Chapter 4. Configuring External Services

1. On a Red Hat Enterprise Linux Server server, install the ISC DHCP Service and Berkeley Internet Name Domain (BIND) packages:

   # yum install dhcp bind

2. Generate a security token:

   # dnssec-keygen -a HMAC-MD5 -b 512 -n HOST omapi_key

   As a result, a key pair that consists of two files is created in the current directory.

3. Copy the secret hash from the key:

   # cat Komapi_key.+*.private |grep ^Key|cut -d ' ' -f2

4. Edit the dhcpd configuration file for all of the subnets and add the key. The following is an example:

   # cat /etc/dhcp/dhcpd.conf
   default-lease-time 604800;
   max-lease-time 2592000;
   log-facility local7;
   
   subnet 192.168.38.0 netmask 255.255.255.0 {
   	range 192.168.38.10 192.168.38.100;
   	option routers 192.168.38.1;
   	option subnet-mask 255.255.255.0;
   	option domain-search "virtual.lan";
   	option domain-name "virtual.lan";
   	option domain-name-servers 8.8.8.8;
   }
   
   omapi-port 7911;
   key omapi_key {
   	algorithm HMAC-MD5;
   	secret "jNSE5YI3H1A8Oj/tkV4...A2ZOHb6zv315CkNAY7DMYYCj48Umw==";
   };
   omapi-key omapi_key;

   Note that the option routers value is the Satellite or Capsule IP address that you want to use with an external DHCP service.

5. Delete the two key files from the directory that they were created in.

6. On Satellite Server, define each subnet. Do not set DHCP Capsule for the defined Subnet yet.

   To prevent conflicts, set up the lease and reservation ranges separately. For example, if the lease range is 192.168.38.10 to 192.168.38.100, in the Satellite web UI define the reservation range as 192.168.38.101 to 192.168.38.250.

7. Configure the firewall for external access to the DHCP server:

   # firewall-cmd --add-service dhcp \
   && firewall-cmd --runtime-to-permanent

8. On Satellite Server, determine the UID and GID of the foreman user:

   # id -u foreman
   993
   # id -g foreman
   990

9. On the DHCP server, create the foreman user and group with the same IDs as determined in a previous step:

   # groupadd -g 990 foreman
   # useradd -u 993 -g 990 -s /sbin/nologin foreman

10. To ensure that the configuration files are accessible, restore the read and execute flags:

    # chmod o+rx /etc/dhcp/
    # chmod o+r /etc/dhcp/dhcpd.conf
    # chattr +i /etc/dhcp/ /etc/dhcp/dhcpd.conf

11. Start the DHCP service:

    # systemctl start dhcpd

12. Export the DHCP configuration and lease files using NFS:

    # yum install nfs-utils
    # systemctl enable rpcbind nfs-server
    # systemctl start rpcbind nfs-server nfs-lock nfs-idmapd

13. Create directories for the DHCP configuration and lease files that you want to export using NFS:

    # mkdir -p /exports/var/lib/dhcpd /exports/etc/dhcp

14. To create mount points for the created directories, add the following line to the /etc/fstab file:

    /var/lib/dhcpd /exports/var/lib/dhcpd none bind,auto 0 0
    /etc/dhcp /exports/etc/dhcp none bind,auto 0 0

15. Mount the file systems in /etc/fstab:

    # mount -a

16. Ensure the following lines are present in /etc/exports:

    /exports 192.168.38.1(rw,async,no_root_squash,fsid=0,no_subtree_check)
    
    /exports/etc/dhcp 192.168.38.1(ro,async,no_root_squash,no_subtree_check,nohide)
    
    /exports/var/lib/dhcpd 192.168.38.1(ro,async,no_root_squash,no_subtree_check,nohide)

    Note that the IP address that you enter is the Satellite or Capsule IP address that you want to use with an external DHCP service.

