Upgrade Nginx Insight Guide Adding Additional IP Addresses

Adding additional IPs to a server involves 2 main tasks

1. Adding and registering additional IPs to system network configuration
2. Configuring Nginx to use those additional IPs

Additional IPs System Configuration

For CentOS to add additional IP address, you need to first be assigned additional IP addresses by your web host or order the additional IPs. For instance, OVH calls additional IPs failover IPs.

OVH has a guide for adding and registering the additional IPs for CentOS and other Linux distributions to the system outlined at Network IP Aliasing | OVH Docs.

There's a previous discussion for this with tips at https://community.centminmod.com/threads/how-to-add-a-ipv4-failover-range-to-centos-7.8691/ including scripting the format for each
/etc/sysconfig/network-scripts/ifcfg-eth0:X file you need to create.

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Example for CentOS 6 & 7

Example IP range 192.168.2.2 to 192.168.2.10 in SSH or shell script define IPLIST variable listing all additional IP addresses in single space separated list and define i variable with starting value of 0. Then a for ip in $IPLIST loop incrementing i variable by 1 for each IP listed in IPLIST

Code (Text):

IPLIST="192.168.2.2 192.168.2.3 192.168.2.4 192.168.2.5 192.168.2.6 192.168.2.7 192.168.2.8 192.168.2.9 192.168.2.10"
i=0
for ip in $IPLIST; do
  i=$(($i+1))
echo -e "\n/etc/sysconfig/network-scripts/ifcfg-eth0:${i}"; echo "
DEVICE="eth0:$i"
BOOTPROTO=static
IPADDR="$ip"
NETMASK="255.255.255.255"
BROADCAST="xxx.xxx.xxx.xxx"
ONBOOT=yes";
echo -e "\nifup eth0:${i}";
done

Gives following display only output

Code (Text):

/etc/sysconfig/network-scripts/ifcfg-eth0:2

DEVICE=eth0:2
BOOTPROTO=static
IPADDR=192.168.2.2
NETMASK=255.255.255.255
BROADCAST=xxx.xxx.xxx.xxx
ONBOOT=yes

ifup eth0:2

/etc/sysconfig/network-scripts/ifcfg-eth0:3

DEVICE=eth0:3
BOOTPROTO=static
IPADDR=192.168.2.3
NETMASK=255.255.255.255
BROADCAST=xxx.xxx.xxx.xxx
ONBOOT=yes

ifup eth0:3

/etc/sysconfig/network-scripts/ifcfg-eth0:4

DEVICE=eth0:4
BOOTPROTO=static
IPADDR=192.168.2.4
NETMASK=255.255.255.255
BROADCAST=xxx.xxx.xxx.xxx
ONBOOT=yes

ifup eth0:4

/etc/sysconfig/network-scripts/ifcfg-eth0:5

DEVICE=eth0:5
BOOTPROTO=static
IPADDR=192.168.2.5
NETMASK=255.255.255.255
BROADCAST=xxx.xxx.xxx.xxx
ONBOOT=yes

ifup eth0:5

/etc/sysconfig/network-scripts/ifcfg-eth0:6

DEVICE=eth0:6
BOOTPROTO=static
IPADDR=192.168.2.6
NETMASK=255.255.255.255
BROADCAST=xxx.xxx.xxx.xxx
ONBOOT=yes

ifup eth0:6

/etc/sysconfig/network-scripts/ifcfg-eth0:7

DEVICE=eth0:7
BOOTPROTO=static
IPADDR=192.168.2.7
NETMASK=255.255.255.255
BROADCAST=xxx.xxx.xxx.xxx
ONBOOT=yes

ifup eth0:7

/etc/sysconfig/network-scripts/ifcfg-eth0:8

DEVICE=eth0:8
BOOTPROTO=static
IPADDR=192.168.2.8
NETMASK=255.255.255.255
BROADCAST=xxx.xxx.xxx.xxx
ONBOOT=yes

