SQL Server 2019

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CREATE TABLE test (
  "hostIp" VARCHAR(11),
  "port" INTEGER,
  "protocol" VARCHAR(3)
);

INSERT INTO test
  ("hostIp", "port", "protocol")
VALUES
  ('192.168.1.1', '80', 'tcp'),
  ('192.168.1.1', '443', 'tcp');
2 rows affected

SELECT 
    tOuter.hostIp AS [host.ip]
    ,ports = (
            SELECT
                tInner.port
               ,tInner.protocol
            FROM test tInner
            FOR JSON PATH
         )
FROM test tOuter
GROUP BY
  tOuter.hostIp
FOR JSON PATH;



JSON_F52E2B61-18A1-11d1-B105-00805F49916B


[{"host":{"ip":"192.168.1.1"},"ports":[{"port":80,"protocol":"tcp"},{"port":443,"protocol":"tcp"}]}]


SELECT 
    t.hostIp AS [host.ip]
    ,ports = JSON_QUERY('[' + STRING_AGG(tInner.json, ',') + ']')
FROM test t
CROSS APPLY (
    SELECT
        t.port
       ,t.protocol
    FOR JSON PATH, WITHOUT_ARRAY_WRAPPER
) tInner(json)
GROUP BY
  t.hostIp
FOR JSON PATH;


JSON_F52E2B61-18A1-11d1-B105-00805F49916B


[{"host":{"ip":"192.168.1.1"},"ports":[{"port":80,"protocol":"tcp"},{"port":443,"protocol":"tcp"}]}]