17. Reload the NFS server:

    # exportfs -rva

18. Configure the firewall for the DHCP omapi port 7911:

    # firewall-cmd --add-port="7911/tcp" \
    && firewall-cmd --runtime-to-permanent

19. Optional: Configure the firewall for external access to NFS.

    Clients are configured using NFSv3.

    • Use the firewalld NFS service to configure the firewall:

      # firewall-cmd --zone public --add-service mountd \
      && firewall-cmd --zone public --add-service rpc-bind \
      && firewall-cmd --zone public --add-service nfs \
      && firewall-cmd --runtime-to-permanent

1. Install the nfs-utils utility:

   # yum install nfs-utils

2. Create the DHCP directories for NFS:

   # mkdir -p /mnt/nfs/etc/dhcp /mnt/nfs/var/lib/dhcpd

3. Change the file owner:

   # chown -R foreman-proxy /mnt/nfs

4. Verify communication with the NFS server and the Remote Procedure Call (RPC) communication paths:

   # showmount -e DHCP_Server_FQDN
   # rpcinfo -p DHCP_Server_FQDN

5. Add the following lines to the /etc/fstab file:

   DHCP_Server_FQDN:/exports/etc/dhcp /mnt/nfs/etc/dhcp nfs
   ro,vers=3,auto,nosharecache,context="system_u:object_r:dhcp_etc_t:s0" 0 0
   
   DHCP_Server_FQDN:/exports/var/lib/dhcpd /mnt/nfs/var/lib/dhcpd nfs
   ro,vers=3,auto,nosharecache,context="system_u:object_r:dhcpd_state_t:s0" 0 0

6. Mount the file systems on /etc/fstab:

   # mount -a

7. To verify that the foreman-proxy user can access the files that are shared over the network, display the DHCP configuration and lease files:

   # su foreman-proxy -s /bin/bash
   bash-4.2$ cat /mnt/nfs/etc/dhcp/dhcpd.conf
   bash-4.2$ cat /mnt/nfs/var/lib/dhcpd/dhcpd.leases
   bash-4.2$ exit

8. Enter the satellite-installer command to make the following persistent changes to the /etc/foreman-proxy/settings.d/dhcp.yml file:

   # satellite-installer --foreman-proxy-dhcp=true \
   --foreman-proxy-dhcp-provider=remote_isc \
   --foreman-proxy-plugin-dhcp-remote-isc-dhcp-config /mnt/nfs/etc/dhcp/dhcpd.conf \
   --foreman-proxy-plugin-dhcp-remote-isc-dhcp-leases /mnt/nfs/var/lib/dhcpd/dhcpd.leases \
   --foreman-proxy-plugin-dhcp-remote-isc-key-name=omapi_key \
   --foreman-proxy-plugin-dhcp-remote-isc-key-secret=jNSE5YI3H1A8Oj/tkV4...A2ZOHb6zv315CkNAY7DMYYCj48Umw== \
   --foreman-proxy-plugin-dhcp-remote-isc-omapi-port=7911 \
   --enable-foreman-proxy-plugin-dhcp-remote-isc \
   --foreman-proxy-dhcp-server=DHCP_Server_FQDN

9. Restart the foreman-proxy service:

   # systemctl restart foreman-proxy

10. Log in to the Satellite Server web UI.
11. Navigate to Infrastructure > Capsules. Locate the Capsule Server that you want to configure with external DHCP, and from the list in the Actions column, select Refresh.
12. Associate the DHCP service with the appropriate subnets and domain.

Before you Begin.

1. Confirm the IdM server is deployed and the host-based firewall has been configured correctly. For more information, see Port Requirements in the Linux Domain Identity, Authentication, and Policy Guide.
2. Obtain an account on the IdM server with permissions to create zones on the IdM server.
3. Confirm if the Satellite or an external Capsule is managing DNS for a domain.
4. Confirm that the Satellite or external Capsule are currently working as expected.
5. In the case of a newly installed system, complete the installation procedures in this guide first. In particular, DNS and DHCP configuration should have been completed.
6. Make a backup of the answer file in case you have to revert the changes. See Specifying Installation Options for more information.