ifup eth0:8

/etc/sysconfig/network-scripts/ifcfg-eth0:9

DEVICE=eth0:9
BOOTPROTO=static
IPADDR=192.168.2.9
NETMASK=255.255.255.255
BROADCAST=xxx.xxx.xxx.xxx
ONBOOT=yes

ifup eth0:9

/etc/sysconfig/network-scripts/ifcfg-eth0:10

DEVICE=eth0:10
BOOTPROTO=static
IPADDR=192.168.2.10
NETMASK=255.255.255.255
BROADCAST=xxx.xxx.xxx.xxx
ONBOOT=yes

ifup eth0:10

Where the first entry /etc/sysconfig/network-scripts/ifcfg-eth0:2 would contain

Code (Text):

DEVICE=eth0:2
BOOTPROTO=static
IPADDR=192.168.2.2
NETMASK=255.255.255.255
BROADCAST=xxx.xxx.xxx.xxx
ONBOOT=yes

and command to start up the interface for initial first time for eth0:2 would be

Code (Text):

ifup eth0:2

Example for CentOS 7 Only

For CentOS 7 there's a 2nd method for adding additional IPs to your system https://www.unixmen.com/linux-basic...esses-single-network-interface-card-centos-7/. Instead of separate /etc/sysconfig/network-scripts/ifcfg-eth0:X files where X increments, you add additional IPs within the same /etc/sysconfig/network-scripts/ifcfg-eth0 existing file defined by variable IPADDRx where x increments from 1 to number of IP addresses you want to add. Your file might not be named eth0 as it depends on your CentOS 7 network device naming scheme which you can find out via command below to check which network device belongs to your existing public IP address for your server:

Code (Text):

ifconfig

So if you existing /etc/sysconfig/network-scripts/ifcfg-eth0 file contain

Code (Text):

DEVICE=eth0
BOOTPROTO=static
IPADDR=192.168.2.1
NETMASK=255.255.255.255
BROADCAST=xxx.xxx.xxx.xxx
ONBOOT=yes

adding additional example IPs above would add these additional entries

Code (Text):

IPADDR1=192.168.2.2
IPADDR2=192.168.2.3
IPADDR3=192.168.2.4
IPADDR4=192.168.2.5
IPADDR5=192.168.2.6
IPADDR6=192.168.2.7
IPADDR7=192.168.2.8
IPADDR8=192.168.2.9
IPADDR9=192.168.2.10

so /etc/sysconfig/network-scripts/ifcfg-eth0 file with additional IPs would contain

Code (Text):

DEVICE=eth0
BOOTPROTO=static
IPADDR0=192.168.2.1
IPADDR1=192.168.2.2
IPADDR2=192.168.2.3
IPADDR3=192.168.2.4
IPADDR4=192.168.2.5
IPADDR5=192.168.2.6
IPADDR6=192.168.2.7
IPADDR7=192.168.2.8
IPADDR8=192.168.2.9
IPADDR9=192.168.2.10
NETMASK=255.255.255.255
BROADCAST=xxx.xxx.xxx.xxx
ONBOOT=yes

again you can script for this IPLIST variable defining space separated list of additional IP addresses in a for ip in $IPLIST loop with starting i=0 variable that increments by a value of 1 for each IPLIST entry

Code (Text):

IPLIST="192.168.2.2 192.168.2.3 192.168.2.4 192.168.2.5 192.168.2.6 192.168.2.7 192.168.2.8 192.168.2.9 192.168.2.10"
i=0
for ip in $IPLIST; do
  i=$(($i+1))
  echo "IPADDR${i}=$ip"
done

changing existing IPADDR line from

Code (Text):

IPADDR=192.168.2.1

to

Code (Text):

IPADDR0=192.168.2.1

Then restart your networking service

Code (Text):

service network restart

check the additional IPs registered on your system via command

Code (Text):

ifconfig

 

