We have some issues on the Redis configuration, we have two servers one with Redis Master configured and the another for Slave, the two servers have the sentinel configuration like this:

Master (/etc/redis/redis.conf):

bind 0.0.0.0
port 6379
slave-read-only yes
requirepass foobared
appendonly yes

Command:

redis-cli -a foobared info replication

Replication
role:master
connected_slaves:0
master_repl_offset:0
repl_backlog_active:0
repl_backlog_size:1048576
repl_backlog_first_byte_offset:0
repl_backlog_histlen:0

Redis Slave configuration (/etc/redis/redis.conf):

slaveof IP_MASTER 6379
masterauth foobared
requirepass foobared

Command:

redis-cli -a foobared info replication

Replication
role:slave
master_host:redis-0.setevoy.org.ua
master_port:6379
master_link_status:up
master_last_io_seconds_ago:5
master_sync_in_progress:0

Master Redis Sentinel (/etc/redis/sentinel.conf):

sentinel monitor redis-test IP_MASTER 6379 2
sentinel down-after-milliseconds redis-test 6001
sentinel failover-timeout redis-test 60000
sentinel parallel-syncs redis-test 1
bind 0.0.0.0
sentinel auth-pass redis-test foobared

Slave Redis Sentinel (/etc/redis/sentinel.conf):

sentinel monitor redis-test IP_MASTER 6379 2
sentinel down-after-milliseconds redis-test 6001
sentinel failover-timeout redis-test 60000
sentinel parallel-syncs redis-test 1
bind 0.0.0.0
sentinel auth-pass redis-test foobared

External machine:

redis-cli -h IP_MASTER -p 26379 info sentinel

# Sentinel
sentinel_masters:1
sentinel_tilt:0
sentinel_running_scripts:0
sentinel_scripts_queue_length:0
sentinel_simulate_failure_flags:0
master0:name=redis-test,status=ok,address=IP_MASTER:6379,slaves=1,sentinels=2

All seems working correctly but when we try with :

redis-cli -h IP_MASTER -p 26379

We always get:

IP_MASTER:26379> AUTH foobared
(error) ERR unknown command 'AUTH'

We don't know if we are missing something, any advice?