How to Setup network on centos 7 and Configuring Web Proxy

Original Post: http://www.krizna.com/centos/setup-network-centos-7/

After installing Centos 7, You may not able to connect network in that machine. This will happen because Ethernet interfaces are not enabled by default.This guide will help you to setup network on centos 7 .
This guide contains network configuration steps both in GUI and command mode.

Setup network on centos 7

let’s start, Type “nmcli d” command in your terminal for quick identification of Ethernet cards installed in your machine.
Setup network on centos 7
Here we have 2 interfaces named “enp0s17” and “enp0s18” . it might be different in your case ( Eg: em1 or p4p1 ).

GUI Mode

Recommended for beginners
Step 1 » Type this command “nmtui” to open Network manager and press enter after choosing ” Edit a connection” ( Use TAB for choosing options ) .
Setup network on centos 7
Step 2 » Now you can see all network interfaces, choose one and click “Edit“.
Setup network on centos 7

» DHCP configuration

Step 3 » For DHCP,
1. Choose “Automatic” in IPv4 CONFIGURATION.
2. Choose Automatic Connect check box.
3. Press OK and quit Network manager.
Setup network on centos 7
Now Restart network service by typing below command.
systemctl restart network Now your server will get IP Address from DHCP .

» Static configuration

Step 4 » For manual IP address,
1. Choose “Manual” in IPv4 CONFIGURATION.
2. Add IP Address with Subnet , Gateway and DNS server ( Refer below image ).
3. Choose Automatic Connect check box.
4. Press OK and quit Network manager.
Setup network on centos 7
Now Restart network service by typing below command.
systemctl restart network That’s it, Interface will have static IP.

Command Mode

Step 1 » Network interface config files are located in /etc/sysconfig/network-scripts/ directory. Open ifcfg-enp0s17 file ( For interface enp0s17 ) and you can see the content like below.
[root@krizna ~]# vi /etc/sysconfig/network-scripts/ifcfg-enp0s17
TYPE=Ethernet
BOOTPROTO=none
DEFROUTE=yes
IPV4_FAILURE_FATAL=no
IPV6INIT=yes
IPV6_AUTOCONF=yes
IPV6_DEFROUTE=yes
IPV6_FAILURE_FATAL=no
NAME=enp0s17
UUID=7f1aff2d-b154-4436-9497-e3a4dedddcef
ONBOOT=no
HWADDR=00:0C:29:A1:B5:D6
PEERDNS=yes
PEERROUTES=yes
IPV6_PEERDNS=yes
IPV6_PEERROUTES=yes

» DHCP configuration

Step 2 » For DHCP
Find the below lines in config File.
BOOTPROTO=none
ONBOOT=no
and replace with
BOOTPROTO=dhcp
ONBOOT=yes
Now Restart network service by typing below command.
systemctl restart network Now your server will get IP Address from DHCP

» Static configuration

Step 3 » For Static IP.
Find the below lines in config File.
BOOTPROTO=none
ONBOOT=no
and replace with
BOOTPROTO=static
ONBOOT=yes
And add the below lines at the end of the file.
IPADDR=172.27.0.32
NETMASK=255.255.255.0
GATEWAY=172.27.0.1
DNS1=172.27.0.5
File will look like below after changes.
TYPE=Ethernet
BOOTPROTO=static
DEFROUTE=yes
IPV4_FAILURE_FATAL=no
IPV6INIT=yes
IPV6_AUTOCONF=yes
IPV6_DEFROUTE=yes
IPV6_FAILURE_FATAL=no
NAME=enp0s17
UUID=f0c5b37d-299a-43cb-b74b-618bb252d129
ONBOOT=yes
HWADDR=00:0C:29:A1:B5:CC
IPV6_PEERDNS=yes
IPV6_PEERROUTES=yes
IPADDR=192.168.1.10
NETMASK=255.255.255.0
GATEWAY=192.168.1.1
DNS1=192.168.1.5

Now Restart network service by typing below command.
systemctl restart networkNow Interface will have static IP.
Additionally you can use /etc/sysconfig/network file for hostname and DNS .
HOSTNAME=server.krizna.com
DNS1=192.168.1.5
DNS2=8.8.8.8
SEARCH=krizna.com

Have a nice day

Configuring Web Proxy on CentOS

Original Post:  http://www.thesysadminhimself.com/2013/08/configuring-web-proxy-on-centos.html

If your internet connection is behind a web proxy, you need to configure the following on your CentOS server:

System-wide proxy settings – add the following lines to your /etc/environment file:

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# vi /etc/environment
no_proxy=".mylan.local,.domain1.com,host1,host2"

To apply these settings without restarting the machine run the following commands on the bash shell:

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export http_proxy="http://proxysrv:8080/"
export https_proxy="https://proxysrv:8080/"
export ftp_proxy="ftp://proxysrv:8080/"
export no_proxy=".mylan.local,.domain1.com,host1,host2"

You also need to configure yum:

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# vi /etc/yum.conf
proxy=http://proxysrv:8080/

Remove the ending / in the yum.conf line. yum did not work with it on the proxy line. Should be like proxy=http://proxysrv:8080

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