Netstat linux �� ��������

11 примеров использования netstat

Команда netstat, входящая в стандартный набор сетевых инструментов UNIX, отображает различную network–related информацию, такую как сетевые подключения, статистику интерфейсов, таблицы маршрутизации, masquerade, multicast, и т.п.

В этой статье рассмотрим десять практических примеров использования команды netstat в Linux.

1. Список всех портов (как прослушиваемых, так и нет)

Перечислить все порты: netstat -a

Перечислить все TCP порты: netstat -at

Перечислить все UDP порты: netstat -au

2. Список сокетов, находящихся в состоянии LISTEN

Перечислить все прослушиваемые порты: netstat -l

Перечислить прослушиваемые TCP порты: netstat -lt

Перечислить прослушиваемые UDP порты: netstat -lu

Перечислить прослушиваемые UNIX сокеты: netstat -lx

3. Просмотр статистики для каждого протокола

Показать статистику всех портов: netstat -s

Показать статистику только TCP портов: netstat -st

Показать статистику только UDP портов: netstat -su

4. Отображение PID и имени процесса в выводе netstat

Опция netstat -p добавит «PID/Program Name» в вывод netstat, и может быть совмещена с любым другим набором опций. Это очень полезно при отладке, для определения того, какая программа работает на определённом порту.

5. Разрешение имён в выводе netstat

Когда вам не нужно резолвить имя хоста, имя порта, имя пользователя, используйте опцию netstat -n для вывода значений в цифровом формате. Команда покажет IP-адрес вместо хоста, номер порта вместо имени порта, UID вместо имени пользователя.

Это также ускорит вывод, так как netstat не станет выполнять ненужный поиск.

Для вывода цифровых значений только некоторых из этих пунктов, используйте следующие команды:

6. Вывод информации netstat непрерывно

Опция netstat -c будет выводить информацию непрерывно, в стиле top, обновляя экран каждые несколько секунд.

7. Неподдерживаемые системой семейства адресов

Опция netstat —verbose покажет подробный вывод, а в самом конце отобразит неподдерживаемые Address Family.

8. Маршрутизация ядра

Показать таблицу маршрутизации ядра: netstat -r

Примечание: Используйте netstat -rn для просмотра маршрута в цифровом формате без разрешения имён узлов.

9. Соответствие портов и процессов

Узнать, какой порт занимает определённая программа:

Выяснить, каким процессом используется определённый порт:

10. Сетевые интерфейсы

Показать список сетевых интерфейсов: netstat -i

Показать расширенную информацию об интерфейсах (аналогично ifconfig): netstat -ie

11. netstat -lnptux

Резюмируем вышеописанное и объединим ключи в одну полезную команду, которая покажет:

• -l все открытые порты (LISTEN)
• -t по протоколу TCP
• -u по протоколу UDP
• -x по протоколу UNIX Socket
• -n без резолва IP/имён
• -p но с названиями процессов и PID-ами

Примечание: Не все процессы могут быть идентифицированы последним ключом, чужие процессы показаны не будут. Вы должны иметь права root чтобы увидеть всё.

Источник

netstat Command Usage on Linux

Geekflare is supported by our audience. We may earn affiliate commissions from buying links on this site.

Learn what netstat command and some of the real-time examples are.

netstat (network statistics) is a command-line tool that displays network connections (both incoming and outgoing), routing tables, and a number of network interface statistics.

It is available on Linux, Unix-like, and Windows operating systems. netstat is powerful and can be a handy tool to troubleshoot network-related issues and verify connection statistics.

If you type netstat -help , you will get the following usage guidelines.

Let me show you some of the examples of the command. The following are tested on RHEL/CentOS, but I don’t see any reason not to work on another distro like Ubuntu.

Established Connection

If you are looking for all established connections from the server.

If you many established connections and interested in looking for one of the IPs, then you can use another grep.

Listening Connection

Let’s say you’ve started some service, and that is supposed to listen on a particular IP:Port, this would be handy to verify.

Or, you can use -l argument to show all the listening sockets.

Take advantage of grep to filter the results.

Port Number used by PID

You know your application started and aware of PID (Process Identifier) but not sure what’s the port number it’s using. Below example is for PID 3937

As you can see, port 80 is being used for PID 3937.

All Protocols Statistics

Having frequent disconnections due to packet discarded? -s argument will show you overall stats where you can pay attention to packets discarded messages.

Kernel routing information

Having a routing issue? or, connectivity is not working as expected due to connection is traveling through a different route?

Quickly check the routing table.

PID used by Port Number

Very handy to troubleshoot port conflict issue. Lets’s say you are trying to start Apache or Nginx server, which listens on port 80 but can’t because some other process already using port 80.

And, you can see the PID 3937 is using that port.

If you are using AIX, then

This will display the address of the Protocol Control Block in hexadecimal

Once you have hexadecimal, then can execute below to get wich process is holding a port number.

List of network interfaces

Having multiple ethernet interfaces? or not sure and want to find out?

Continuous Listening

An excellent option when troubleshooting services crash related issues. Let’s say an application is crashing randomly every few minutes. But, not sure when exactly. You can use -c argument which will continuously show the results.

When it stops updating, then you know its crashed.

Conclusion

netstat is one of the widely used commands by sysadmin and I hope the above examples give you an idea about what you can do with it. If you are looking to learn more about Linux administration, then check out this Udemy course.

