I thought I had solved the problem :-/
I am getting data now, but the data is not complete.
When I use len() to display the length of the received data, it is always different for the same lql request (output about 1000 services). Also converting to json/pyton is not possible because the data is not complete.
$ echo -e "GET services\nColumns: host_name host_alias host_address plugin_output host_filename\nFilter: check_command = check_mk-snmp_info_v2\nOutputFormat: python\n\n" | openssl s_client -connect x.x.x.x:6558 -ign_eof -quiet | wc -c
198656
$ echo -e "GET services\nColumns: host_name host_alias host_address plugin_output host_filename\nFilter: check_command = check_mk-snmp_info_v2\nOutputFormat: python\n\n" | openssl s_client -connect x.x.x.x:6558 -ign_eof -quiet | wc -c
280576
$ echo -e "GET services\nColumns: host_name host_alias host_address plugin_output host_filename\nFilter: check_command = check_mk-snmp_info_v2\nOutputFormat: python\n\n" | openssl s_client -connect x.x.x.x:6558 -ign_eof -quiet | wc -c
198656
$ echo -e "GET services\nColumns: host_name host_alias host_address plugin_output host_filename\nFilter: check_command = check_mk-snmp_info_v2\nOutputFormat: python\n\n" | openssl s_client -connect x.x.x.x:6558 -ign_eof -quiet | wc -c
231424
$ echo -e "GET services\nColumns: host_name host_alias host_address plugin_output host_filename\nFilter: check_command = check_mk-snmp_info_v2\nOutputFormat: python\n\n" | openssl s_client -connect x.x.x.x:6558 -ign_eof -quiet | wc -c
296960
is that a bug from livestatus?