Create a Kerberos Principal on the IdM Server.

1. Ensure you have a Kerberos ticket.

   # kinit idm_user

   Where idm_user is the account created for you by the IdM administrator.

2. Create a new Kerberos principal for the Satellite or Capsule to use to authenticate to the IdM server.

   # ipa service-add capsule/satellite.example.com

1. Install the ipa-client package on Satellite Server or Capsule Server:

   • On Satellite Server, enter the following command:

     # satellite-maintain packages install ipa-client

   • On Capsule Server, enter the following command:

     # yum install ipa-client

2. Configure the IdM client by running the installation script and following the on-screen prompts.

   # ipa-client-install

3. Ensure you have a Kerberos ticket.

   # kinit admin

4. Remove any preexisting keytab.

   # rm /etc/foreman-proxy/dns.keytab

5. Get the keytab created for this system.

   # ipa-getkeytab -p capsule/satellite.example.com@EXAMPLE.COM \
   -s idm1.example.com -k /etc/foreman-proxy/dns.keytab

   Note

   When adding a keytab to a standby system with the same host name as the original system in service, add the r option to prevent generating new credentials and rendering the credentials on the original system invalid.

6. Set the group and owner for the keytab file to foreman-proxy as follows.

   # chown foreman-proxy:foreman-proxy /etc/foreman-proxy/dns.keytab

7. If required, check the keytab is valid.

   # kinit -kt /etc/foreman-proxy/dns.keytab \
   capsule/satellite.example.com@EXAMPLE.COM

Configure DNS Zones in the IdM web UI.

1. Create and configure the zone to be managed:

   1. Navigate to Network Services > DNS > DNS Zones.
   2. Select Add and enter the zone name. In this example, example.com.
   3. Click Add and Edit.

   4. On the Settings tab, in the BIND update policy box, add an entry as follows to the semi-colon separated list.

      grant capsule\047satellite.example.com@EXAMPLE.COM wildcard * ANY;

   5. Ensure Dynamic update is set to True.
   6. Enable Allow PTR sync.
   7. Select Save to save the changes.

2. Create and Configure the reverse zone.

   1. Navigate to Network Services > DNS > DNS Zones.
   2. Select Add.
   3. Select Reverse zone IP network and add the network address in CIDR format to enable reverse lookups.
   4. Click Add and Edit.

   5. On the Settings tab, in the BIND update policy box, add an entry as follows to the semi-colon separated list:

      grant capsule\047satellite.example.com@EXAMPLE.COM wildcard * ANY;

   6. Ensure Dynamic update is set to True.
   7. Select Save to save the changes.

1. Navigate to Infrastructure > Capsules.
2. For each Capsule to be updated, from the Actions drop-down menu, select Refresh.

3. Configure the domain:

   1. Go to Infrastructure > Domains and select the domain name.
   2. On the Domain tab, ensure DNS Capsule is set to the Capsule where the subnet is connected.

4. Configure the subnet:

   1. Go to Infrastructure > Subnets and select the subnet name.
   2. On the Subnet tab, set IPAM to None.
   3. On the Domains tab, ensure the domain to be managed by the IdM server is selected.
   4. On the Capsules tab, ensure Reverse DNS Capsule is set to the Capsule where the subnet is connected.
   5. Click Submit to save the changes.

Before you Begin

1. Confirm the IdM Server is deployed and the host-based firewall has been configured correctly. For more information, see Port Requirements in the Linux Domain Identity, Authentication, and Policy Guide.
2. Obtain root user privileges on the IdM server.
3. Confirm if the Satellite or an external Capsule is managing DNS for a domain.
4. Confirm that the Satellite or external Capsule are currently working as expected.
5. In the case of a newly installed system, complete the installation procedures in this guide first. In particular, DNS and DHCP configuration should have been completed.
6. Make a backup of the answer file in case you have to revert the changes. See Specifying Installation Options for more information.

