349 results

S Identifies a static route created to reach a specific network in a routing table.            

S-Video (aka: separate video, Y/C) Signaling standard for standard definition video, typically 480i or 576i. It transmits video signals over a cable by dividing the video information into two separate signals: one for color (chrominance), and the other for brightness (luminance). Better image quality than composite video, but has lower color resolution than component video. Uses a 4, 7, or 9 pin Mini-DIN connector. Designed in 1987.  Wikipedia         

SA database (SADB) Maintains security associations.   Netacad         

Safari Web browser from Apple. irst released January 7, 2003. Version 1.0 released June 23, 2003.  Website  Wikipedia       

Samba A file type of file server.   Samba documentation  Ubuntu documentation       

Samsung  Founded March 1, 1938.  Wikipedia         

Samsung Galaxy Note 8 Smartphone from Samsung.

  • 160 mm (6.3 in)
  • QHD+ Super AMOLED
  • 2960 x 1440 (1440p)
  • 521 ppi
  • Global: Exynos 8895
  • North America: Snapdragon 835
  • Global: 64 GB, 128 GB, or 256 GB
  • North America: 64 GB
  • microSDXC, expandable up to 256 GB
  • Rear camera: Dual 12 MP
    • Wide-angle f/1.7
    • Telephoto f/2.4
  • Front camera: 8 MP, f/1.7B
 Announced August 23, 2017. Released September 15, 2017.  Website  Wikipedia       

Samsung Galaxy S8 Smartphone from Samsung Announced March 29, 2017. Released April 21, 2017.  Website  Wikipedia       

Samsung Galaxy S9 Smartphone from Samsung. Announced February 25, 2018 at Mobile World Congress (MWC) 2018.  Website  Wikipedia       

sandbox Security mechanism for separating running programs, usually in an effort to mitigate system failures or software vulnerabilities from spreading.   Wikipedia         

Sandy Bridge Microarchitecture codename from Intel. First released January 5, 2011.  Wikipedia         

SANS Institute    Wikipedia  Website       

sans-serif    Wikipedia         

SC.exe    TechNet         

scalar Indicates magnitude only.   Wikipedia         

schema Defines attributes for all Active Directory (AD) objects.   Wikipedia         

schematics Simplified representation of an electronic circuit.   YouTube (Make:)         

scratch space (aka: scratch drive) Logical or physical space dedicated to temporarily work with data. Commonly used in programs that need more memory than the available RAM such as Adobe Photoshop.   Wikipedia         

scrum Iterative and incremental agile software development framework for managing product development.   Wikipedia         

scutil Command used on a Mac to set the hostname.   OS X Man Pages         

scytale Possibly one of the first transposition cipher tools.   Wikipedia         

SeaTools Hard drive analysis tool from Seagate. First released January 30, 2007.  Website  Wikipedia       

Second Level Address Translation (SLAT) (aka: nested paging) Hardware-assisted virtualization technology.   Wikipedia         

Secure Copy (SCP) (TCP port 22) Secure way to copy files between two computers. Example: scp SourceFile user@host:directory/TargetFile   Wikipedia  John Veldboom       

Secure Device Manager (SDM) Management software for Cisco routers            

Secure Digital (SD)             

Secure Digital eXtended Capacity (SDXC)  Announced January 2009.  Wikipedia         

Secure Digital High Capacity (SDHC)  Announced January 2006.  Wikipedia         

Secure European System for Applications in a Multivendor Environment (SESAME) European-developed authentication protocol that can provide for single sign-on capability. It is not widely used and does not use tickets for authentication.            

Secure Hash Algorithm (SHA)

SHA-1 (Legacy) Uses a 160-bit secret key.
SHA-2 SHA-224, SHA-256, SHA-384, SHA-512
   Wikipedia (SHA-1)  Wikipedia (SHA-2)  Wikipedia (SHA-3)  Cisco  Netacad 

Secure Hash Algorithm 1 (SHA-1) Cryptographic hash function which produces a 160-bit hash value known as a message digest. part of several widely used security applications and protocols, including TLS and SSL, PGP, SSH, S/MIME, and IPsec. Can provide data integrity in a VPN. Designed by the United States National Security Agency (NSA). not been considered secure since 2005.  Wikipedia         

Secure Hash Standard (SHS)    Wikipedia         

Secure Shell (SSH) A more secure form of telnet that uses port 22 instead of port 23 as in the case of telnet.   Cisco  Pluralsight blog       

Secure Shell (SSH) Configuration Can be configured on a Cisco device with a;

hostname carter
aaa new-model
username cisco password 0 cisco
ip domain-name rtp.cisco.com
crypto key generate rsa
ip ssh time-out 60
ip ssh authentication-retries 2
line vty 0 4
transport input SSH


Secure Sockets Layer (SSL) Can be used to established remote-access VPN connections. Initially published as SSL 2.0 February 1995.  Wikipedia  Instant SSL by Comodo       

Secure Sockets Layer Certificate (SSL Certificate)    YouTube         

secure software development model

Requirements Requirements for different security functions are determined.
Testing Software is measured or tested against security, functionality, and performance requirements. (secure code review, application fuzzing, vulnerability assessments, and penetration testing.)
Design Security functionality is designed into the application.
Implementation Security requirements are validated as implemented in the application.

