Open Network Linux Alternatives

Cumulus Linux is a powerful open network operating system that comes with a powerful way to automate, customize, and scale your data. By using an industry-standard Linux OS in its 100% open source network operating system, you have the power of flexibility to create the ideal network that works best for your business. You can use containers with your public cloud provider or leverage them to build a private cloud for your enterprise. This innovative open network operating system streamlines the way for easy implementation, management, customization, and scalability. Complete standardization, network protection, flexible open architecture, reduced OpEx, end-to-end automation, fast IT delivery, and more are the reason to choose this modular network operating system.

SONiC is an open source network operating system that is specifically designed for the networking world and tailored for networking applications at the data center layer, the edge, and the campus. It is based on Linux that runs on switches from multiple vendors and ASICs. It is designed to solve the problems of interoperability and vendor lock-in. It makes it as easy as possible to get going, with as few prerequisites as possible and as little of a barrier to entry as possible.

It is written in a way that makes it easy and simple to add additional capabilities. You can add a feature, like BGP or STP, or you can take the whole switch and turn it into a router that does whatever you need. SONiC has a number of features to help it operate and control the underlying hardware in a network switch. This open platform allows you to do what you want with your switch instead of being limited by the vendor’s customization. It bids teams the flexibility to create network solutions tailored to their needs while providing the overall capability to handle a large ecosystem and community.

DriveNets Network Cloud is cloud-native software designed from the ground up to separate control from data-plane functions and to make the network resources. This innovative architecture delivers flexibility, simplicity, and security, resulting in increased productivity, better uptime, and reduced cost of ownership. It enables service providers to dynamically share bandwidth and other network resources between different services. With it, providers can fully utilize their network, increase network capacity and reduce operational costs.

Network operators can therefore focus on the business of their core competency and have their network customized and optimized by a third party with agility, efficiency, and transparency. DriveNets Cloud is the revolutionary software that turns the physical network into a shared resource supporting multiple services. It starts with mapping the real network, modeling its intricacies and capabilities, and then automatically creates a separation of services that isolates the traffic to insure optimal QoS for each flow, enabling multi-tenancy and self-service capabilities.

CloudView NMS is a smart way to crawl the various networks by monitoring the performance or efficiency of networks with auto-discover or detecting the SNMP, TCP, or Internet protocols. It has been developed as a scalable-oriented platform that supports a network of any size with Linux, Mac OS, Raspberry Pi, and Windows. The users can get a complete overview of networking with a geographical view or a huge number of internet protocol nodes.

Full FCAPS functionality per TMN standards can be retrieved for working for the small or big enterprise level with multiple level network compatibility. A complex distributed system for various remote users can be made compatible with the GUI application as a standalone feature. The key features are following detailed overview of the network, 24 x 7 efficacy, auto-discovery, report the faulty ports, graphical link representation, IT automation engine, multiple user profiles, unlimited number of SNMP probes, TFTP client, Email/SMS alerts for error detection, and IP address management.

The Dude is a network tracking program that allows navigating the connections among different devices by randomly improving the efficacy of the overall network setup. When any fault or systematic error occurs, it instantly warns by sending alert notifications for fixing the problem. The program has been developed to automatically scan the different gadgets off the collaborative domains. It helps draw out a map with certain layouts of the different connections by analyzing the string of the collective mode.

The users can discover the various types of brands with diverse features and monitor the individual link compatibility by analyzing the graphs. The Dude has the following key features like custom icons, SVG icons for devices, add custom devices, remote Dude server & local client support, easy installation, custom background, Runs in Linux Wine environment, Windows, macOS Darwine, ICMP, SNMP, DNS, and TCP monitoring for devices that associate them.

Pandora FMS is a customized tracking program that allows identifying the various computer networks like SAP environments’ indication. It is highly flexible that can be made compatible with approximately all the operating systems, and supports the remote tracking of various programs like UDP, ICMP, HTTP, WMI, SNMP, and TCP. It utilizes multiple parameters for highlighting the efficiency of various operating systems, applications, servers, and hardware as well just like the proxies, firewalls, web servers, routers, or databases.

