from lxml import etree
from StringIO import StringIO
f=open('xmltest2.xml')
xml=f.read()
print xml
tree = etree.parse(StringIO(xml))
nodes_nmap=tree.xpath('//nmaprun/host/ports/port[@protocol="tcp"]')
print "len=", len(nodes_nmap)
print nodes_nmap
for node in nodes_nmap: # perebrat elemeny
    #print node.tag,node.keys(),node.values()
    print node.values()