File server on a free OS

Many users periodically encounter one or another network problems. The situations here may be different. For example, the quality of communication may deteriorate and some servers may become unavailable. Such failures can be critical for users of online services, for example, traders trading in the stock market, players in network games etc. It happens that after changing some settings on the computer or changing the provider, it is not possible to access the network at all, and when setting up home network, for example, it turns out that only one of the computers has access to the Internet, etc. In many such cases it is necessary to carry out diagnostics network connection and check the performance of a particular remote node.

⇡ Built-in Windows tools - Ping and Tracert utilities

OS Windows has several utilities for diagnosing network status, but the most commonly used are Ping and Tracert. The Ping program sends a request to the specified network node and records the time between sending the request and receiving the response (RTT, from the English Round Trip Time), in other words, the utility allows you to determine the response time of the server of interest. It is clear that the smaller it is, the faster the data exchange with this server is. The Tracert program sends a test packet to the specified host, displaying information about all intermediate routers through which the packet passed on the way to the requested host, as well as the minimum, maximum and average response time of each of them. This allows you to estimate how long the packet has traveled and in which section the greatest delays associated with data transmission occur. What do the results produced by the Ping and Tracert utilities mean? For example, the lack of response from the remote server may indicate that it is currently unavailable, or that the server administrator has blocked echo requests (while other server services may be working normally). If the response time (RTT) of remote servers is too long and does not depend on their location, most likely the quality of your connection leaves much to be desired and you should contact your provider. However, you can get some speed gains by setting up your Internet connection to maximum performance, for which it is better to use special optimizer utilities such as TweakMASTER, but this is a completely different topic. The route to the server of interest is too “long” (that is, large number intermediate routers on the way to connect to the server) often leads to slower communication with it. If this is critical, then it makes sense to try to look for options to reduce the length of the route. For example, in case game servers you can make a choice in favor of those that are as close as possible to the server of your Internet provider. If the utilities show that test packets do not pass further than your provider’s server, it is very likely that problems have arisen on its side, or maybe this is scheduled maintenance work. There are no tricks in using the Ping and Tracert utilities, but technically using them is not very convenient. To run a ping test or trace, you will have to open a command line window and enter a command, possibly with parameters that you either need to remember or refer to help each time. For example, to check the functionality of the www.site site, you will need to enter command line team ping www.site, and to find out the path of packets to a given node - the command tracert www.site. The results of these commands are presented below and are several lines of text. Note that you can also run the specified commands through the “Start” > “Run” menu, but in this case the program window will automatically close immediately after its completion and all results will be lost.

It is much more convenient to use specialized utilities that can trace the “travel” of packets over the network and report it using the server’s IP address additional information. Such utilities can be very useful for quick analysis and source identification network problems. We will focus on using such utilities in this article.

⇡ Diagnostic services

You can also use the "IP lookup" tool to find out some details about the IP address of interest, including the host name, geographical coordinates and location on the world map. Why is this necessary? Well, for example, to reach the source of an intrusion into your system, if you have detected one. Using the "Visual Trace Route Tool" function on the Yougetsignal.com service, you can also conduct a trace by simply entering the server URL or its IP address and clicking on the "Host Trace" button. As a result, the service will display the path of the packets on a world map, as well as in the form of a list of intermediate servers indicating the total number of transitions and the belonging of each of them to a specific country. By activating the "Network Location Tool" function, you can find out the geographical location of any server by its IP address. And using the "WHOIS lookup Tool" function you can get information about the server from information service WHOIS.

The Whois service will help you establish the response time of the server of interest (the “Ping” function), determine the path of the request to the server and find out how many and which intermediate Internet servers, routers and other devices are involved in sending data to the server and back (Tracert).

In addition, using the "IP Lookup" function, you can find out its IP address by the host name (or vice versa), and the "Whois" function will tell you whether the specified domain is free or busy. If a domain is taken, you can identify its owner and how to contact him (if, for example, you want to buy this domain name).

Server maintenance is a whole range of measures to ensure stable operation computer equipment, requiring specialized knowledge and sufficient experience. After all, not only the operation of specific computer equipment, but also the functioning of an entire company may depend on the level of qualifications of specialists in this profile.

