средство моделирования сумо показывает “переменную SUMO_HOME не набор” и “не могущее соединиться”

my@my-HP-15-Notebook-PC:~$ cd iitk/
my@my-HP-15-Notebook-PC:~/iitk$ netconvert --osm-files iitk.osm -o iitk.net.xml
Warning: Environment variable SUMO_HOME is not set, using built in type maps.
Warning: Environment variable SUMO_HOME is not set, schema resolution will use slow website lookups.
Error: unable to connect socket for URL 'http://sumo.dlr.de/xsd/types_file.xsd'
 In file 'built in type map'
 At line/column 1/0.

  The types could not be loaded from 'built in type map'.
Quitting (on error).