The platform is accessible via different servers for integrating suite, and the predictive server option allows testing the replicate data between various sites or SNMP Trap console. Following are the salient features of this platform: SAP monitoring for preconfigured checks, enterprise monitoring data, optimization of the status of working gadgets, single platform controlling of diverse connections, synthetic overview for underpinning the business, collection of data from IT sources, log collection for unified centralization, and checking the status of different mediums at the same time.

cStatus is a smart program that is used to monitor or scan a network in a particular system by elaborating the complete analysis or performance of the systematic domains. A graphical traceroute displays the route by processing the network among various computers, and time spent by each hop can be estimated or shown with complete stats. The users can check the LAN connectivity by exploring the cStatus, and it contains a simple window with a comprehensive layout for checking the hostname or connection type.

There are some valuable features like TCP port monitoring (TCP ping), ICMP ping monitoring, comprehensive alarm system, statistical information, host display for filter the system, MAC vendor detection, MAC information, hostname extraction by changing the DNS mode, IPs detection, and port scanner.

CloudRadar Monitoring is a SaaS server-based program that allows tracking the various devices with systematic specifications like host, server, computer, IP-camera, switch, or router with a connective system. The users can get a complete overview of servers by analyzing the detailed insights with operating functionalities like memory management, disk fill levels, CPU usage, network bandwidth, or other system processes.

It provides great comfort to the users by saving precious time for configured-based monitoring solutions. The platform provides multiple metrics or sensors for each host, and comprehensive checks can be applied to HTTP, ICMP, or content with unified centralization of all the insights. Its unique features include the following: Windows & Linux, alerts notifications for websites (intranets, servers, or any device), tracking of complete information technology with easy to complicated modes, Internet monitoring for checking the connected web servers or email server, routers’ info, IP-cameras, printers, or other gadgets with firewall.

OpenNMS is a comprehensive solution for monitoring the network in an organization of different gadgets or devices. Subscription-based access is required for interacting with the complete features, and anyone can check the performance or current status of operating. There are multiple public sectors or private networking domains that can be analyzed, such as education, govt, finance, tech, healthcare, energy, industry, or retail, and many more. It is a highly configurable program that detects each unique data with the sequence of time and efficiency for processing large scalability.

OpenNMS includes some valuable options for having a great experience like thresholding, network traffic analysis (flows) with complete descriptions, application monitoring (STM or digital experience (DEM), asynchronous detection, complete ticketing system integrations. There are some salient features of this platform, such as the flexible specifications for collecting the frameworks of data workflows with seamless integrations, advanced scalability for interpreting the huge data distributions, efficacy to operate an open-source solution.

Trafikito is an extensible tracking platform that is used to monitor the networking efficiency of various devices with complete performance or status indications. It is based on the distributive system that serves worldwide services by running through global AWS cloud infrastructure. It is integrated with different platforms for securing the data, such as Amazon web services, Cloudfront CDN, Cloudfront DNS, DynamicDB, EC2, etc.

For complete access to the program, it requires an email or password for inserting the login besides the Google login option or email recovery options with password links as additional features. The default graphic indicators display not only the working efficacy of the various storage specifications but also the comparisons between storage or processing speed for stable networking. The platform is embedded with a simple-to-use or intuitive interface that displays the performance indications of different specifications like RAM, SWAP, Disk availability, CPU processor, and average load management, etc.

Advanced Host Monitor is an effective management program that allows tracking the performance or efficiency rate of different devices in a systematic domain of one centralized network group. This is a highly extensible or customizable platform that is recommended for dealing the small and mid-level enterprise solutions. Various customized profiles are integrated for elaborating the performance results, and that can be retrieved as a variable report.

Multiple log files are created by following the different levels or formats, such as Text, HTML, DBF, or ODBC, and tests can be performed online or with the installed program with instant results. Different systematic errors or faults have been highlighted with the help of this program, and it notifies the main administrator with alert notifications in case of any problem with a recommended solution. Approximately one hundred and forty plus tests can be organized for analyzing the networks by checking the different parameters of servers with complete stats.

NetXMS is a general public license-based platform that allows monitoring the network system of various gadgets or devices’ combinations in an effective way. It is highly configured with administrative or tracking functions like Eclipse or Web GUIs and provides emails or SMS notifications in case of any error or fault detection. The platform enables users to manage the various objects in a certain sequence for highlighting the connectivities among different strings in a network.