Maintenance of servers and related equipment - important condition high-quality and stable work information systems. The safety of information and its protection from unauthorized access depends on it.

Full comprehensive server maintenance includes many operations. First of all, it involves the actual installation, configuration and maintenance of servers and server equipment.

Before installing server equipment, all the requirements for the equipment are seriously analyzed. And on their basis, exactly the type of equipment and system configuration that is appropriate in this particular case is selected.

Then the server equipment is installed and configured. Then it is connected and started. The necessary software is installed, tested, configured and begins to be used.

When all the necessary operations have been completed, constant mode server maintenance is carried out:

– continuous monitoring of the state of the system and its individual services

– its performance is supported

– the main and backup power supplies are checked

– Batteries must be checked and replaced frequently

– operation of input/output devices, which include a keyboard, mouse, monitor, switches for connecting them to system units, wires and connectors

– Cables should be regularly inspected for external damage.

– the heating level of the fuel-generating components of the equipment is also checked

– and the operation of ventilation and air conditioning systems - in in this case It is essential that there is no interference with the cooling of the equipment

Server maintenance operations also include hardware repairs. changes and replacement of components if the load on the server increases.

It also checks that the server is configured correctly and ensures that it works well by frequently checking software and hardware components. Particular attention is paid to managing access rights to classified information and periodic backups. In this regard, there is a constant check of the performance and wear of equipment backup.

One of the goals of the server maintenance work performed is to protect data from external dangers, for example, from unauthorized access and malware, called viruses, and from internal ones, which include malfunctions software.

In addition to the other procedures mentioned above, when performing server maintenance that are mandatory, it is also important to periodically clean the servers.

Over time, dirt and dust accumulate in the server case and power supplies, which is extremely important to get rid of in a timely manner. Otherwise, you may encounter an extremely unpleasant situation - system overheating. Also an extremely important procedure is to inspect the operating capacity of the fans. If you do not carry out the above procedures in a timely manner, as a result, the operation of the server equipment may significantly slow down or even become unusable. To prevent this problem from occurring, you should periodically check and clean the server.

In addition to other procedures, the list of services provided by server maintenance companies also includes job prices:

– diagnostics and audit of equipment

It is unlikely that it will be a secret for anyone that after the expiration of the Over time, systems begin to work slower, which becomes noticeable without specific time measurements. The objectives of the audit include increasing system performance and reconfiguring and upgrading server equipment. Constant monitoring helps to diagnose problems in the early stages. Thanks to this, various critical situations do not arise during the operation of the system.

Server maintenance operations include updating the OS (operating systems), programs and control panel.

In this regard, the server maintenance specialist periodically checks the availability of latest updates BY. An important area of ​​work for a server maintenance specialist is:

– support and administration of corporate mail

Thanks to server maintenance, it becomes possible to check license expiration dates. To determine how well the server will work, a specialist checks its speed, integrity, etc. the average and peak load placed on it, the system of duplication, redundancy, etc.

Server maintenance includes:

– optimization of Internet traffic, which involves filtering it

– Checking the total external traffic, it is found out which ports are open, the mass storage devices are filled

There is also such a type of server maintenance as remote admin instrumentation.

It includes account management and related network resources. This type work involves servicing specialized server roles, which include ActiveDirectory, ExchangeServer, ISA, SQL and others.

Remote work involves a significant modification of the work, making server maintenance work convenient for both the Customer and the Contractor, because server maintenance is carried out online. Remote administration involves analyzing system logs and identifying elements and software components that require configuration. As with ordinary work, backup procedures are controlled. This includes, among other things, timely update operating system.

As a result of server maintenance, it becomes possible to establish uninterrupted operation of the enterprise, and maintenance costs are reduced to a minimum through the use of IT outsourcing services. These procedures ensure safety, protection and, at the same time, accessibility important information for certain categories of users.

Maintaining computers and servers is an important task for any enterprise, especially large ones. Today, the activities of any company directly depend on computers. Their condition determines the speed of work and its quality. Setting up and maintaining servers is a whole chain practical actions. They can be committed both by employees of the enterprise, which is not always profitable, and by special companies.

