Access Control List Linux:How Much Do You Know?

Traditional Linux networking is satisfied for most situations when employed in network switch, router or other network devices. However, it still has some limitations such as the problem of UNIX file permissions, which affects network security. Luckily, Access Control List (ACL) has been developed, which is designed to make a flexible permission mechanism in Linux. Well, what is ACL and how to use it in Linux?

Access Control List Overview

Access Control List is a list that grants or denies permissions to the data, which tries to access services attached to that network hardware such as Gigabit Ethernet switch or router. There are several types of ACLs such as access ACL and the default ACL. The former is the access control list for a specific file or directory and the later can only be associated with a directory.

ACL provides an additional, more flexible permission mechanism for file systems. To be specific, it ensures security by blocking packets that are destined to sensitive areas in the network. Based on the protocols, it also determines the type of traffic to forward. And it is also able to deny certain users or groups access to the Internet while allowing others. What’s more, ACL can block specified traffic, which greatly helps enhance the performance of your network.

How to Use Access Control List in Linux?

Usually, there are mainly four steps for the Access Control List configuration.

Installing ACL Package

Before using ACLs for a file or directory, you should install the acl package.

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Configuring ACL

1.Mount the file system consisting of the file or directory with ACL support. Here is the syntax for you to mount a local ext3 file system.

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2.Use the getfacl utility to show a file’s ACL.

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When a file does not have an ACL, it shows the same information as ‘ls –l’, although in a different format.

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3.Use the setfacl utility to add or modify one or more rules in a file’s ACL.

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If a file has an ACL, ‘ls –l’ will display a plus sign (+) following the permission.

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Remove ACLs

1.Use the “-x” option without specifying any permissions to remove rules for a user or group.

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2.Use the “-b” option to remove ACL itself.

access control list
Setting the Default ACLs

Add “d:” before the rule and specify a directory instead of a file name. Then the setting is completed.

What Is Linux ACL Mask and Why Does It Exist?

When setting the default ACL in a directory, some users may be confused to see “default:mask” or just “mask”. Actually, the “mask” is a mask setting, which is used to mask out permissions. Except a file owner or an “other” entry, “mask” is the maximum permission granted by access control entries for users and groups. The “default: mask” on a parent directory is also a mask setting, which is applied to things that are created within it.

Conventionally, people use the traditional Unix applications to run “chmod(…,000)”, which is expected to deny all access to a file. However, it fails unless there is a mask and the old “S_IRWXG” permissions map to it. Although having been upgraded several times, traditional Unix scripts still can’t work perfectly without a mask. In ACLS, the mask is also necessary. Without it, setting the file permissions to a entry such as “000” wouldn’t affect any non-owner user or group entries and other users still have access to the object. What’s more, without a mask, other approaches have defects in granting or denying permissions to the data as well.

mask

Figure 1: “mask” and “default: mask” scenario

Conclusion

From all the above, you may have a general understanding of Access Control List Linux, Linux ACL Mask and how to use ACL in Linux. The use of ACL in the Linux OS is important to the security of network. Recently, FS has teamed up with Cumulus to provide the N-series open networking switch. These switches are suitable for you to configure ACL, including 10GbE switch, 40GbE switch, 100GbE switch, etc. For more information, please read this news: FS.COM Collaborates with Cumulus Networks to Bring Open Networking Directly to Its 100,000+ Customers.

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Network OS Comparison: Open Source OS or Proprietary OS

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Open Source Switch: How Much Do You Know?

Usually, most enterprises employ closed switches in the data center. However, with the increasing demands for customized hardware and software of the switch, the open source switch starts drawing companies’ attention. Well, what is open source switch? How many kinds of open source switch do you know? This article will give a thorough introduction to it and make a comparison of open source switches.

What Is Open Source Switch?

The open source switch is the network switch that runs an open network operating system (NOS). Its hardware and software are separate entities and can be changed independently. Therefore, the same hardware can support different operating systems or the same operating system can work on multiple hardware configurations. This allows vendors to customize or rebrand their open source switches by adding their own software. Moreover, bare metal switch, white box switch, and brite box switch are three kinds of commonly used open source switches in the market.