The platform has been developed for detecting information technology with all of the components and a built-in scripting engine for the latest automation. There are some valuable features of this platform, such as the detection of various servers or domains, data extraction from NetXMS agent or SNMP compatible mode, centralized remote agent updates, OSI Layer 2 & Layer 3 IP topology automatic discovery mode, Portable client library (C and Java APIs), extensible processing, remote strategies, automatic configuration option, etc.

SentinelAgent is a highly scalable SaaS tracking solution that allows monitoring networks of MS systems like Exchange, Server, Windows, and SQLServer or MS Dynamics by securing the complete logs overview. It is a great solution for managing small and mid-sized enterprises by analyzing the technical procedures for integrating with cloud storage.

The users can ask for getting the multiple tracking solutions by entering the email and click for send me the link option. Following are the key features of this platform, such as performance metrics or system inventory in real-time insights with a various number of Windows PCs, compatibility with tablets or servers in the network, Event Log Monitoring, cloud-based infrastructure, preconfigured notifications, customizable alert options, system memories, or easy to install program.

OP5 Monitor is a network monitoring management platform that displays the performance or efficiency rate of internet networking systems of different organizing server domains like health, energy, IT, industry, or many more. Complete IT estate can be tracked with the help of unified glass-based technology for detecting the adjacent components. The platform is embedded with advanced techniques that provide the additional layers of complexity for managing the dynamic or static overview with full insights. The users can get detailed detecting reports with visual representations and data collected with tech stack or across hybrid collaborations.

It is embedded with unique plugin tools with kubernetes cluster components like replicas, pods, or nodes, and special plugins have been added for monitoring the Amazon Web Services resources. Key features comprise of the following: a distributed framework to tackle the mode of any scale, full analysis of entire IT estate, additional plugins are compatible with Nagios plugin tools, SNMP network monitoring, and API monitoring.

Zenoss Network Monitoring is a great domain or server connection management platform that provides a complete overview for tracking the network both as virtual and physical networks with a complete analysis of data insights. All the data has been combined for one centralized platform for extracting the various indexes or correlating the cohesive data management with the latest plugin tools. The users can get alert notifications when a system detects any fault or error and suggest the best solutions for fixing the issues.

It specifies the valuable networking characteristics, such as unified detection, processors, cards, ports, power supplies, NFV infrastructure, IP address management, and suppression of symptomatic events. Following are key features of Zenoss: real-time cloud or on-premises infrastructure solutions, advanced methodologies to detect the IT connections, combine insights from logs, artificial intelligence navigation or referencing for various networks, proprietary log files, collect metrics, events, streaming or modeling the information with all cloud compatible components.

LogRhythm NetMon is an artificial intelligence-based platform that allows monitoring the network by engaging the various gadgets or servers like the data of healthcare, govt, utilities, financial services, legal, or manufacturing browsing domains. For complete access, you need to enter the full name, email, company name, job title, phone number, or country name for getting download the links.

The users can detect the various networking domains by analyzing the real-time insights with complete traffic analytics, and comprehensive support from the expert team can be taken for managing the complex networking solutions. Following are the key features of NetMon: detection of unauthorized or unwanted applications with the help of its algorithms, understand the network with Layer 2-7 visibility, the instant recognition of hang network with lateral movement, identification or prevention of sensitive data loss, and expedite network layer forensic analysis or discoveries.

10-Strike Network Monitor is a smart management platform that allows detecting the servers, switches, UPS, and many others gadgets in an organized way. Changes via different devices’ graphs can be analyzed with complete stats or systematic reports, and the checks can be integrated into the centralized platform for distributing the remote network commands. It processes the basic domains for network equipment by interpreting the SNMP, ICMP, TCP protocols, and space can be controlled for generating the background monitoring efficacy.

The platform is embedded with a comprehensive interface for analyzing the various stats of components available via internet protocols. The program provides the commands for managing the hosts, disks, services, databases, or other programming codes. Features include an overview of managed switches, CCTV systems, IP cameras, DVR or NVR, printers, HDD SSD MVMe disks, 24/7 mode alerts for generating real log updates, network devices, multiple checks options for detection, and statics or parameter charts.