Configuring Nginx Additional IP Usage

To configure Nginx additional IPs, you need to first do the above to add the additional IPs to the system's networking configuration and for the IPs to show up in ifconfig output and be pingable. Nginx can setup Vhosts to use either name based hosting (default) sharing the main IP address or IP based hosting where a Vhost uses a dedicated or different IP address from the main IP address. This is controlled by Nginx listen directive How nginx processes a request

SECOND_IP

Centmin Mod 123.09beta01 and higher have native support to configure Nginx vhost creation routines to use a separate second IP from the main server IP address via persistent config file /etc/centminmod/custom_config.inc set variable called SECOND_IP discussed and added at https://community.centminmod.com/th...r-routines-support-second-ip.5292/#post-22203. So out of the box, new nginx vhosts generated will use the defined SECOND_IP=111.222.333.444 where the IP is a secondary IP addressed added to the server.

You define SECOND_IP variable is centmin mod persistent config file outlined at Upgrade Centmin Mod - CentminMod.com LEMP Nginx web stack for CentOS you manually create the file at /etc/centminmod/custom_config.inc and add SECOND_IP=yoursecondary_IPaddress variable to it which will be registered with nginx vhost generator routine so that any new nginx vhosts created via centmin.sh menu option 2 or /usr/bin/nv or centmin.sh menu option 22, will have pre-defined SECOND_IP ip address set in the nginx vhost's listen directive.

So in persistent config file you create or already created at /etc/centminmod/custom_config.inc set in it

Code (Text):

SECOND_IP=111.222.333.444

So at centmin.sh menu option 2, 22 or nv command runs to create a fresh new Nginx vhost instead of server{} context's listen directive being listed as

Code (Text):

listen 80;

with SECOND_IP set it will become

Code (Text):

listen 111.222.333.444:80;

for HTTPS on port 443

instead of

Code (Text):

listen 443;

with SECOND_IP set it will become

Code (Text):

listen 111.222.333.444:443;

where you defined SECOND_IP=111.222.333.444

Thus allowing you to use a different server IP for new nginx vhosts generated automatically when you run centmin.sh menu options 2, 22 or nv command line.

Nginx Vhost Manual Configuration

Now if you want to use a different IP address from main server IP or the one defined in SECOND_IP variable, then right now you would need to manually edit your Nginx vhost config file's listen directive yourself defining the additional IP you added earlier. So if a 3rd additional IP address is 111.222.333.555, your nginx vhost's listen directive would be like the following:

for port 80

Code (Text):

listen 111.222.333.555:80;

or for port 443

Code (Text):

listen 111.222.333.555:443;

and restart Nginx server afterwards

Code (Text):

service nginx restart

or centmin mod command shortcut

Code (Text):

ngxrestart

 

what does output for nginx config test show

Code (Text):

nginx -t

for posting code or output from commands to keep the formatting, you might want to use CODE tags for code How to use forum BBCODE code tags
have you checked if your IPv6 addresses are working first and properly added ? Can you ping them via ping6 ? i.e.

Code (Text):

ping6 -c4 2a00:dcc0:dead:xxxx::1 -I eth0

changing eth0 to the internet the IPv6 is assigned to
Does existing IPv6 addresses assigned work and are pingable ?

 

Or just set nginx to listen on all IPv6

Code (Text):

listen [::]:80 ipv6only=on

and set DNS AAAA record for specific IPv6 for the domain

also you should only set the ipv6only directive once per listen port number regardless of the number of Nginx vhost sites you have

 

as previous post you should only set the ipv6only directive once per listen port number regardless of the number of Nginx vhost sites you have so only one nginx vhost needs ipv6only=on per ip/port pair otherwise you get duplicate listen options error

 

SECOND_IP should work but you need to add the 2nd IP itself to your CentOS system's network configuration as well. If you haven't done so, the 2nd IP won't have network routing working.

 

strange then it should of worked as long as domain name's DNS A record for non-www and www versions pointed to 2nd IP address

 

best to start a new thread in the DNS subforum at Domains, DNS, Email & SSL Certificates with info asked in sticky thread at SSL - Domains - Letsencrypt - How too troubleshoot Letsencrypt SSL certificate issuance or renewal