Networks – Page 2

Why service networking restart or /etc/init.d/networking restart does not work

For example, take the server with the operating system Ubuntu Server 14.04, in which let’s say we changed the network settings when executing the commands:

Solution «TX driver issue detected, PF reset issued»

Once on one high-load access server with about 5 Gb/s traffic in /var/log/syslog, errors began to appear frequently:

Difference between MASQUERADE and SNAT

In this article I will briefly describe the difference between MASQUERADE and SNAT.

MASQUERADE. Less fast routing than SNAT with mass requests, since for each new connection an IP address on the external network interface (WAN) is determined. Great for home use routers and when changing the IP address on the WAN interface.
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PPS Viewer Script (Packets Per Second)

The script every second displays the number of incoming and outgoing packets per second on the specified network interface.
Place the contents of the script into a file, for example, pps.sh and execute by specifying the name of the network interface (you can stop the execution of the script with CTRL+C):

Installing and using ipset

ipset – a tool consisting of a kernel module, libraries and utility, allowing you to organize a list of networks, IP or MAC addresses, etc., which is very convenient to use for example with IPTables.
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What to do if “Network Discovery” does not turn on in Windows

Once I noticed on one of the computers that nothing was displayed in the network environment, and after selecting “Enable network discovery” in “Control Panel \ Network and Internet \ Network and Sharing Center \ Advanced Sharing Options”, the choice was still on “Disable network discovery”.
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How to view information about the network adapter in Linux

I will give examples of commands for viewing information about a network adapter in Linux.

View network interfaces and assigned IP addresses:

ifconfig
ifconfig -a
ifconfig -a | grep ens2f0
ip link show

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Speed limit on network interface using TC

I will give an example of a speed limit of up to 3.3 Gb/s on a network interface on Ubuntu Server 16.04:

/sbin/tc qdisc del dev ens2f0 parent ffff:
/sbin/tc qdisc add dev ens2f0 handle ffff: ingress
/sbin/tc filter add dev ens2f0 parent ffff: protocol ip prio 50 u32 match ip dst 0.0.0.0/0 police rate 3300mbit burst 330k mtu 30000 drop flowid 1:0

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nload – monitoring network interface bandwidth

nload – network interface bandwidth monitoring tool with graphical display in the terminal.

Installing nload on Linux Ubuntu/Debian:

sudo apt-get install nload

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Creating dummy interfaces on Linux

I will give an example of creating dummy interfaces in Linux.
On the test I use Ubuntu Server 16.04.

The first thing you need to load the module “dummy”, you can also add the option “numdummies = 2” to immediately create two dummyX interfaces:
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