Server Maintenance

Information security and permanent job systems directly require server maintenance. Maintaining a server requires many steps, such as installation and Before installing the equipment, you need to check it. Afterwards, the server equipment is installed and launched. It is also important to install and configure the software. Additional safety equipment can also be installed. It is important to take maintenance seriously, otherwise it may result in loss of information.

Subsequent operations

After completing all operations and starting the system, it is necessary to constantly monitor the system parameters and make sure that the batteries, cables, and wires are in good condition. The heating of system equipment, which depends on the proper operation of air conditioners and fans, must also be controlled; it is also important to ensure uninterrupted power supply. A constant supply of electricity is one of the most important points. Therefore, for serious work, it is better to immediately install so-called uninterruptible power supplies, thanks to which system equipment will be able to work even if there is no electricity.

Server subscription service

Subscriber service for servers is nothing more than improving the company’s performance by assigning responsibilities for server repair, configuration and service to professionals. A server is a computer equipped with peripherals that allow it to work continuously twenty-four hours a day and process huge amounts of information. The operation of portals and websites on the Internet depends on the server.

Using the server and the special software installed on it, it is possible to access the Internet, safe storage important and necessary information and even restoration of lost information. It is important to know: the larger the company, the more powerful the server should be, since a large company has many employees. This means that in order to maintain the operation of this equipment it is necessary to provide this work professionals in their field. Often, the solution to minor problems is left to private employees, but in more serious cases, they still provide the repair of server equipment to an IT company specializing in this area. Good server maintenance will avoid the loss of important information and system failures.

Remote administration

Let's figure out what remote administration is.

This is one of the types of server services that involves system management and accounts at a distance. Remote work creates a certain comfort for users. Remote management involves reviewing system logs and troubleshooting for subsequent configuration. Backup control is carried out. Also included is the ability to change or update the operating system.

After server maintenance, there is an opportunity to reduce costs due to the use of IT services. Also, thanks to the use of these services, it is possible to achieve uninterrupted operation of the server, and therefore the enterprise. This will ensure the security of stored information and the ability to obtain it for a certain class of users.

Terminal servers

On at the moment many economic entities can afford to have service complexes, but this entails large costs: firstly, for assembly, configuration, installation and technical service, and secondly, for the maintenance of this complex, since it consumes large amounts of electricity .

Remote server maintenance

Remote server maintenance is widely used in the activities of any company. Today there are many organizations that can maintain computers and servers remotely. In such situations, a unique type of device is used to ensure communication between remote nodes. For this, a remote access server that can process data different computers, connect to the network. This technology is widely used, as it makes the activities of all kinds of companies easier and more comfortable.

Remote control and remote nodes are all types of remote access servers. Remote node services have the meaning of connecting users to each other. controls, in turn, transfer data and can also open various files on computers, creating an image on the screen of another computer of this file. They work with the Windows operating system.

Domain controller server maintenance

Improving any IT infrastructure is nothing more than customizing the operating system. For example, you can limit access to the Internet - this will greatly improve the productivity of employees. If you want to reduce Internet traffic costs, you need to install an Internet gateway and proxy server. May require full control email correspondence at the enterprise. This is possible when installing letters. There will no longer be a need for the services of hosting providers. If the enterprise needs to organize collaboration with large amounts of information, it is best to configure a database server.

Server maintenance is essential to ensure that all equipment does not fail, which is extremely important in any enterprise. It also significantly extends the service life installed equipment and prevents sudden failure. You can quickly respond to system errors and eliminate them effectively even in remote access. Therefore, it is absolutely not necessary to keep a highly paid employee on staff. It is much more profitable to entrust server maintenance to a company working in this profile.

Updated: 02/10/2017 Published: 02/04/2017

Server maintenance is a set of measures aimed at ensuring trouble-free operation services that work on this server, as well as increasing the service life of server equipment. To maintain uninterrupted operation or minimize failures, it is necessary to perform work in at least two directions - maintaining the functionality of the hardware and error-free operation of the software.