Secure/Multipurpose Internet Mail Extensions (S/MIME)    Wikipedia         

Security Alert Error: "The name on the security certificate is invalid or does not match the name of the site." Issued to: *.btrll.com. Description: Ads displayed in Yahoo Mail have an invalid SSL certificate. Solution: Block the advertisements with an ad blocker.   Yahoo Help Community         

security and functionality relationship As security increases, functionality decreases. As resources decrease, both functionality and security decrease.            

Security and Maintenance (Formerly Action Center and Windows Security Center)   Microsoft Support  Wikipedia       

Security Assertion Markup Language (SAML) Used for web application login.   Wikipedia         

Security Association (SA) Part of the IPsec suite used to negotiate the cryptographic parameters between two devices in an ISAKMP session. Performed after AH or ESP has been selected. Maintained by a SADB.   Wikipedia  Netacad       

security authentication failure rate             

security controls Risk likelihood and impact should directly determine how much is budgeted for security controls. Can be classified by when the occur or according to their nature.

Security Functions:

Security Controls:


Security Device Manager (SDM)    Cisco         

Security Event Manager (SEM) Real-time monitoring of logs and events generated by devices or software on the network.   Wikipedia         

Security Identifier (SID) Unique value of variable length used to identify a trustee.   MSDN  Wikipedia       

Security Information and Event Management (SIEM) Combines Security Information Management (SIM) and Security Event Management (SEM) software products and services. Analyzes security alerts from networking equipment and software in real-time. Can aggregate and correlate data, allowing you to organize it into valuable information. Splunk is an example of SIEM. Coined by Mark Nicolett and Amrit Williams of Gartner in 2005.  Wikipedia         

Security Information Management (SIM) Central location for long-term storage analysis of log data.   Wikipedia         

security operations (SecOps)             

Security Operations Center (SOC)    Wikipedia         

Security Services Module (SSM)             

Sega Japanese video game company. Founded in 1940 as Service Games. Renamed to Sega June 3, 1960.  Wikipedia         


Segmentation Dividing a data stream into small pieces.            

SELECT SQL statement that returns a set of records from one or more tables. Main data retrieval command in SQL.   Wikipedia         

self induction When a coil induces voltage into itself.            

Self-Monitoring, Analysis and Reporting Technology (S.M.A.R.T) (often written as SMART) Keeps track of the health of a hard disk drive (HDD) or solid-state drive (SSD).   Wikipedia         

self-similarity (fractals)   Wikipedia         

Semiconductor    Wikipedia         

sequence control structure Series of statements that follow one another.            

Sequence Number             

Sequoia Supercomputer from IBM Installed at the Lawrence Livermore National Laboratory (LLNL) in 2011.  Wikipedia         

Sergey Brin Co-founded Google with Larry Page. Born August 21, 1973.  Website  Wikipedia       

serial Sends information in a single stream, one at a time. (bidirectional)            

Serial Advanced Technology Attachment (SATA)  Released in 2003.  Wikipedia         

Serial Attached SCSI (SAS) Point-to-point serial protocol used for storage devices.   Wikipedia         

Serial Line Internet Protocol (SLIP) standard protocol for point-to-point serial connections using TCP/IP   Netacad         

serial port             

serial WAN interfaces             


server A host used to serve information to other clients.            

Server Core Stripped-down version of Windows server managed from the command line. First released in Windows Server 2008.    Wikipedia       

Server Message Block (SMB) Application-layer protocol mainly used for providing shared access to files, printers, serial ports, and miscellaneous communications between nodes on a network. Primarily used in Windows networks.   Wikipedia         

Service Level Agreement (SLA) Agreement between two parties that specifies the level of service and support. Can outline QoS parameters for packets going through a provider.   Wikipedia         

service provider             

service sequence-numbers Service on networking devices that puts sequence numbers in syslog messages.            

Service Set    Wikipedia         

Service Set Identifier (SSID) (aka: BSSID) Associated with the MAC address on a wireless Access Point (AP). Identify logical networks (including extended service sets) and serve as the "network name".   Wikipedia         

services.msc Services in Windows.            

Serving Area Interface (SAI) Outdoor enclosure or metal box that allows access to telecommunications wiring.   Wikipedia         


session cookies Typically created for a single web browsing session and are generally not carries across web sessions. Persistent cookies are saved and used between sessions.   Wikipedia         

session hijacking (aka: cookie hijacking) Intercepting and taking over an in-progress communications session between two hosts.   Wikipedia         

Session Initiation Protocol (SIP) (port 5060)   Wikipedia  YouTube       

Session Layer (OSI Layer 5) Establishes and controls data communication between applications operating on two computers.   Wikipedia         

session table             

SET Displays, sets, or removes Windows environment variables.            

