<xsl:for-each select="root/host">
<xsl:value-of select="address/@addr"/>
<xsl:for-each select="ports/port">
<xsl:value-of select="@portid"/>
</xsl:for-each>
</xsl:for-each>
you can try above on some sample xslt editor like http://www.w3schools.com/xsl/tryxslt.asp?xmlfile=cdcatalog&xsltfile=cdcatalog_ex3