Источник

20 Netstat Commands for Linux Network Management

netstat (network statistics) is a command line tool for monitoring network connections both incoming and outgoing as well as viewing routing tables, interface statistics etc.

netstat is available on all Unix-like Operating Systems and also available on Windows OS as well. It is very useful in terms of network troubleshooting and performance measurement. netstat is one of the most basic network service debugging tools, telling you what ports are open and whether any programs are listening on ports.

Update: The Linux netstat command is replaced by new ss command, which is capable of displaying more information about network connections and it is much faster than the older netstat command.

This tool is very important and much useful for Linux network administrators as well as system administrators to monitor and troubleshoot their network-related problems and determine network traffic performance. This article shows usages of netstat command with their examples which may be useful in daily operation.

You might also be interested in following article

1. Listing all the LISTENING Ports of TCP and UDP connections

Listing all ports (both TCP and UDP) using netstat -a option.

2. Listing TCP Ports connections

Listing only TCP (Transmission Control Protocol) port connections using netstat -at.

3. Listing UDP Ports connections

Listing only UDP (User Datagram Protocol ) port connections using netstat -au.

4. Listing all LISTENING Connections

Listing all active listening ports connections with netstat -l.

5. Listing all TCP Listening Ports

Listing all active listening TCP ports by using option netstat -lt.

6. Listing all UDP Listening Ports

Listing all active listening UDP ports by using option netstat -lu.

7. Listing all UNIX Listening Ports

Listing all active UNIX listening ports using netstat -lx.

8. Showing Statistics by Protocol

Displays statistics by protocol. By default, statistics are shown for the TCP, UDP, ICMP, and IP protocols. The -s parameter can be used to specify a set of protocols.

9. Showing Statistics by TCP Protocol

Showing statistics of only TCP protocol by using option netstat -st.

10. Showing Statistics by UDP Protocol

11. Displaying Service name with PID

Displaying service name with their PID number, using option netstat -tp will display “PID/Program Name”.

12. Displaying Promiscuous Mode

Displaying Promiscuous mode with -ac switch, netstat print the selected information or refresh screen every five second. Default screen refresh in every second.

13. Displaying Kernel IP routing

Display Kernel IP routing table with netstat and route command.

14. Showing Network Interface Transactions

Showing network interface packet transactions including both transferring and receiving packets with MTU size.

15. Showing Kernel Interface Table

Showing Kernel interface table, similar to ifconfig command.

16. Displaying IPv4 and IPv6 Information

Displays multicast group membership information for both IPv4 and IPv6.

17. Print Netstat Information Continuously

To get netstat information every few second, then use the following command, it will print netstat information continuously, say every few seconds.

18. Finding non supportive Address

Finding un-configured address families with some useful information.

19. Finding Listening Programs

Find out how many listening programs running on a port.

20. Displaying RAW Network Statistics

That’s it, If you are looking for more information and options about netstat command, refer netstat manual docs or use man netstat command to know all the information. If we’ve missed anything in the list, please inform us using our comment section below. So, we could keep updating this list based on your comments.

If You Appreciate What We Do Here On TecMint, You Should Consider:

TecMint is the fastest growing and most trusted community site for any kind of Linux Articles, Guides and Books on the web. Millions of people visit TecMint! to search or browse the thousands of published articles available FREELY to all.

If you like what you are reading, please consider buying us a coffee ( or 2 ) as a token of appreciation.

We are thankful for your never ending support.

Источник

How to Install netstat Command in Linux

Netstat – derived from the words network and statistics – is a command-line utility used by system administrators for analyzing network statistics. It displays a whole manner of statistics such as open ports and corresponding addresses on the host system, routing table, and masquerade connections.

In this article, we will walk you through how you can install the netstat command in different Linux distributions.

How to Install netstat Command in Linux

The package that contains netstat is called net-tools. On modern systems, the netstat utility comes pre-installed and there’s no need to install it.

On older systems, however, you are likely to bump into an error when you run the netstat command. Therefore, to install netstat on Linux distributions, run the command.

Once installed, run the command below to check the version of netstat installed.

How to Use netstat Command in Linux

You can invoke the netstat command on any of the Linux distributions to get different statistics on your network.

1. Viewing the Network Routing Table

You use the -r flag to show the network routing table to get something similar to the output below.

List Network Routing Table

The -n option forces netstat to print addresses separated by dots instead of using symbolic network names. The option is useful for avoiding address lookups over a network.

2. Display Network Interface Statistics

Use the -i flag to get an output of statistics of a network interface that is configured. The -a option prints all present interfaces in the kernel.

List Network Interface Statistics

3. Show Network Connections

The netstat command utility supports options that display active or passive sockets using the options -t , -n , and -a . The flags show RAW, UDP, TCP, or UNIX connection sockets. Adding the -a option, it will sow sockets ready for connection.

List Network Connections

4. Show Network Services

To list services, their current state, and their corresponding ports, run the command.

List Network Services

In this article, we shed light on how you can install netstat command and how it is used to checking a wide array of network statistics. It’s also important to point out that netstat has been deprecated and instead ss utility has taken its place in displaying more refined network statistics.

If You Appreciate What We Do Here On TecMint, You Should Consider:

TecMint is the fastest growing and most trusted community site for any kind of Linux Articles, Guides and Books on the web. Millions of people visit TecMint! to search or browse the thousands of published articles available FREELY to all.

If you like what you are reading, please consider buying us a coffee ( or 2 ) as a token of appreciation.

We are thankful for your never ending support.

Источник