Open source switch

Figure 1:Open source switch

Open Source Switches Comparison

Are there any differences among bare metal switch, white box switch, and brite box switch? Some are not clear about these open source switches. The following will make a comparison of them.

Bare Metal Switch vs. White Box Switch

The bare metal switch is from original design manufacturers (ODMs) such as Alpha Networks or Accton. These companies design and manufacture products for many of the mainstream switch vendors. However, warranties offered by ODMs are just hardware based and very basic. That’s to say, the bare metal switch has no label, no operating system, and at a low cost. What’s more, it comes with a boot loader called the Open Network Install Environment (ONIE). Based on ONIE, consumers can load NOS onto the switch. And there are multiple operating systems, including Cumulus Linux, Big Switch Light, Pica8 Pic, etc.

The white box switch is the Gigabit Ethernet switch without a label. Basically, it comes with three types. The first type is the one whose OS and the hardware are completely separated. This type is just like a bare metal device. The second type of white box switches may be brought from the vendor who pays more attention to the service of hardware and OS. The third type has hardware and installed OS just like the branded switch, but it can be labeled with the brand of buyer’s company or with no brand labeled.

All in all, a white box switch differs from a bare metal switch in that it comes with an operating system installed.

White Box Switch vs. Brite Box Switches

Just as the bare metal switch, brite box switch is often used interchangeably with white box switch. White box switch is able to use generic, off-the-shelf switching, and routing hardware. Brite box switch is made by an ODM and is often the same switch offered by the ODMs as bare metal. However, it sports a front bezel with a brand name like HP or Dell that it supports a brand name of any reputed IT vendors. All in all, the brite box switch refers to the branded white box switch.

Bare Metal Switch vs. White Box Switch vs. Brite Box Switches: Which Is the Best?

As mentioned above, bare metal switch, brite box switch, and white box switch are all open source switch. They share some similarities, but they still have some differences. Bare metal switch mainly matters to commercial software providers. Brite box switch has the brand. Actually, white box switch has more advantages than bare metal switch and brite box switch. The white box switch is cost-effective and flexible, and its reliability is equivalent to the brand-name switch. More and more enterprises choose white box switch to customize the devices to their need.

Conclusion

The open source switch is more and more important in the networking industry. When choosing open source switches such as bare metal switch, white box switch, and brite box switch, you’d better consider your needs. Any requirements for open source switch, including 1G switch, 10G switch or 40G switch, please contact FS.COM.

Related Article: Whitebox Switch vs Brite-box Switch: Who Is the Winner?

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What Is the Right Router to Switch Connection Diagram?

There are some different ways to set up a network connection, but the most reliable way is to use both the router and the switch. Well, do you know the right router to switch connection diagram? This article will give a clear explanation for the router, the switch and the router to switch connection diagram.

What Are Switch & Router?

The network switch is commonly applied in campus environments, business and other large networks. Usually, it works at the data link layer (layer 2) or the network layer (layer 3) of the OSI (Open Systems Interconnection) model. Therefore, it can support multiple packet protocols. As a multi-port network bridge, the network switch provides various ports for subnets to connect computers, cameras, printers, etc. Through these ports, the data packets can be sent and received between LAN segments.

Router, sometimes called Gateway, is a hardware device usually applied in home and small business networks. Based on layer 3 information of the OSI model, router functions to route packets or traffic by using IP address. This enables the network to go across different protocols.

Network Switch vs Router

Network switch and router both are broadly deployed in network data transmission but they definitely have some differences. Generally, they have three key differences. Firstly, routers typically use software to route. While network switches route packets on ASCI (Application Specific Integrated Circuit) hardware. Another difference is that network switches route packets faster than routers. In addition, based on IP addresses, routers can support numerous different WAN technologies. However, network switches lack some QoS (Quality of Service) features. Actually, the best way to set up a network connection is to use a router and switch in combination.

How to Connect a Switch to a Router?

Conventionally, the router is the first thing you will set up in the LAN. Since the Fiber Optic Service (FiOS) is now widely provided by many Internet providers, a modem should be connected after the router. It turns the digital signal to electrical signals, then these signals can be transmitted over Ethernet cables. Usually, a network firewall is between the internal network and the router so that all flows in and out can be filtered. However, most of the routers include the firewall feature. So there is no need for you to buy a firewall additionally. Then the switch follows. This is the general router to switch connection diagram and the following are the detailed steps to connect a switch to a router.