Set-ADAccountExpiration PowerShell cmdlet used to set the expiration time of a user, computer, or service account.   TechNet         

Set-ADUser PowerShell cmdlet used to modify an Active Directory user.   TechNet         

Set-Date PowerShell command that changes the date or time.   TechNet         

Set-Item WSMan:\localhost\Client\TrustedHosts -Value hostname -Force             

Set-ItemProperty PowerShell cmdlet. Can be used to change registry values. Introduced in PowerShell 3.0.  TechNet         

Set-NetConnectionProfile PowerShell cmdlet that changes the network category of a connection profile. Introduced in Windows Server 2012 and Windows 8.  TechNet         

Set-NetIPAddress PowerShell cmdlet used to change an IP address.   TechNet         

Set-SmbServerConfiguration PowerShell cmdlet used to disable SMB1. Set-SmbServerConfiguration -EnableSMB1Protocol $false   Microsoft Support         

Set-VHD PowerShell cmdlet used to modify a virtual hard disk.   TechNet         

Set-VM PowerShell cmdlet used to configure a virtual machine.   Website         

SETLOCAL Begins localization of environment changes in a batch file.            

Seymour Cray The father of supercomputing. September 28, 1925 - October 5, 1996  Wikipedia         

shared library File that is shared by an executable.   Wikipedia         

shared secret password or passphrase.   Wikipedia         

Shebang #! Starts a script in UNIX.   Wikipedia         

Shell Provides a user interface for accessing an operating system's services.   Wikipedia         

Shell Script Program that is run by the UNIX shell.   Wikipedia  Ubuntu documentation       

Shielded Twisted Pair (STP) A type of twisted pair cabling with a layer of braided foil shielding surrounding the wires to reduce electrical interference.   Wikipedia         

shift Shifts the position of replaceable parameters in batch files.   Microsoft documentation         

Shift + F5 Refresh without looking at local cache.   Wikipedia         

Shift key Key that modifies or "shifts" the keys on a keyboard to another function such as capital letters.   Wikipedia         

Short Message Service (SMS)    Wikipedia         

short text data type that can contain any characters with a maximum of 255.            

Shortest Path First (SPF)             

shoulder surfing Looking over someone's shoulder as they type in a password.            

show commands Commands in Cisco IOS that show.., stuff.

show arp IOS command to show the ARP table.
show interfaces
show ip eigrp neighbors
show ip eigrp topology
show ip interface brief Command to show a list of interfaces and any IPv4 addresses that might be assigned to them. Use show ipv6 interface brief to show IPv6 interfaces
show ip ospf process ID, router, id, OSPF SPF, OSPF, area information
show ip ospf database Shows LSDB area, link id
show ip ospf interface Shows details about all OSPF enabled interfaces the router ID.
show ip ospf interface interface id Details about a particular OSPF enabled interface
show ip ospf interface brief Concise OSPF-related information of OSPF-enabled interfaces, OSPF process id, area, cost, brief
show ip ospf neighbor OSPF adjacencies and the router IDs of those routers
show ip protocols Shows the protocols on a router. OSPF process ID, router ID, advertised networks, neighbors the router is receiving updates from, and the administrative distance.
show ip route Command used to display IPv4 routing table of a router
show ip route eigrp
show ip route ospf Shows only OSPF routes in the routing table
show ipv6 route Shows the IPv6 routing table on a network device
show running configuration Shows the running configuration file
show flash Contents of the flash
show boot Location of the configuration file
show version Current IOS version

show ip bgp ipv4 unicast             

show license             

show spanning-tree             

shutdown Command that turns a network devices interface off.            

Shutdown /o Go to the advanced boot options menu and restart the computer. Must be used with /r option. Introduced in Windows 8.  MSDN  The Windows Club       

SICM    Website  Wikipedia       

sideloading Installing applications from a source other than the operating system's default app store.   Wikipedia         

Sierra (macOS 10.12) Released September 20, 2016.  Website  Wikipedia       

SIGGRAPH 2017  July 30, 2017 - August 3, 2017 at the Los Angeles Convention Center.  Event Website  Main Website  Wikipedia     

signal-to-noise ratio (SNR)    Wikipedia         

Silicon    Wikipedia         

simple attribute Attribute that cannot be subdivided.            

Simple Mail Transfer Protocol (SMTP) (TCP port 25) Transfers mail messages and attachments.   Wikipedia         

Simple Mail Transfer Protocol Secure (SMTPS) port 465   Wikipedia         

Simple Network Management Protocol (SNMP) Service uses port 161, trap uses port 162. Uses SNMP managers, agents, and MIBs. Consumes more bandwidth than Syslog. First defined in RFC 1067 August 1988.  Wikipedia  RFC 1067  Cisco (Configuring SNMP)  Netacad  CCIE or Null! 

Simple Network Management Protocol version 1 (SNMPv1) Community-based form of security. Able to access an agent's MIB as defined by ACLs and passwords. Offer minimal security features. (No encryption or authentication.) Defined in RFC 1157 May 1990.  Wikipedia  RFC 1157       

Simple Network Management Protocol version 2c (SNMPvc2) Community-based form of security. Able to access an agent's MIB as defined by ACLs and passwords. Offer minimal security features. (No encryption or authentication.)   Wikipedia         

Simple Network Management Protocol version 3 (SNMPv3) Authenticates and encrypts packets between management devices. Defined in RFC 5590 June 2009.  Wikipedia  RFC 5590       

Simple Service Discovery Protocol (SSDP)  October 28, 1999  Wikipedia  IETF       

Simultaneous Peripheral Operations On-line (SPOOL) A buffer, typically for printers.   Wikipedia         

sine wave The most common AC waveform. 360° in each cycle. Voltage at any point along the waveform is equal to the peak (max) value × the sine of the angles of rotation. The average value is used when an AC sine wave is changed to DC.   Wikipedia         

single area OSPF Uses area 0. Good for small campus. Has a large routing table because summarization is disabled by default. LSDB. Frequent SPF algorithm calculations.            