Intermapper Network Monitoring Software is a management platform that is used to detect Internet protocols by integrating the various servers, websites, domains, or other network software. Different sectors like energy, data of healthcare, govt, utilities, financial services, legal, or manufacturing browsing domains can be analyzed with real-time insights. The users can draw the map for detecting complete network protocols, and alerts have been received with email or SMS for overall IT infrastructure management. Following are the options that can be utilized via this tool like Servers, Endpoints, Applications, Wireless devices, Facilities systems, Industrial equipment, Switches, firewalls, Environmental sensors, and telecommunication devices.

There are multiple options for drawing the layouts for innovating the functionality, and the platform can be managed with Linux, Windows, or Mac. In case of any confusion or support requirement, anyone can take assistance directly from the expert team for organizing the insights and network typologies. Its features include automatic mapping with a sequence drawing, proactive detection with color-coded icons, smart alerting, metrics planning, and an informative dashboard for viewership.

Xymon is an open-source monitoring system that is designed for your Windows, Linux, and Mac OS X devices. The software is providing complete support to you with the ability to display the health status of your servers with little or no effort on your part. This open-source software is offering you comprehensive data storage and some alerting abilities as well.

Xymon is also facilitating users with its plugins for monitoring specific areas, including file systems, processes, websites, databases, and more to add. The software is completely scalable for your needs, and data Data is stored in files that can be easily moved between different platforms. Complete host monitoring, test conducting ability, HTTP client performance, Java embedded, SNMP devices, email messaging, distribution support, and more to add.

ScienceLogic SL1 Platform provides you with a single dashboard to view all the metrics across distributed and multi-cloud architectures and helps with the describing of data via relationship mapping. You can act on the gained knowledge through automation and integration. You can share and integrate data across technologies and the IT ecosystem in real-time. Implement multi-directional integrations for the automatic fulfillment of proactive and responsive actions at the cloud scale.

You can comprehend the associations between business services, infrastructure, and apps. This content can be used to get access to data-driven insights. Explore and learn about each and every component existing in the enterprise across cloud, physical and virtual. Gather and save multiple data types in a concise and normalized data lake. The AIOps capabilities of the solution include IT Workflow Automation, Hybrid Cloud Monitoring, ITSM Workflow Automation, and Business Service Visibility. The platform takes care of your needs by offering tools to enhance service visibility and automation of IT workflows for the illustration of business impact.

OpenNMS is an Open-Source and top-level Network Management Platform. It assists you with the tracking and visualization of all the distributed and local networks. It provides in-depth traffic, fault, and performance monitoring with alarm generation in a single place. You can customize various aspects and scale them according to your needs. The best feature is that it is capable of integrating with your essential business workflows and applications.

The solution has six modules, each designed to help you with a different kind of situation. The flexible provisioning system delivers several methods for you to operate jointly with configuration management systems. The tool performs well with several industry-standard data collection protocols without the need for maintaining or writing third-party plugins. The supported protocols include Prometheus, SNMP, SFTP, WS-Management, WinRM, HTTP, SQL, and XML. Maintain undivided attention over the service’s availability and latency from different viewpoints through the OpenNMS Minion. Other highlights include enterprise visualization and reporting, scalability, robust configuration, and robust traffic management.

CANopen is a popular standardized embedded network composed of profile specifications and protocols. It offered many configuration capabilities and was developed to work with motion-oriented machine control systems like handling systems. It has evolved since its foundation and is now utilized in different application fields like building automation, medical equipment, railway applications, and maritime electronics.

The network reduces the responsibilities on the shoulders of the developer by automating several tasks. You get access to communication objects for network management data, time-critical processes, and configuration. Device designers can apply the essential network behavior to a device by using the offered communication objects. These assist designers in the making of devices capable of communicating process data, controlling the behavior of the network, and illustrating device error conditions. There are three logical parts to any CANopen device. The stack takes care of the communication through the CAN network, while the interface and the internal control functionality to process hardware interfaces are made possible by the application software.

Nagios Network Analyzer is a multi-featured Netflow Analysis, Bandwidth Usage, and Tracking solution designed to help you keep an eye over all the nodes in the network from any location. It delivers a detailed visual overview of the whole network traffic sources and potential security issues, enabling system administrators to collect high-level details instantly and take active steps the elimination of problems.

The intuitive and robust web GUI makes your experience worthwhile. The tool works with the official network monitoring software called “Nagios XI,” resulting in the consolidation of notifications and alerts while also keeping the network safe and secure. The administrators can lessen the burden on their shoulders by enabling alerts and including sources via the intuitive wizards in just a couple of clicks. The alerts are sent when abnormal activity occurs or when bandwidth usage crosses the specified limits. Other key features include Specialized Views, Advanced User Management, Custom Application Monitoring, and Advanced Visualizations.