Enabling External Updates to the DNS Zone in the IdM Server

1. On the IdM Server, add the following to the top of the /etc/named.conf file.

   // This was added to allow Satellite Server at 192.168.25.1 to make DNS updates.
   ########################################################################
   include "/etc/rndc.key";
   controls  {
   inet 192.168.25.2 port 953 allow { 192.168.25.1; } keys { "rndc-key"; };
   };
   ########################################################################

2. Reload named to make the changes take effect.

   # systemctl reload named

3. In the IdM web UI, go to Network Services > DNS > DNS Zones. Select the name of the zone. On the Settings tab:

   1. Add the following in the BIND update policy box.

      grant "rndc-key" zonesub ANY;

   2. Ensure Dynamic update is set to True.
   3. Click Update to save the changes.

4. Copy the /etc/rndc.key file from the IdM server to Satellite’s base system as follows.

   # scp /etc/rndc.key root@satellite.example.com:/etc/rndc.key

5. Ensure that the ownership, permissions, and SELinux context are correct.

   # restorecon -v /etc/rndc.key
   # chown -v root:named /etc/rndc.key
   # chmod -v 640 /etc/rndc.key

6. On Satellite Server, run the installation script as follows to use the external DNS server.

   # satellite-installer --scenario satellite \
   --foreman-proxy-dns=true \
   --foreman-proxy-dns-managed=false \
   --foreman-proxy-dns-provider=nsupdate \
   --foreman-proxy-dns-server="192.168.25.2" \
   --foreman-proxy-keyfile=/etc/rndc.key \
   --foreman-proxy-dns-ttl=86400

Testing External Updates to the DNS Zone in the IdM Server

1. Install bind-utils for testing with nsupdate.

   # yum install bind-utils

2. Ensure the key in the /etc/rndc.key file on Satellite Server is the same one as used on the IdM server.

   key "rndc-key" {
           algorithm hmac-md5;
           secret "secret-key==";
   };

3. On Satellite Server, create a test DNS entry for a host. For example, host test.example.com with an A record of 192.168.25.20 on the IdM server at 192.168.25.1.

   # echo -e "server 192.168.25.1\n \
   update add test.example.com 3600 IN A 192.168.25.20\n \
   send\n" | nsupdate -k /etc/rndc.key

4. On Satellite Server, test the DNS entry.

   # nslookup test.example.com 192.168.25.1
   Server:		192.168.25.1
   Address:	192.168.25.1#53
   
   Name:	test.example.com
   Address: 192.168.25.20

5. To view the entry in the IdM web UI, go to Network Services > DNS > DNS Zones. Select the name of the zone and search for the host by name.

6. If resolved successfully, remove the test DNS entry.

   # echo -e "server 192.168.25.1\n \
   update delete test.example.com 3600 IN A 192.168.25.20\n \
   send\n" | nsupdate -k /etc/rndc.key

7. Confirm that the DNS entry was removed.

   # nslookup test.example.com 192.168.25.1

   The above nslookup command fails and returns the SERVFAIL error message if the record was successfully deleted.

1. Navigate to Infrastructure > Capsules.
2. For each Capsule to be updated, from the Actions drop-down menu, select Refresh.

3. Configure the domain:

   1. Go to Infrastructure > Domains and select the domain name.
   2. On the Domain tab, ensure DNS Capsule is set to the Capsule where the subnet is connected.

4. Configure the subnet:

   1. Go to Infrastructure > Subnets and select the subnet name.
   2. On the Subnet tab, set IPAM to DHCP or Internal DB.
   3. On the Domains tab, ensure the domain to be managed by the Satellite or Capsule is selected.
   4. On the Capsules tab, ensure Reverse DNS Capsule is set to the Capsule where the subnet is connected.
   5. Click Submit to save the changes.