Single Data Rate Synchronous DRAM (SDR SDRAM)    Wikipedia         

Single Page Application (SPA) Web application or web site that fits on a single web page with the goal of providing a more fluid user experience similar to a desktop application.   Wikipedia         

Single Point Of Failure (SPOF) Where there is no redundancy. If the device fails, the rest of the system is affected.   Wikipedia         

Single Root Input/Output Virtualization (SR-IOV) Network interface that allows the isolation of the PCI Express resources for manageability and performance reasons.   Wikipedia         

Single UNIX Specification (SUS) Standards required to qualify as "UNIX"     Wikipedia       

Single-board computer (SBC) All parts of a computer are on a single board. The Raspberry Pi is an example SBC.   Wikipedia         

Single-Mode Fiber (SMF) Commonly used as backbone cabling or cable in phone systems. Light travels straight down the fiber and does not bounce off the fiber walls. Can transmit 10Gbps up to 40 kilometers (25.85 miles).   Wikipedia         

Single-Serving Sites (SSS) A website that consists if a single page and has a single   isitchristmas.com         

site Physical collection of Active Directory (AD) objects defined by subnet.   Wikipedia         

site-to-site VPN An extension of a WAN. Connects entire networks together. Both ends of the connection know about the VPN in advance, but internal hosts are not aware of the tunnel. VPN gateway encapsulates and encrypts.   Wikipedia         

SkyDrive Microsoft's online file storage, now renamed to OneDrive. (see OneDrive)            

Skylake Microarchitecture codename from Intel. Announced August 5, 2015.  Wikipedia         

Skype A free softphone that uses proprietary protocols. First released August 29, 2003.  Website  Wikipedia       

slope m The steepness of a line.   Wikipedia         

SMB 2.0 (aka: SMB2) Introduced with Windows Vista in 2007.  Wikipedia         

SIGGRAPH 2018  August 12-16 in Vancouver.  Website         

Small and Medium-sized Businesses (SMB)             

Small and Medium-sized Enterprise (SME)             

Small Computer System Interface (SCSI)    Wikipedia         

Small Form Factor (SFF) Desktop computers with a small footprint. The Mac Mini is a good example of a SFF computer.   Wikipedia         

Small Form Factor 8639 (SFF-8639)    Website  Wikipedia       

Small Form-factor Pluggable (SFP)    Wikipedia         

Small Office/Home Office (SOHO)             

Small Outline Dual In-line Memory Module (SO-DIMM) (aka: SODIMM) Memory form factor roughly half the size of regular DIMMs. Often used in laptops, Mini-ITX motherboards, and office printers. All 64-bit modules have a single keying notch.

72-pin SO-DIMM older 32-bit
100-pin SO-DIMM older 32-bit, two notches
144-pin SO-DIMM single notch near the center
200-pin SO-DIMM (DDR/DDR2) single notch nearer to one side
204-pin SO-DIMM (DDR3) single notch closer to the center than on 200-pin SO-DIMMs
260-pin SO-DIMM (DDR4) 69.6 mm (2.74 inches) wide and 30 mm (1.2 inches) high, making them 2 mm (0.079 inches) wider than DDR3 SO-DIMMs, with a single notch after pin 144
260-pin SO-DIMM (UniDIMM), 69.6 mm (2.74 inches) wide and 30 mm (1.2 inches) or 20 mm (0.79 inches) high, with a single notch placed differently than on DDR3 SO-DIMMs

SmallBasic Programming language and IDE developed by Microsoft. Announced in October 2008 and released on July 12, 2011.  Wikipedia  Website  TechNet  Microsoft Blog   

Smalltalk Object oriented programming language.   Wikipedia         

Smart Jack Type of Network Interface Device (NID) that includes circuitry to perform such functions as converting between framing formats on a digital circuit (T1), remote diagnostics, and regenerating a digital signal.            

Smartsheet Management and collaboration Software as a Service (SaaS)   Website  Wikipedia       

SMB 3.0 (previously named SMB 2.2) Introduced with Windows 8 and Windows Server 2012.  Wikipedia         

SMB 3.0.2 Allowed SMB1 to be optionally disabled for increased security. Introduced with Windows 8.1 and Windows Server 2012 R2.  Wikipedia         

SMB 3.1.1  Introduced with Windows 10 and Windows Server 2016.  Wikipedia         

SMB1 (deprecated, aka: Common Internet File System (CIFS))   Wikipedia         

smurf attack Type DDoS attack where large amounts of ICMP packets are sent from a spoofed IP address on the network to the network broadcast address causing many replies. Originally written as smurf.c by Dan Moschuk, aka TFreak, in 1997.  Wikipedia  Hackepedia       

snapshot Quick point-in-time backup of critical virtual machine files used to restore the VM back to that point.   Wikipedia         

SNMP agent Software that runs on a managed device such as a server, router, or switch.            