1. Equipment maintenance

1. Power supply. You need to make sure there is a source uninterruptible power supply(UPS) and a sufficient charge level of its battery. It is desirable that the UPS can send a signal to shut down the server if there is very little charge left.
2. Dust. From time to time, it is necessary to clean the server from accumulated dust. To do this, it is recommended to use cans of compressed air. Particular attention should be paid to coolers.
3. Indication. Visually inspect the server - if any of the hardware components are malfunctioning, you can see a burning red light. Most often hard drives fail. It is necessary to notice the problem in time in order to have time to replace components and avoid data loss.
4. Server room. The room where the server equipment is located should have a low air temperature - monitor the operation of the air conditioning system. The room must be clean.

2. Software maintenance

1. Installing updates. They contain critical bug fixes as well as new features. That's right, install updates on a test server first to check their correctness. Otherwise, you can harm the system.
2. Security check. Includes searching for system security updates and installing them. As well as maintaining the relevance of anti-virus databases and running virus scans (preferably one-time antivirus, for example CureIt).
3. Reading system logs (logs). Most best way fix the problem - prevent it from happening. Using logs, you can track all errors and warnings that occur in the system and prevent serious consequences. It is necessary to pay special attention to system logs and messages from critical applications.
4. Perform optimization. During server maintenance, you should review performance counters to look for processes that are overloading the system. It is also necessary to clean the system of temporary files, perform disk defragmentation and its logical check.
5. Examination hard conditions disks. Disk drives, for two reasons, are one of the most important objects of verification - firstly, they contain the most valuable data - data, and secondly, they often fail. It is necessary to check the condition of the disk surface using specialized utilities, such as HD Tune.

Windows and Linux - what is the difference in support

As a rule, there are no fundamental differences in the maintenance of servers based on Windows and Linux. Only the commands, tools and their appearance. IN Windows more We work with the mouse, in Linux - with the keyboard.

Here's a short list of differences to look out for:

• Linux needs to be rebooted less frequently after installing updates. This is important to take into account for Windows and update the system during non-working hours.
• Systems on Linux based less susceptible virus attacks and hacking. However, you shouldn’t relax - viruses still exist and it’s worth taking precautions for this. Thus, there is no need to exclude anti-virus scanning from the regulations - just to Windows systems this needs to be done more often.

3. How to accept a server for service

Regardless of whether the server was transferred to another specialist or you are seeing it for the first time, the actions should be as follows:

1. To access the system, we obtain a login and password and change the latter. It would also be a good idea to change the passwords for all accounts with administrator privileges. If there is no authorization data, you need to reset your password.
2. We perform an audit of previously installed software. If software for remote control, delete or change authentication data.
3. We check the task scheduler (on Windows) and cron (on UNIX-based systems). We study what exactly is running and disable everything unnecessary and contrary to safety.
4. We carry out maintenance activities for hardware and software parts described in these instructions above (1st, 2nd points).

4. Monitoring and backup

Two integral components of a professional approach to server maintenance.

Monitoring

First of all, it is necessary to monitor the network availability of the equipment. If monitoring allows, it is also worth checking service statuses, response codes to requests, and the availability of free disk space.

Backup

As part of periodic server maintenance, it is important to check that backup copies, but what’s more important is the ability to recover data from them.

5. Drawing up regulations

For professional maintenance of server equipment, it is necessary to stipulate in advance the procedure for carrying out work, in other words, draw up regulations. It should include a list of operations performed and the frequency of their execution. Also, the document can specify the speed of response to emerging problems.

Example of regulations for server maintenance

6. Remote service

With this support option, it will not be possible to complete the tasks of point 1. In this case, there are three options:

1. The customer maintains the equipment using his own resources.
2. The contractor organizes business trips.
3. The contractor finds a contractor to perform equipment maintenance work.

Lecture 13 Network diagnostics

Lecture 13

Topic: Network diagnostics

A. Network administrators who shape the network environment (the vast minority).

b. Network users who are forced to master this environment and live in it.

The second category, due to its numerical superiority, is capable of asking so many questions that the first, even being equally numerous, could not answer. The questions can be simple, for example: “Why isn’t email working?” (although it is known that the entire power supply was cut off on the second day for non-payment computer center). There are also complex ones: “How to reduce response delay if the channel is overloaded?”

Number computer networks is increasing exponentially, the number of large (>10 PCs) and multi-protocol networks (802.11, 802.16, 802.17, etc.) is growing. As the network grows, its maintenance and diagnostics become more complicated, which is what the administrator faces at the first failure. It is most difficult to diagnose multi-segment networks, where PCs are scattered across a large number of premises, far apart from each other. For this reason, the network administrator should begin to study the features of his network already at the phase of its formation and prepare himself and the network for future repairs.

