The annoying thing about RHEL is subscription.

If you don't apply it, you can't do yum, so you need to do it first. I will put the procedure quickly.

Premise: Customer portal account https://access.redhat.com/management/ The subscriptions available to are tied to.

If you can connect externally

You can register and apply as it is from the OS. Terminal copy and paste

[root@host01 /]# 
[root@host01 /]# subscription-manager register
Registering: subscription.rhsm.redhat.com:443/subscription
username: dango
password: 
This system was registered with the following ID: 943908a1-d1bf-4d75-b7c6-f2513122fbe4
Registered system name: host01
[root@host01 /]# 
[root@host01 /]# subscription-manager list
+-------------------------------------------+
Status of installed products
+-------------------------------------------+
product name: Red Hat Enterprise Linux Server
Product ID: 69
version: 7.5
architecture: x86_64
Status:Not subscribed
State details:Not supported by a valid subscription.
start: 
End:

[root@host01 /]# 
[root@host01 /]# subscription-manager list --available
+-------------------------------------------+
Available subscriptions
+-------------------------------------------+
Subscription name: 30 Day Red Hat Enterprise Linux Server Self-Supported Evaluation
Offer: Red Hat Beta
Oracle Java (for RHEL Server)
Red Hat Enterprise Linux Server
Red Hat Ansible Engine
Red Hat Container Images Beta
Red Hat Enterprise Linux Atomic Host Beta
Red Hat Enterprise Linux Atomic Host
Red Hat Container Images
SKU: RH00065
Agreement: 11833975
Pool ID: 8a85f99a67cdc3e701682adea40e3295
Providing management:No
quantity: 1
Recommendation: 1
service level: Self-Support
Service type: L1-L3
Subscription type: Instance Based
End:February 06, 2019
System type:Physics

[root@host01 /]# 
[root@host01 /]# subscription-manager subscribe --pool=8a85f99a67cdc3e701682adea40e3295
The subscription was assigned correctly: 30 Day Red Hat Enterprise Linux Server Self-Supported Evaluation
[root@host01 /]# 
[root@host01 /]# subscription-manager list
+-------------------------------------------+
Status of installed products
+-------------------------------------------+
product name: Red Hat Enterprise Linux Server
Product ID: 69
version: 7.5
architecture: x86_64
Status:Subscribed
State details: 
start:January 07, 2019
End:February 06, 2019

[root@host01 /]#

Use the user name and password from the management portal. The evaluation version license is applied here.

subscription-manager list --available

Check the pool IDs of the subscriptions available at

subscription-manager subscribe --pool=xxxxxxxxxx

Apply with.

After the above is completed, it will be reflected on the WEB portal. https://access.redhat.com/management/

When offline

First of all, it is necessary to do various things on the WEB of the terminal connected to the outside.

① System registration

https://access.redhat.com/management/ Go to Create a new system profile on the System tab Manually register the system to apply from.

Anyway, it doesn't connect, so anything is fine, but enter the system name and version.

② Attach subscription

From the [Subscription] tab of the registered system Click `Attach Subscription``.

An applicable subscription will appear, so attach it.

③ Download certificate

After applying, "Download Certificate" will appear next to it, so click it to download it. (Downloaded as zip)

④ Apply

Unzip the downloaded zip and place it on the computer where you want to apply the pem file inside. Assuming that it is placed in / tmp, execute the following command.

subscription-manager import --certificate=/tmp/Name_Of_Downloaded_Entitlement_Cert.pem

Certificate Name_Of_Downloaded_Entitlement_Cert.pem was successfully imported Is displayed, OK.

Verification

# subscription-manager list
+-------------------------------------------+
Status of installed products
+-------------------------------------------+
product name: Red Hat Enterprise Linux Server
Product ID: 69
version: 7.8
architecture: x86_64
Status:unknown
State details: 
start: 
End:

You can't see the status information because you're offline, but now you can run yum.

That's it.