Router to switch connection diagram

Figure 1: Router to switch connection diagram

1. Unplug the power supplies of all the devices you will connect, including cable modem, wireless router, and the switch. And unplug any Ethernet cables that are plugged into any of them.
2. Connect telephone wire with the modem and connect an Ethernet cable to the port on the back of the modem.
3. Connect the other end of Ethernet cable connected with modem into WAN port of the router.
4. Connect an Ethernet cable to one of the numbered ports on the switch, then connect the other end to a wired device such as a computer or a gaming console.
5. Connect another Ethernet cable to one of the ports on the back of the switch and connect the other end to the port at the back of the modem.
6.Power on the router, modem, Ethernet switch, and the devices connected to the switch. After several minutes, the connection is ready to go.

Summary

After reading this article, you may clear about the right router to switch connection diagram and the proper way to connect them step by step. For suitable switches with high-quality such as 1GB Ethernet switch, 10GB Ethernet switch, 40GB Ethernet switch, or 24-port switch, 48-Port Gigabit switch and so on, FS will be your ideal choice.

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Transceiver Module Temperature: How Much Do You Know?

Transceiver module temperature has an important effect on the function of communication system. If the temperature of transceiver module is over its given range, it will cause transmission delays, drastically reduced output and network partitions. This article will give a clear explanation for the transceiver module temperature.

Transceiver module

Figure 1: Transceiver modules

What Is Transceiver Module Temperature?

The transceiver module temperature determines the available temperature of transceiver modules. According to different types and brands, transceiver modules may have different temperature ranges. For example, the temperature range of optical transceiver is larger than copper module, and the temperature range of SFP module is smaller than SFP+ module such as 1000BASE-SX SFP is from 0 to 70°C while 10Gbase-SR is from -40°C to 85°C. Conventionally, the transceiver module temperature mainly includes three levels: commercial temperature range (COM: 0~70°C), extended temperature range (EXT: -20°C~85°C), and industrial temperature range (IND: -40°C~85°C).

Transceiver module temperature

Figure 2:Transceiver module temperature

Why Suitable Temperature Is Needed on Transceiver Module?

Each transceiver module has its operating temperature range. If the temperature is too high or too low, the transceiver module will not work normally.

If the operating temperature is too high, its optical power will become larger and the receiving signal will be incorrect, which leads to the disordered operation of the transceiver module. Or even worse, the transceiver module would be burned. Facing this problem, you can add a temperature control system for real-time monitoring and compensation. It can ensure the transceiver module extinction ratio and stable luminous power, which helps the optical system work normally.

If the operating temperature is too low, the function of the transceiver module also will be unstable. Usually, the temperature of the transceiver module will not be too low as long as the transceiver is not put in the environment with a temperature below 0°C.

What Can Affect the Transceiver Module Temperature?

When a transceiver module is being used, the power consumption and case surface will affect its temperature. Except these, there are mainly three aspects that affect the transceiver module temperature.

  • Poor quality – The transceiver module with poor quality has unstable function and poor heat dissipation. As a result, the abnormal temperature of the transceiver module will happen very frequently. While, if you use the transceiver module with better quality and workmanship, the temperature anomaly and unnecessary discard will be reduced.
  • Harsh application environment – Transceiver modules are commonly used in the computer room, home networks, and data center. If they are applied in other harsh environments such as oil, deserts, mountains and so on, the temperature of these transceiver modules will be changed by the ambient environment. Then their optical power and optical sensitivity will be damaged.
  • Using second-hand transceiver modules – As mentioned above, the temperature of a new transceiver module is at 0-70°C. While the temperature range of the second-hand transceiver module is smaller than the new one. Because some functions of the second-hand one have degenerated.

Conclusion

Transceiver module temperature stability is an important factor to ensure module work normally. FS.COM provides comprehensive transceiver modules which have a wide temperature range with a very high tolerance level, such as the compatible GLC-LH-SMD module covering commercial temperature from 0 to 70°C. All modules from FS are 100% tested and have a reliable quality. If you have any needs, welcome to visit FS.COM.