If an emergency situation occurs, the administrator must be able to answer a number of questions:

There is a hardware or software problem;

The failure is caused by program corruption, incorrect configuration choices, or operator error.

Network diagnostics is the process of obtaining and processing information about the state of the network.

Documenting the network

You need to start with comprehensive documentation of the hardware and software of the network. The administrator should always have at hand a network diagram that corresponds to the real situation at the moment, and detailed description software configuration indicating all parameters (physical and IP addresses of all interfaces, masks, names of PCs, routers, values ​​of MTU, MSS, TTL and other system variables, typical values ​​of RTT and other network parameters measured in different modes.).

Within local network Troubleshooting is possible by temporarily dividing it into parts. As the network becomes more integrated into the Internet, such simple measures become insufficient or unacceptable. But you should not neglect such simple means as checking that the network cable is not broken or shorted.

It should be remembered that network diagnostics are the basis of network security. Only an administrator who knows everything about what is happening on the network can be sure of its security.

In the lecture it will be assumed that the network is on physical level uses the Ethernet standard, and for internetwork communication the TCP/IP protocol (Internet). This list does not exhaust the variety of network environments, but many techniques and software diagnostic tools can be successfully used in other cases. Most of the programs under consideration work in the UNIX environment, but there are analogues for other operating systems.

The source of diagnostic information can be a computer, its processor, network interface, operating system installed on the machine, network switches, routers, etc.

When moving to transmission standards of 1 and especially 10 Gbit/s, additional problems arise. Processing such streams for diagnostic purposes can significantly slow down the machine. Similar problems arise when building IPS/IDS systems, as well as anti-virus programs. However, this problem is also becoming severe due to the fantastic growth in the number of signatures (millions) of attacks and viruses. One way to solve the problem is to use hardware, as well as organize several processing threads, which is quite realistic for machines with several processors.

Diagnostic software

There are many publicly available specialized diagnostic software products on the Internet: Etherfind, Tcpdump, netwatch, snmpman, netguard, ws_watch.

Such tools are also included in the delivery of most standard network packages for MS-DOS, UNIX, Windows NT, VMS and others: ping, tracetoute, netstat, arp, snmpi, dig (venera.isi.edu /pub), hosts, nslookup, ifconfig, ripquery. The diagnostic programs listed above are essential tools for debugging programs that send and receive packets.

OS diagnostic commands

Table 1.

Team name Purpose

arp Displays or modifies the ARP (IP to MAC address translation) protocol table

chnamsv Used to change the configuration of the name service on the computer (for TCP/IP)

chprtsv Changes the print service configuration on a computer client or server

gettable Gets computer tables in NIC format

hostent Directly manipulates computer address correspondence records in the system configuration database

hostid Sets or displays the identifier of this computer

hostname Sets or displays the name of this computer

htable Converts computer files into a format used by network library programs

ifconfig Configures or displays options network interfaces Computer (for TCP/IP protocols)

ipreport Generates a packet route report based on the specified route file

iptrace Provides packet route tracking at the interface level for Internet protocols

lsnamsv Displays DNS database information

lsprtsv Displays information from the network print service database

mkhost Creates a PC table file

mknamsv Configures the PC client name service (for TCP/IP)

mktcpip Sets the required values ​​for running TCP/IP on the computer

namerslv Directly manipulates name server records for a local DNS program in the system configuration database

netstat Displays network status

no Configures network options

rmnamsv Removes the TCP/IP name service from the host

rmprtsv Removes the print service on a client or server machine

route Used for manual manipulation of route tables

ruptime Displays the status of each computer on the network

ruser Directly manipulates records in three separate system databases that regulate external computer access to programs

securetcpip Enables network security

setclock Sets the time and date for a computer on the network

slattach Connects serial channels as network interfaces

timedc Sends information about the timed daemon

trpt Performs protocol implementation tracking for TCP sockets

In order to diagnose a network situation, it is necessary to understand the interaction of its various parts within the framework of the TCP/IP protocols and have some understanding of the operation of Ethernet.

