How to get SNMP credentials for own check in check_mk 1.6

Sorry but I don’t understand your way.
I have set the credentials in the properties of the host and need to access the properties in the python script of the check, witch is a customization of the original check_mk check sni_octopuse_trunks:

#.1.3.6.1.4.1.231.7.2.9.3.8.1.3.1  "OpenStage 30"
#.1.3.6.1.4.1.231.7.2.9.3.8.1.3.2  "OpenStage 30"
#.1.3.6.1.4.1.231.7.2.9.3.8.1.3.7  "P. O. T."
#.1.3.6.1.4.1.231.7.2.9.3.8.1.3.9  "S0 extension"
#.1.3.6.1.4.1.231.7.2.9.3.8.1.3.11  "S0 trunk: extern"
#.1.3.6.1.4.1.231.7.2.9.3.8.1.3.13  "<not configured>: extern"
#[...]
#.1.3.6.1.4.1.231.7.2.9.3.8.1.4.11  2
#.1.3.6.1.4.1.231.7.2.9.3.8.1.4.13  1

import netsnmp
import cmk_base.config as config

def inventory_siemenshipath_trunks(info):
    trunkports = [ "S0 trunk:", "CorNet NQ Trunk:" ]
    oidporttypes = netsnmp.VarList(netsnmp.Varbind('.1.3.6.1.4.1.231.7.2.9.3.8.1.3'))
    porttypes = netsnmp.snmpwalk(oidporttypes, Version=2, DestHost=host_name(), Community=config.snmp_credentials_of(host_name()))
    inventory = []
    indexI = 0
    while indexI < len(porttypes):
        for port in trunkports:
            porttype = porttypes[indexI]
            if port in porttype:
                oid = netsnmp.Varbind('.1.3.6.1.4.1.231.7.2.9.3.8.1.1.' + str(indexI+1))
                portindex = netsnmp.snmpget(oid, Version=2, DestHost=host_name(), Community=config.snmp_credentials_of(host_name()))
                oid = netsnmp.Varbind('.1.3.6.1.4.1.231.7.2.9.3.8.1.2.' + str(indexI+1))
                cardindex = netsnmp.snmpget(oid, Version=2, DestHost=host_name(), Community=config.snmp_credentials_of(host_name()))
                portdesc = "%s/%s/%s" % (cardindex[0], portindex[0], porttype)
                inventory.append((portdesc, None))
        indexI += 1
    return inventory


def check_siemenshipath_trunks(item, _no_params, info):
    perfdata = []
    cardindex, portindex, porttype = item.split('/')

    oid = netsnmp.Varbind('.1.3.6.1.4.1.231.7.2.9.3.8.1.4.' + portindex)
    portstates = netsnmp.snmpget(oid, Version=2, DestHost=host_name(), Community=config.snmp_credentials_of(host_name()))

    perfdata = [ ("Active", portstates[0], 1, 0, 0, 2) ]

    if portstates[0] == "1":
        return (2, "Port [%s] is inactive" % porttype, perfdata)
    elif portstates[0] == "2":
        return (0, "Port [%s] is active" % porttype, perfdata)

    return (3, "UNKW - unknown data received from agent", perfdata)

check_info['sni_siemenshipath_trunks'] = {
    'check_function'     : check_siemenshipath_trunks,
    'inventory_function' : inventory_siemenshipath_trunks,
    'service_description': "Trunk %s",
    "has_perfdata"            : True,
    'snmp_scan_function' : lambda oid: "agent for hipath" in \
                                  oid(".1.3.6.1.2.1.1.1.0").lower(),
    'snmp_info'          : [ (".1.3.6.1.4.1.231.7.2.9.3.8.1.4.1", []), ]
}