Related Article: SFP Module: What’s It and How to Choose It?

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Ethernet Switch vs Hub vs Splitter: What’s the Difference?

Ethernet switch, hub and splitter all are networking devices that are designed to connect computers, other network devices, or even other networks. However, each of them has its special merits and drawbacks. Then, what on earth are they and what’s the difference between them? In this article, we will explore Ethernet switch vs hub vs splitter.

Ethernet switch vs hub vs splitter

Figure 1: Ethernet switch vs hub vs splitter

Ethernet Switch vs Hub vs Splitter: What Are They?

Ethernet Switch

Usually, an Ethernet switch works at the data link layer (layer 2) or the network layer (layer 3) of the OSI (Open Systems Interconnection) model. Therefore, it can support multiple packet protocols. As a multi-port network bridge, the Ethernet switch provides various ports for subnets to connect computers, cameras, printers, etc. Through these ports, the data packets can be sent and received within a LAN.

Hub

A hub commonly operates at the physical layer or layer 1 of the OSI model. It consists of different ports used to connect segments of a LAN. When a data packet arrives at one port, it is copied to other ports that all packets can be seen by all segments of the LAN.

Splitter

The splitter is an integrated optical power distribution device. It is one of the commonly used passive optical devices. And it is used to split a light beam into two or more light beams and couple them to the branch distribution without external power.

Ethernet Switch vs Hub vs Splitter Comparison

There is a saying, hubs are yesterday news and splitters are basically unnecessary. An Ethernet switch is probably what you want. Is that true? Here we will make a comparison between them.

Ethernet Switch vs Hub

Ethernet switch and hub have similar roles in the network. To understand the difference between Ethernet switch and hub, we’d better get to know frames first. The frames act as a central connection that carries data. And these frames can be received, amplified and then transmitted on to the destination port. The main difference between Ethernet switch and hub is the way that frames are being sent.

Ethernet Switch vs Hub

Figure 2: Ethernet switch vs hub

The hub can not examine the data it receives or sends. Therefore, just as mentioned above, when a frame arrives at one port, other ports will copy the data to ensure the data can be delivered to its destination. With this feature, a hub can create more connection points, which extends the network. However, this may cause a lot of traffic. What’s more, the bandwidth of the hub needs to be shared with its ports, which slows down the network. So the hub is usually used for the small-sized home network.

Ethernet switch can keep the record of the MAC (Media Access Control) addresses of all the devices connected to it. Therefore, when a frame is received, a switch knows which port it will be sent to. Moreover, unlike the hub, the switch allocates the same and full bandwidth to each of its ports.

All in all, the Ethernet switch is regarded as a better choice than the hub. Instead of using the hub, you can use 8 port switch for small-sized family. And you also can use 1GB switch or other Ethernet switches with larger capacity for busy networks.

Ethernet Switch vs Splitter

As mentioned above, splitter plays an important role in the passive optical network. It means that the splitter doesn’t need power input to split a single Ethernet connection into two connections. However, it needs to be used in pairs. What’s more, the splitter is based on 100BASE-T standard, which deals with network traffic at the rate of 100Mbps. So is it not suitable for long transmission or large data center.

In terms of Ethernet switch, it usually needs a power input. So it can divide an Ethernet signal into multiple signals and these signals can operate simultaneously to achieve a fairly long distance. Besides, Ethernet switch is a high speed networking device with multiple ports. You can use one port to connect the switch to the router and the rest to connect other devices. As a result, different devices such as computers, video game consoles, and printers can be connected by the switch and still work fast in a system.

Ethernet Switch vs Splitter

Figure 3: Ethernet Switch vs Splitter

If you want to connect additional computers or a switch in the same room or nearby rooms, you can choose the splitter. While the Ethernet switch is more widely used in building, campus and so on.

Conclusion

As for Ethernet switch vs hub vs splitter, we know they are used for different purposes. The best Ethernet device is the one that suits your needs most. So you can choose to buy switch, hub or splitter according to your demands. If you want to know more information such as network solution, 8 port switch price or 24 port switch price, welcome to visit FS.COM.

Related Article: What Is a Fiber Optic Splitter?

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