Networks that follow Internet guidelines have local server names (DNS, RFC-1912, -1886, -1713, -1706, -1611-12, -1536-37, -1183, -1101, -1034-35; numbers printed in bold correspond to document codes containing descriptions standards), which serves to convert the symbolic name of a network object into its IP address. Typically this machine is based on UNIX OS.

The DNS server maintains a corresponding database that stores a lot of other useful information. Many PCs have SNMP residents (RFC-1901-7, -1446-5, -1418-20, -1353, -1270, -1157, -1098) serving the management MIB database (RFC-1792, -1748-49 , -1743, -1697, -1573, -1565-66, -1513-14, -1230, -1227, -1212-13), the contents of which will also help you learn a lot of interesting things about the state of your network. The Internet ideology itself presupposes rich diagnostics (ICMP protocol, RFC-1256, 1885, -1788, -792).

Using the ICMP protocol

The ICMP protocol is used in the most popular diagnostic program, ping (included in almost all network packages). A possible form of calling this program is:

ping<имя или адрес ЭВМ или другого объекта>[package size] [number of parcels]

In various implementations, the ping program has many different options that allow you to measure statistical characteristics of the link (for example, loss), determine the delay on the link (RTT), display the packets sent and the responses received, and determine the route to the point of interest. Ping is used to determine service provider availability, etc.

Below is an example of using the tracetoute command, which is largely equivalent to ping (but based directly on IP using the appropriate options):

traceroute kirk.Bond.edu.au

The traceroute program sends three packets with increasing TTL values; if a response to the packet is not received, the * character is printed. Long delays(RTT) in the above example are determined by satellite communication channels (signal propagation time to the satellite!).

In order to properly respond to emergency situations, you need to have a good understanding of how the network should work under normal conditions. To do this, you need to study the network, its topology, external connections, software configuration of central servers and peripheral PCs. It should be borne in mind that changing the configuration is usually the privilege of the system administrator and in any doubtful cases you should contact him. Unskilled actions when reconfiguring a system can have catastrophic consequences.

Using DNS for diagnostic purposes

As noted above, one of the most important parts of any Internet node is the name server (DNS). The DNS server configuration is determined by three files: named.boot, named.ca and named.local. Zone information is contained in the named.rev file, and local domain information is contained in the named.hosts file. Debugging, monitoring and diagnostics of the DNS server is carried out using the nslookup (or dig) programs.

The DNS server is very important object node, the speed of servicing requests and the reliability of the system as a whole depend on it. It is for this reason that, in addition to the main one, any node has several secondary DNS servers.

The ifconfig program is used to monitor the status of network interfaces, configure and test them. This command assigns an IP address, subnet mask, and broadcast address to the interface.

Application of NETSTAT

One of the most informative commands is netstat (for a comprehensive description of options and methods of application, I refer you to the documentation for your network software).

This command can give you information about the state of the interfaces on the PC where it is executed: netstat -i

IN lately Several comprehensive (publicly available) diagnostic packages have appeared (NetWatch, WS_watch, SNMPMAN, Netguard, etc.). Some of these packages allow you to build a graphical model of the network under test, highlighting working computers in color or using a variation of pictures. Programs that use the SNMP protocol check the availability of the SNMP daemon through a special request, determine the operability of the computer using the ICMP protocol, and then display variables and data arrays from the MIB control database (if this database has a public access level). This can be done automatically or at the request of the operator. The SNMP protocol allows you to monitor variations in the load of individual network segments with UDP, TCP, ICMP, etc. packets, recording the number of errors for each of the active interfaces. To solve this problem, you can use an appropriate program that regularly queries the MIB of the computers you are interested in, and the resulting numbers are entered into the appropriate data bank. If an emergency occurs, the network administrator can view variations in flows in network segments and identify the time and cause of the system failure. Similar data can be obtained using a program that switches the Ethernet interface to the mode of receiving all packets (mode=6). Such a program allows receiving data on all types of packets circulating in a given cable segment.

Of particular interest may be the ttcp diagnostic program, which allows you to measure some characteristics of TCP or UDP exchanges between two nodes.

When networks move to the gigabit speed range, in particular to 10 Gbit/s, difficulties arise in monitoring the state of the network.