Flowmon Platform allows you to accelerate network and security performance in a single place. You can use it to avoid network breaches, issues and give prompt responses to security problems with one security, performance, and network traffic analyzer designed to be used in all environments, including hybrid and cloud. Decrease the security gap between endpoint and perimeter by taking advantage of the ML technology for the detection of anomalies lying deep within the encrypted traffic.

Run diagnostics on the performance of the apps and network, no matter their location. Monitor the main issues, troubleshoot quickly and stop latency issues. The platform offers complete prevention of ransomware by employing more than 40 detection methods and over 200 algorithms to examine modifications in network traffic and relearning the harmful activity of harmful entities working in the network.

Splunk Infrastructure Monitoring enables IT Pros to boost performance with complete visibility, no matter the location. You will get the same unaltered performance in all environments like on-prem, multi-cloud, or hybrid systems. It offers continuous infrastructure troubleshooting and monitoring for any environment. The highlights include analytics, scalability, and speed that help with the modern monitoring in the cloud.

Leverage the presence of more than 200 integrations for cloud services alongside out-of-the-box dashboards for an instant view of the whole stack. Browse, Autodiscover, breakdown systems, clouds, and systems. Take the necessary before the performance start affecting the user experience through real-time actionable alerts. The platform quickly and precisely alerts on complex rules, multiple conditions, and dynamic thresholds to mitigate alert storms and decrease the detection time. Assess the speed and other performance metrics across 100,000 ephemeral modules, several deployment environments, and billions of events. Other highlights of the tool include Boundless scale, Advanced Kubernetes Monitoring, Single Pane of Glass, Full Stack Visibility, and Real-Time Streaming Analytics.

Obkio is a high-performance and multi-featured network performance diagnostic and monitoring solution built with IT professionals in mind. It regularly tracks the network performance through synthetic traffic to imitate the experience of the end-user in real-time and identify unresolved issues that you may have trouble finding manually. The tool deploys monitoring agents at various ends of the network and builds the best end-to-end monitoring app for pinpointing network issues anywhere in the network.

You will receive automatic alerts for network threats that degrade the end-user satisfaction success as jitter, huge packet loss, or jitter the moment they occur. The solution is packed with many features not found in traditional monitoring tools. These include End-to-End monitoring, Identifying the location of the problem, anomaly detection, public monitoring agents, ease of use and fast deployment, and 24/7 VoIP Quality Monitoring. You can streamline and reduce the complexities in the troubleshooting phase by identifying if the problems came to pass, their location, and the timing of their occurrence.

Cisco Network Assistant reduces the complexities that arise in managing a wireless network of up to 80 devices. It provides you with an intuitive and user-friendly UI for viewing all the information and interacting with it. The solution is enhanced to implement common services across access points, cisco switches, wireless controllers, and routers.

The network administrators can gain a consolidated view of the network with the help of this solution. They also have the power to use the capabilities and features across different Cisco products. There are multiple benefits offered to you. These include inventory reports and health tracking, front panel view of stacks, devices, clusters, and troubleshooting of network problems. You can also configure the cisco products as per the needs of the business. The tool will send alerts and event notifications to inform about the network errors crossing the threshold.

Network Bandwidth Analyzer is an all-in-one network bandwidth analysis and performance tracking solution. It allows you to identify, troubleshoot, and fix any issues in network performance. You can view various metrics like uptime, response time, and availability of switches, routers, and other SNMP-enabled devices. Analyze and monitor the network traffic patterns and bandwidth performance.

Other highlights include the Enterprise Command Center and the visualization of hop-by-hop analysis of various devices. One of the core features is that you get comprehensive performance management and fault monitoring for your network. You can decrease the network outages and instantly pinpoint, diagnose and repair multi-vendor network problems with an inexpensive network monitoring solution. Lower the number of undesired network alerts by defining alerts based on complex or simple nested trigger conditions. Other characteristics of the solution include Optional Enterprise Operations Console, Network performance baselines, Optional High Availability, and Optional Scalability Engine.

