AW: Problem with replication

Hi

We are running Pg Version 9.6

On OS Centos 7 running on a VM (Nutanix)

We are trying to build a slave server on this platform. The relevant IP entry for replication has been placed in pg_hba.conf on the master. We run pg_basebackup successfully and then set up recovery.conf etc and re-start 

the slave database. It seems to process the WALs and then enter the read only state when it then generates the following errors;

Mar 23 15:22:48 xds-data1-temp postgres[13072]: [2-1] user=,db=,app=client= LOG:  database system is ready to accept read only connections

Mar 23 15:22:49 xds-data1-temp postgres[13083]: [3-1] user=[unknown],db=[unknown],app=[unknown]client=[local] LOG:  connection received: host=[local]

Mar 23 15:22:49 xds-data1-temp postgres[13083]: [4-1] user=postgres,db=[unknown],app=[unknown]client=[local] FATAL:  no pg_hba.conf entry for replication connection from host "[local]", user "postgres", SSL off

Mar 23 15:22:49 xds-data1-temp postgres[13082]: [3-1] user=,db=,app=client= FATAL:  could not connect to the primary server: FATAL:  no pg_hba.conf entry for replication connection from host "[local]", user "postgres", SSL off

Mar 23 15:22:49 xds-data1-temp postgres[13082]: [3-2]

Mar 23 15:22:49 xds-data1-temp postgres[13085]: [3-1] user=[unknown],db=[unknown],app=[unknown]client=[local] LOG:  connection received: host=[local]

Mar 23 15:22:49 xds-data1-temp postgres[13085]: [4-1] user=postgres,db=[unknown],app=[unknown]client=[local] FATAL:  no pg_hba.conf entry for replication connection from host "[local]", user "postgres", SSL off

Mar 23 15:22:49 xds-data1-temp postgres[13084]: [3-1] user=,db=,app=client= FATAL:  could not connect to the primary server: FATAL:  no pg_hba.conf entry for replication connection from host "[local]", user "postgres", SSL off

We know that the entry is in the hba and have checked for typos, but one thing that does stick out with one line on the message is; 

    FATAL:  no pg_hba.conf entry for replication connection from host "[local]" 

Other messages I have seen in the past would normally have an IP address where is says "[local]"

Any ideas as to where we might be going wrong?    

Many thanks