SNMP manager (aka: Network Management System (NMS)) Runs a network management application.            

Snow Leopard (Mac OS X 10.6)   Wikipedia         

Snow White and the Seven Dwarfs Frist full-length animated feature film.  Produced by Walt Disney. Released December 21, 1937.  Wikipedia         

social media Tool for connecting and communicating with people.   Wikipedia         

socket The combination of the source and destination IP addresses and the source and destination port numbers.   Wikipedia         

Socket AM3 (941 pins) CPU socket for AMD processors. Supports DDR3 memory. Compatible with AM3 and AM3+ processors including Phenom II, Athlon II, Sempron, Opteron 138x. Released February 9, 2009 as the successor to Socket AM2+.  Wikipedia         

Socket AM3+ (942 pins) Modification of the AM3 Socket for CPUs based on the AMD Bulldozer microarchitecture. Retains compatibility with AM3. Also supports the Piledriver microarchitecture including the FX line and Opteron 3000 series.   Wikipedia         

Socket FM1 (PGA-ZIF, 905 pins) CPU socket used by AMD Llano processors such as early A-series APUs and Athlon II. Released July 2011. Succeeded by Socket FM2.  Wikipedia         

Socket FM2 (PGA-ZIF, 904 pins) CPU socket used by AMD Trinity and Richland APUs as well as Athlon X2 and Athlon X4. Released September 27, 2012.  Wikipedia         

Socket FM2+ (PGA-ZIF, 906 pins, aka: FM2b) CPU socket used by AMD Steamroller microarchitecture Kaveri and Godavari APUs. Supports Socket FM2 CPUs. Released January 2014.  Wikipedia         

socket pair the source and destination IP addresses and port numbers   Wikipedia         

socket.gethostname() Prints the hostname in python. import socket
   Python Documentation         

SoftEther VPN (Software Ethernet) First released January 4, 2014.  Website  Wikipedia       

softphone A phone that is not a phone.   Wikipedia         

software Set of instructions that control a computer.   Wikipedia         

Software as a Service (SaaS) (aka: cloudware) Software that is delivered form the web or "cloud". Gives access to applications through a subscription. Microsoft Office 356, Dropbox, and Google Docs are all examples of SaaS.    Wikipedia         

software attack Probe,            

Software framework    Wikipedia         

Software-Defined Networking (SDN)  Began shortly after Sun Microsystems released Java in 1995.  Wikipedia         

Software-Optimized Encryption Algorithm (SEAL) Alternative algorithm to software-based DES, 3DES, and AES. Stream cipher with 160 bit encryption key. Low CPU usage. Symmetric Developed in 1993 by Phillip Rogaway and Don Coppersmith.  Netacad         

SOH CAH TOA sin = Opposite/Hypotenuse, cos = Adjacent/Hypotenuse, tan = Opposite/Adjacent   Khan Academy         

solid figure A figure that lies in space.            

Solid State Drive (SSD) A storage media that uses flash memory and allows data to be accessed faster than a standard HDD.   Wikipedia         

SolidWorks CAD/CDE sofware.   Website  Wikipedia       

Sony Electronics manufacturer based in Tokyo, Japan. Founded May 7, 1946.  Wikipedia         

Sony Vaio 505  First released July 24, 1998.  Wikipedia         

Sony Xperia XZ Premium

  • 139 mm (5.5 in)
  • 3840 x 2160
  • 807 ppi
CPU: Snapdragon 835
GPU: Adreno 540
Memory: 4 GB LPDDR4X RAM
  • 64 GB
  • microSDXC up to 256GB
  • Rear camera: 19 MP
  • Front camera: 13 MP
Battery:3230 mAh
Dimensions:H: 156 mm (6.1 in) W: 77 mm (3.0 in) D: 7.9 mm (0.31 in)
Weight:195 g
Ports: USB 3.1 Gen 1 Type-C
 First released Febuary 2, 2017.  Website  Wikipedia       

Sony Xperia XZ2 Smartphone from Sony. Announced February 25, 2018 at Mobile World Congress (MWC) 2018.  Website         

SORT Command that sorts input.            

Sort-Object Used to sort objects in PowerShell.   TechNet         

source IP address Contains a 32-bit binary value that represents the source IP address of the packet.            

source MAC address Part of an Ethernet frame.             

source port The original protocol port that was used in in a data transfer.            

Southbridge    Wikipedia         

Space Exploration Technologies Corporation (SpaceX)  Founded May 2002.  Website  Wikipedia       

Spacewar! First game on the PDP-1 Released in 1962.  Wikipedia         

spaghetti code Code having a complex and tangled control structure. Usually involving many GOTO statements.   Wikipedia         

Spanning Tree Algorithm (STA) Determines the best paths to the root bridge in the broadcast domain.            

