How to Change MTU Value on Mac?

To set the best MTU value and optimize Internet speed, please perform the following steps: 1 Open “Terminal“   2 Type the command below and hit enter. ping –c 3 –D –s 1500 google.com   If the reply you get is “ping: sendto: Message too long”, then you have to try a lower MTU value. […]

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Preparing CentOS 7 for Mounting SMB Shares

A default CentOS 7 build will not be able to mount SMB\CIFS shares, unless you customized the install. We’ll need to install a package onto the server that allows it to understand the SMB protocol. Install the cifs-utils package from the default CentOS yum repository. yum install cifs-utils Next, we need an account on the […]

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Notion de VLAN

Configuration des vlans par port sur un switch Cisco. Les commandes suivantes ont été testées sur des switchs série 2950, 2960, 3750 et 6500. Rappel sur la notion de VLAN (Virtual Local Area Network) L’objectif d’une configuration de vlan est de permettre la configuration de réseaux différents sur un même switch. Il existe plusieurs façon […]

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tc: Adding simulated network latency to your Linux server

Have you ever said to yourself, « man I really need to slow down my internet »? Probably not very often, but recently I found myself in a dilemma where I needed to simulate 120ms of network latency in my test environment which consists of servers that are racked right next to each other. That is where […]

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CentOS Linux: Add Static Routing

I am a new CentOS Linux sysadmin. How can I add static route On CentOS Enterprise Linux server running on HP amd64 server? You can use any one of the following command line utility to add, delete, display, or manipulate the Linux kernel routing table on CentOS and friends: Tutorial details Difficulty Easy (rss) Root […]

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Linux TCP Tuning

To make persistent changes to the kernel settings described bellow, add the entries to the /etc/sysctl.conf file and then run « sysctl -p » to apply. Like all operating systems, the default maximum Linux TCP buffer sizes are way too small. I suggest changing them to the following settings: To increase TCP max buffer size setable using setsockopt(): 1 […]

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RedHat / Centos Disable IPv6 Networking

Our policy and network configuration does not requires IPv6 support in RHEL / CentOS / Fedora Linux. How do I prevent the kernel module from loading at boot time and disable IPv6 networking? You can easily prevent the kernel module from loading by updating the following two files: /etc/modprobe.conf – Kernel driver configuration file. /etc/sysconfig/network […]

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Disabled IPv6 on the OS X

Open Terminal and execute this command : Code: sudo networksetup -listallnetworkservices An asterisk (*) denotes that a network service is disabled. Service unknown Wi-Fi Bluetooth PAN sudo networksetup -setv6off Wi-Fi  

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Linux add ethtool duplex settings to a network card permanently

I have already written about how to find and change your network interface speed (NIC), duplex or auto negotiate settings on Linux using ehttool command line options. However, these settings are not permanent. If you reboot the system or if you just need to upgrade/downgrade your port speed, run the ehtool command once your port change by network administrator. (If you […]

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Linux change the speed and duplex settings of an Ethernet card

Q. How do I change the speed, duplex on for my Ethernet card? A. Under Linux use mii-tool or ethtool package which allows a Linux sys admin to modify/change and view the negotiated speed of network interface card (NIC) i.e. it is useful for forcing specific Ethernet speed and duplex settings. Depending on which type of Ethernet […]

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