikipedia
Rich Skrenta Wrote the Elk Cloner virus. Wikipedia
Richard Stallman Wikipedia
Rijndael block cipher Developed by Joan Daemen and Vincent Rijmen.
RingCentral Cloud-based phone system. Founded in 1999 Website Wikipedia
Riser Cabling (Also known as Vertical cabling) Wikipedia
risk assessment (aka: risk identification) Evaluating probability and impact. Consists of a vulnerability assessment and a threat assessment. Threats + Vulnerability = Risk. Wikipedia
risk avoidance Risk response where the likelihood and the impact are so high that it is not dealt with. (i.e. not collecting PII because if it leaked, you could no longer do business.)
risk management framework
| categorize |
| select |
| implement |
| assess |
| authorize |
| monitor |
| (repeat) |
risk mitigation Risk response that reduces risk to a lower level.
risk response Process of how to handle risks. The four parts are:
| transference |
| mitigation |
| acceptance |
| avoidance |
risk transference Type of risk response where some of the risk, likelihood, and impact is offloaded to a third-party. (i.e. cloud hosting.)
Rivest-Shamir-Adleman (RSA) One of the most common asymmetric algorithms in public key cryptography. Typically used to generate digital signatures. Keys are usually 512 to 2048 bits. Acronym is the first letter from each surname of the developers; Ron Rivest, Adi Shamir, and Len Adleman. Published in 1977. Wikipedia
Rivest-Shamir-Adleman keys (RSA keys) Wikipedia Cisco Learning Network
Rivest-Shamir-Adleman signatures (RSA signatures) Authentication method used by IPsec Wikipedia
RJ-45 plug The standard connector used for LANs on Ethernet cable.
rm UNIX command to delete. Use del in DOS or OS/2. Wikipedia
rmdir DOS command that removes a directory.
Robert Kahn One of the fathers of the internet. Wikipedia
Robert Metacalf Founded 3COM. Wikipedia
Robert Noyce Co-founded Fairchild Semiconductor in 1957 and Intel Corporation in 1968. December 12, 1927 - June 3, 1990 Wikipedia
Robust File Copy for Windows (ROBOCOPY) Wikipedia Microsoft TechNet
Robust Security Network (RSN) Type of authentication. Windows Hardware Dev Center
Robust Security Network Association (RSNA) Type of authentication. Windows Hardware Dev Center
Rogue Access Point (Rogue AP) A wireless access point that has been installed on a network without explicit authorization from an administrator, whether added by a well-meaning employee or by a malicious attacker. Could be used by unauthorized individuals to bypass security controls such as firewalls. The potential of bypassing security controls is a good reason to perform a site survey of rogue access points. Wikipedia
Rogue One: A Star Wars Story Released December 16, 2016. IMDB
Rollover Cable (Console Cable) T658A to reversed T658A. Wikipedia
Ronald Wayne Co-founded Apple Computer with Steve Wozniak and Steve Jobs. Born May 17, 1934. Wikipedia
root bridge Bridge with the smallest (lowest) bridge ID. Switch in STP that determines which redundant paths to block. The root bridge switch can be set with a priority of 0. If multiple devices have a priority of 0, it will chose the one with the lowest MAC address. Wikipedia
root hints Resolve queres for zones that don't exist on the local DNS server. Only use if forwaders are not configured or fail to respond YouTube (Microsoft MCSA/MCSE Learning Channel)
root mean square (RMS) (aka: effective value)
- RMS = peak × 0.707
- peak = RMS × 1.414
root port Switch ports closest to the root bridge
Roslyn .NET compiler Wikipedia
Round Robin (RR) Network scheduling algorithm. Wikipedia
route -n Linux command to show the routing table. (Use route print for Windows.)
route poisoning Wikipedia
route print Shows the routing table in Windows. (Use route -n for Linux.)
route resolvability The process used by the routing table to determine the exit interface used to forward a packet.
route source How a route was learned in a routing table. Usually represented by the first letter of the routing protocol or the kind of connection. (i.e. R for a RIP route, C for a directly connected route, S for a static route...)
route summarization (route aggregation) advertising a contiguous set of addresses as a single address with a less-specific, shorter subnet mask.
route timestamp When a route was last heard in a routing table.
router routes packets across different networks and to other devices on the current network. Wikipedia
Router Advertisement (RA) Message sent by IPv6 routers to advertise their presence. Provides addressing information to hosts using SLAAC.
Router Discovery Protocol (RDP)
router eigrp IOS command used to enable EIGRP (no router eigrp turns it off)
router ID Both IPv4 and IPv6 use the same 32-bit router ID in EIGRP. Can be configured with the
router on a stick Allows hosts logically separated by a VLAN to communicate. Wikipedia
router rip command used on routers to enable RIP
Router Solicitation (RS) When configured with SLAAC, a host will send an RS message to the router.
routing Choosing the best path through a network. Wikipedia
Routing Information Base (RIB) Also known as the routing table. Wikipedia
Routing Information Protocol (RIP) (Administrative Distance: 120, UDP port 520) Distance-vector routing protocol that uses hop count as a routing metric. Has a maximum hop count of 15. Implements the split horizon, route poisoning and holddown mechanisms to prevent incorrect routing information from being propagated. Uses multicast address 255.255.255.255. Wikipedia
Routing Information Protocol (RIPng) An extension of RIPv2 that supports IPv6. Wikipedia
Routing Information Protocol Version 2 (RIPv2) Uses UDP through port 520. Broadcast 224.0.0.9 Wikipedia
routing loop Where duplicate frames are sent across the network to the same router and get stuck in a loop. Wikipedia
routing protocol How routers communicate with each other. A set of processes, algorithms, and messages used to exchange routing information and populate the routing table with the best path. Wikipedia
routing table Each router or computer has a unique routing table of where to send packets. Volatile. Table in the OSPF forwarding database. [Route source | Destination network | Outgoing interface] Can be shown using route print on Windows, route -n on Linux, and show ip route on Cisco IOS. Wikipedia Microsoft TechNet
RS-232 (serial connection) Now replaced by the newer USB standard on PCs. Some WANs may still use a serial connection though. Wikipedia Wikipedia
RS-423 Wikipedia
RSA Conference 2018 April 16 - April 20. Website
RSA Congerence USA 2019 March 4-8, 2019 at Moscone Center in San Francisco. Website
RSA-encrypted nonce Wikipedia Cisco Press
rsync Backup utility for Linux-based computers. Wikipedia
RTLinux Hard realtime RTOS microkernel that runs the entire Linux operating system as a fully preemptive process. Discontinued August 2011. Website Wikipedia
RTV-G-4 Bumper United States rocket. Bumper 8 was the first successful rocket to launch from Cape Canaveral on July 24, 1950. Wikipedia
ruby programing language. Wikipedia Code School - Try Ruby
ruby on rails Open-source web framework. Wikipedia Website
running configuration file Current configuration in Cisco IOS
Ryzen (codename: Summit Ridge) CPU family from AMD. Announced February 22, 2017. First relesed March 2, 2017. Website Wikipedia