Spanning Tree PortFast BPDU Guard Enhancement (aka: BPDU Guard) Feature of the STP enhancement from Cisco that bypasses the spanning tree listening and learning process to speed up network convergence.    Cisco         

Spanning Tree Protocol (STP) 802.1D A legacy standard that runs all VLANs in a spanning tree instance. Developed to addresses the issue of routing loops. Ensures redundant physical links are loop-free. First standardized by IEEE as 802.1D in 1990. Original algorithm developed by Radia Perlman in 1985.  Cisco  Wikipedia  Cisco (Understanding and Configuring Spanning Tree Protocol)     

Spanning Tree Protocol Root Guard Enhancement (aka: root guard) Feature of the STP enhancement from Cisco that lets you administratively pick which bridge should be the root bridge. This works even if another switch is configured with a root priority of 0 and has a lower MAC address.   Cisco         

spanning-tree cost

syntax: spanning-tree cost (value 1-200,000,000)

SPDY      Wikipedia       

Special Interest Group on Computer GRAPHics and Interactive Techniques (SIGGRAPH) Annual conference on computer graphics (CG) convened by the ACM SIGGRAPH organization. First held in 1974.  Website  Wikipedia       

Spectre Breaks the isolation between different applications allowing an attacker to trick error-free programs. Reported January 3, 2018.  Website  Project Zero Blog  ZDNet  The Verge (Processor flaw exposes 20 years of devices to new attack)   

Sperry    Wikipedia         

Sperry Rand Sperry renamed itself Sperry Rand after merging with Remington Rand.   Wikipedia         

SPF Tree Created by the SPF algorithm. Used to calculate the best path to each node.            

SpiderMonkey JavaScript engine   Wikipedia         

split Split can separate files while cat can merge files.   YouTube         

Split Horizon Prevents routing loops in distance vector routing protocols. Does not allow advertisement updates to be sent back down the interface it was learned. Can cause problems for frame relay.   Wikipedia         

Splunk    Website  Wikipedia       

spoofing Masquerading as another entity, usually by spoofing an IP address, MAC address, or user.            

spool A buffer, typically for printers.            

Spotify An internet music streaming service.   Website         

SQL commands Can be divided into two overall categories: data definition language (DDL) and data manipulation language (DML) commands.            

SQL injection Inserting lines of SQL code into a query, typically on a web site, with malicious intent such as to delete a database or to reveal its contents.   Wikipedia         

SQL Slammer Worm Worm that exploited a bug in Microsoft SQL Server and Desktop Engine. Launcehed January 25, 2003.  Wikipedia         

Squirrel    GitHub         

ssh -p (port number between 1025 and 65536) (username@server ip address) Linux SSH login.            

SSH File Transfer Protocol (SFTP) (aka: Secure File Transfer Protocol) Secure file transfer protocol that uses SSH.   Wikipedia         

SSH forwarding Send another port over SSH.            

Standard ACL Permit or deny traffic only from source Layer 3 (IPv4) addresses. Should be placed close to the destination.            

standard error 2>            

standard input Comes from the keyboard by default. 0< (Shorthand: <)            

standard library Library made available across implementations of a programming language.   Wikipedia         

standard output Goes to the display by default. 1> (Shorthand: >)            

Standby Active Virtual Gateway (SVG) Takes over for the AVG if it goes down. Elected by next highest priority to the AVG.            

Standby Virtual Forwarder (SVF) When more than 4 gateways are in a GLBP group then the rest will be SVF.            

Star Wars Episode IV: A New Hope  Released May 25, 1977.           

Star Wars Episode V: The Empire Strikes Back  Released May 17, 1980.  Wikipedia         

Star Wars Episode VI: Return of the Jedi  Released May 25, 1983.           

StarCraft  Released March 31, 1998.  Website  Wikipedia       

START Starts a separate window to run a specified program or command.            

Start of Authority (SOA) Type of DNS record.   Wikipedia         

Start-Process powershell -Verb runAs Start PowerShell as Administrator.   StackOverflow         

startup configuration file Configuration file on network devices that is stored in NVRAM by default and accessed at startup.            

state table             

stateful firewall Filters traffic based on what is allowed to enter or exit an interface, without inspecting the traffic. Only packets matching a known active connection are allowed to pass the firewall. Monitors state of connection through SPI. Most common type of firewall. Developed by Bell Labs in 1989.  Wikipedia         

Stateful Packet Inspection (SPI) (aka: dynamic packet filtering)   Wikipedia         

stateful protocol Protocol that keeps track of the state of the communication session.            

Stateless Address Auto-Configuration (SLAAC) Method that allows a device to obtain an IPv6 prefix, prefix length, and default gateway address information from an IPv6 router without the use of a DHCPv6 server.    Wikipedia         

stateless application Application where data does not change.   TechTarget         

stateless firewall Blocking is based on Access Control Lists (ACLs) and defined rules. Can block and unblock by difined IP address, port access, or URL address.            

statement    Wikipedia         

Statement Handle (STH) ($sth)            

static NAT (aka: one-to-one) Statically configure the mapping of an inside local address (IP of internal server) to an inside global address (IP of server according to the internet).   Wikipedia  Juniper  Cisco     