Azure Network Watcher provides multiple features to help you visualize key parameters, track, troubleshoot, and activate or deactivate logs for resources in an Azure virtual network. The purpose of the solution is to help you keep a watchful eye over the network and fix the health of IaaS products that encompasses Load Balancers, Virtual Machines, Application Gateways, Virtual Networks, and others.

The best feature is that you can view loads of resources in the virtual network and their associations. The monitoring of the bulk of resources is a difficult task, and it becomes a headache to find how they relate to each other. The topology module produces a visual illustration describing the resources and the connection between the resources. Other highlights of the platform include viewing security rules for a network UI, capturing packets to and from a VM, and diagnosing outbound connections from a VM.

SevOneIncSevOne offers state-of-the-art analytics and monitoring to assist managed service providers and enterprise carriers in assessing the speed and quality of their network. The highlights include Tool Consolidation, Alerting, ITSM Integration, Capacity Planning, New Service Rollouts, and Network Troubleshooting and Monitoring. You can enjoy network performance management for the present, the future, and the existing hour.

Unlock full views of backhaul networks, 4G/5G, Cable, and NFV via Carrier Networks. You can gain complete insights into switching, Wi-Fi, and Routing through Enterprise Campus Networks. Other features and capabilities include Network Streaming Telemetry, Enterprise Branch Offices, and Multi-Cloud Data Centers. You can use the Network Monitoring and Troubleshooting guide to gather data from the latest network device, find more information about the normal behavior in the environment, and view metrics and alert status across sophisticated and big networks. It gathers data from a timestamp, if there is one, before extracting and enriching that data for the enablement of great business outcomes.

Aruba AirWave is a powerful, feature-rich, and flexible multi-vendor wireless and wired network management solution designed for anyone searching for AIOps, unlimited scale, and more. You can switch to Aruba Central and experience and use the rich set of tools it offers. It reduces the complexities that arise in campus networking. Handle several generations of wireless access points, switches from any vendor while receiving granular visibility across the entire infrastructure.

IT teams can instantly monitor and fix issues impacting the user experience through simulated client testing and custom alerts that assist with the elimination of future performance issues. Prevent negative performance from reaching critical apps via better visibility into the usage and performance of web and mobile apps. This way, you can secure business traffic by immediately taking steps against malicious sites and restricting Wi-Fi consumption by app category.

NetBrain Enterprise Suite is the best-in-class and the only intent-based network automation tool available in the industry for resolving core problems troubling many enterprises in the modern world. These issues include the huge amount of network service requests and resources and time consumed for fixing them. The second concern is the proliferation of performance degradations and service outages due to errant or manual change processes.

The software is packed with a wide range of features like Traffic path Analysis, Deep network Discovery and Benchmark, Traffic Path Analysis, Automation Procedures, NetBrain for Collaboration, Advanced Configuration and Routing Management, and Map-Driven Change Management. With Automation Procedures, you can fulfill many tasks automatically. NetBrain comes in handy for design review, operational hand-over, and troubleshooting escalation.

NetBeez Network Monitoring provides Network Monitoring from the lens of the user for quick insight and resolution. It helps you maximize IT Support and Network Troubleshooting. The older and slower network monitoring tools only tell about the device status and are unable to identify end-user performance problems. With the help of this solution, you can keep an eye on the network from the end-users point of view, end-to-end, increasing availability and performance.

Use the dashboard to visualize historical and real-time network performance data from public clouds, remote locations, and users. The troubleshooting time is decreased by a great margin, thanks to the active and distributed network monitoring agents. The highlights of the solution include WAN and SD-WAN Monitoring, Wi-Fi Monitoring and Assurance, Hybrid Cloud Performance, and WFH Network Monitoring.

Riverbed NPM is an integrated infrastructure and network visibility solution designed to help you instantly troubleshoot issues and keep an eye on them. The goal is to simplify the monitoring and diagnosing of issues and run an analysis of what’s happening behind the scenes. You can use the powerful and high-performance NPM solution to resolve network-based performance problems.

It is programmed to collect all device metrics, flows, and packets. This job is performed on all environments like cloud, on-premises, and virtual to allow business-centric views for all the domains. You can gain a deeper understanding of the effect of network performance on crucial business initiatives by integrating with application performance monitoring and end-user experience. The key features include Elimination of the finger-pointing and the Removal of cloud blind spots.