1from socket import inet_ntoa
2from struct import pack
3
4
5def calcDottedNetmask(mask):
6    bits = 0
7    for i in xrange(32 - mask, 32):
8        bits |= (1 << i)
9    packed_value = pack('!I', bits)
10    addr = inet_ntoa(packed_value)
11    return addr
12