Static Random-Access Memory (SRAM) (aka: Static RAM) Typically used as CPU cache memory. Faster than DRAM but more expensive and less dense. Does not need to be refreshed often. Type of semiconductor memory that uses bistable latching circuitry (flip-flop) to store each bit.   Wikipedia  Netacad       

static route Used to connect a specific network or to provide a Gateway of Last Resort. Have an AD of 1. They can be configured with the next-hop IP address (recursive static route), an exit interface (directly connected static route), or both an IP and exit interface (fully specified static route). Static routes are easy to implement in small networks. More secure and efficient than dynamic routes. Routes will always be the same and need to be changed manually as the topology grows/changes. To configure a static route use the syntax:

ip route [destination ip address] [subnet mask] [ exit interface | next-hop ip address ]


Statistical Time-Division Multiplexing (STDM) Uses a variable time slot where data can compete for a free slot. Developed to overcome TDM inefficiency.   Wikipedia         

Steam A gaming social network. First released September 12, 2003.  Wikipedia         

Steam Machine (aka: Steam Box) Game console from Valve. Released November 10, 2015.  Wikipedia         

SteamOS  Initially released December 13, 2013.  Wikipedia         

Steamroller Microarchitecture from AMD            

steganography hiding data in plain view in pictures, graphics, or text.    Wikipedia         

step-down transformer Lower secondary voltage than primary voltage.   Wikipedia         

step-up transformer Higher secondary voltage than primary voltage.   Wikipedia         

Steve Jobs Co-founder of Apple with Steve Wozniak. February 24, 1955 - October 5, 2011  Wikipedia         

Steve Wozniak Co-founder of Apple with Steve Jobs.   Wikipedia         

Stock Keeping Unit (SKU)    Wikipedia         

Stop-Process  Introduced with PowerShell version 1.0.  TechNet         

Storage Area Network (SAN)    Wikipedia         

storage medium Where data can be stored. (Hard Drive, Blue-Ray Disc, paper,   Wikipedia         

Straight Through Cable (T-568A or T-568B to itself) Most common networking cable. Connect from a host network interface controller (a computer or similar device) to a network switch, hub or router.    Wikipedia  LINFO       

Straight Tip (ST) (aka: stab and twist) Fiber-optic connector that uses a BNC attachment mechanism.   Wikipedia         

stream cipher Symmetric key cipher where plaintext digits are combined with a pseudorandom cipher digit stream (keystream).   Wikipedia         

Stream Control Transmission Protocol (SCTP) Transport layer protocol similar to TCP and UDP. Standardized by IETF in RFC 4960 September 2007.  RFC 4960  Wikipedia       

string Sequence of characters.   Wikipedia         

striping Writes segments of data across multiple drives.   Wikipedia  Netacad       

Structured programming    Wikipedia         

Structured Query Language (SQL) Special programming language made for databases. Not case sensitive but best practice is to write commands in all-caps.   Wikipedia  W3Schools  Khan Academy     

stub network Router that is connected to a single router.   Wikipedia         

stutter calls itself twice.   Wikipedia         

Stuxnet Worm that targets PLCs. Discovered in June 2010.  Wikipedia         

sub HTML tag for subscript text.   W3Schools         

Submarine Telegraph Company Ran the first telegraph cable between England and France. Operaional November 13, 1850.  Wikipedia  HistoryofInformation.com  This day in Tech History     

subnet Physical segment in a Active Directory TCP/IP network.   Website  Wikipedia       

subnet ID Part of an IPv6 global unicast address. Organizations use this to identify subnets within a site.   Wikipedia         

subnet mask (netmask) Logicaly subdivides a network. Identifies what part of an address is the network portion and what is the host portion.   Wikipedia         

subnet zero The first subnet obtained after subnetting the network address.   Wikipedia  Cisco       

subnetwork (subnet) Logical subdivision of an IP network into two or more smaller networks.   Wikipedia         

subquery Query linked to another query.   Wikipedia         

Subscriber Connector (SC) (aka: square connector) Latched fiber-optic connector. Works with either SMF or MMF. Not as popular as ST connectors for LAN connections.   Wikipedia         

Subscriber Identity Module (SIM) (aka: sim card) Developed in 1991 by Munich smart-card maker Giesecke & Devrien.  Wikipedia         

SUBST DOS command that associates a path with a drive letter.            

substitute user (su) Execute a command as another user.            

Substitution (Caesar cipher) Shifts the alphabet. Retains letter frequency.             

sudo    Website         

suite Collection of software sold as a package. i.e.: Microsoft Office            

summary route Can help minimize the number of static routes in the routing table. IPv6 addresses can be summarized into a static route if: 1) the destination networks are contiguous and 2) the static routes all use the same exit interface or next-hop IPv6 address.   Wikipedia         

Sun Microsystems Bought by Oracle in 2009. RIP :(   Wikipedia         

sup HTML tag for superscript.   W3Schools         

Super Mario Run Mobile game made by Nintendo. Released December 15 2016.    Wikipedia       

Super Nintendo Entertainment System (SNES) (aka: Super Nintendo) Video game console made by Nintendo. First released in Japan November 21, 1990.  Wikipedia         

super-server Type of daemon on UNIX.   Wikipedia         

supercomputer Many processors connected together (either distributed or cluster) to solve complex problems.  First designed by Seymour Cray in the 1960's  Wikipedia         

supernet route A routing table entry with a subnet mask less than the classful mask. (summary address)   Wikipedia         

supervisor password Restricts access to the BIOS setup utility.            

Supervisory Control and Data Acquisition (SCADA) Used to manage Heating, Ventilation, and Air-Conditioning (HVAC) and other types of industrial and environmental systems.   Wikipedia         

Surface Book 2 Laptop from Microsoft. Announced October 17, 2017. Available for pre-order beginning November 9, 2017. Shipping November 16, 2017.  Website  Wikipedia  Windows Blogs     

swap (aka: virtual memory) Minimum recommended size of 256 MB.   Wikipedia  Red Hat  Ubuntu Help     

Swift Programming language developed by Apple. Announced June 2, 2014.  Wikipedia  Website       

switch Network device that typically operates at OSI Layer 2, Layer 3, or Layer 7. Provides centralized connectivity similar to hubs. Forwards data only to the device(s) that need to receive it based on the Layer 2 header. Filters MAC addresses and builds a MAC table. Switch has ports, router has interfaces. Can operate with or without VLANs. First Ethernet switch was introduced by Kalpana in 1990.  Wikipedia  Network Computing archive       

Switch Virtual Interface (SVI) logical interface associated with a VLAN. Can allow for remote switch administration. Used to assign an IP addresses to a Layer 2 switch where no physical interface for IP is available.            

Switched Port Analyzer (SPAN) Copies packets to another port on the switch to analyze.            

Switched Virtual Circuit (SVC) Established dynamically by sending signaling messages to the network (CALL SETUP, DATA TRANSFER, IDLE, CALL TERMINATION).   Netacad         

Symmetric Block Ciphers Encrypts in blocks, typically 64 bits for DES or 128 bits for AES. RSA has a variable block size. Output may be larger than the input to match the block size.   Netacad         

Symmetric DSL (SDSL)    Wikipedia         

symmetric encryption algorithm (secret keys) Uses a single key to encrypt and decrypt data. 80-256 bits. Most common because of shorter key length. Uses block ciphers and stream ciphers. (DES, 3DES, AES, IDEA, RC2/4/5/6, and Blowfish)   Wikipedia         

Symmetric Stream Ciphers Encrypts one bit at a time. Technically a block cipher with a bit size of one bit. Faster than block ciphers and generally don't increase message size. Examples include The Vigen   Netacad         

SYN/ACK Packet sent in response to a SYN packet.    Wikipedia         

Synchronous With clock rate.            

Synchronous Code-Division Multiple Access (S-CDMA)             

Synchronous Digital Hierarchy (SDH) European-based ETSI and ITU standard. Uses optical (fiber) to transmit data over a WAN connection.   Wikipedia         

Synchronous dynamic RAM (SDRAM)    Wikipedia         

Synchronous Optical Networking (SONET) ANSI standard. Uses optical (fiber) to transmit data over a WAN connection. (155.52Mbps)   Wikipedia         

syntax Proper "grammar" for code. The correct arrangement for a command or line of code.            

SYS    Wikipedia         

syslog (UDP port 514) Standard for a separate central log server on UNIX-like systems. Levels include:

0 Emergency Most severe error condition, which render the system unusable
1 Alert Requires immediate attention
2 Critical Less-severe condition. Should be addressed to prevent service interruption.
3 Error Error condition with the system that do not render the system unusable.
4 Warning Notification that specific operations failed to complete successfully.
5 Notification Non-error notification that alerts an administrator of state changes.
6 Informational Detailed information about the normal operation of a system.
7 Debugging Highly detailed information (i.e. info on individual packets) typically used for troubleshooting.
   Wikipedia  YouTube       

syslog facility level Default is local7            

System Call Interface (SCI) API for the Linux kernel.   Wikipedia         

System Configuration (MSConfig) Tool that can help identify problems that might prevent Windows from starting correctly.   Wikipedia  Microsoft       

System Development Life Cycle (SDLC) Five phases: initiation, acquisition and development, implementation, operations and maintenance, and disposition.   Netacad         

System LifeCycle (SLC) The system lifecycle (SLC) should provide valuable guidance on the best practices that need to be followed throughout the network.            

System Management Basic Input/Output System (SMBIOS) (System Management BIOS) Introduced in 1999.  Wikipedia         

System Management Controller (SMC)             

system of equations Set of 2 or more equations.            

system of linear equations (aka: linear system) Collection of two or more linear equations involving the same set of variables.   Wikipedia         

System on a Chip (SoC) (aka: System on Chip) An integrated circuit with all components of a computer.   Wikipedia         

System Preparation Tool (Sysprep) Tool from Microsoft used for Windows deployment. Can modify an image before committing the final clone.   TechNet  Wikipedia  Netacad     

System Shock  Released September 23, 1994.  Wikipedia         

System Shock 2  First released August 11, 1999.  Wikipedia         

Système International (SI) (aka: International System of Units or metric system)   Wikipedia         

systeminfo Command that displays the system information of a Windows based system.            

Systems Network Architecture (SNA) IBM's proprietary networking architecture. Created September, 1974.  Wikipedia