Ruling on renting out unlimited space on the Internet and hosting websites
Question

                I book large spaces on Internet servers for one year, and I renew it annually. Then I divide it up and sell it to website owners in return for an annual or monthly fee. Now I am preparing limited spaces, i.e., spaces of a known size. There are companies who make exhibitions that use an unknown amount of space, but it is allowed for the customer to upload as much as he wants onto the website, subject to conditions such as being fair, but without defining how much space. In fact there is no such thing as unlimited storage space; rather this is just advertising to attract customers, and there is no definition of the amount of material the customer can upload, subject to the conditions, as I have explained.

I would like to know: is this transaction halaal or is there any concern about its permissibility?.
Praise be to Allah.
    There is nothing wrong with renting a known amount of space 
    on Internet servers, then dividing it up and renting it out to website 
    owners for an annual or monthly fee. 

    As for renting unlimited space, that is not valid, because 
    the condition of rental contracts and sales is that it should be known what 
    the thing is that is being rented or purchased. Not knowing constitutes 
    ambiguity and risk, each of which may lead to disputes. Hence sharee‘ah does 
    not permit that. 

    Muslim (1513) narrated that Abu Hurayrah said: The Messenger 
    of Allah (blessings and peace of Allah be upon him) forbade transactions 
    involving ambiguity. 

    Ambiguity means not knowing what is being bought or rented, 
    and taking risks, which leads to disputes. 

    In al-Mawsoo‘ah al-Fiqhiyyah (30/224) it says: it is 
    stipulated that the object of the contract should be defined and known to 
    both parties, so that there are no unknown elements that could lead to 
    dispute and ambiguity. Having knowledge of the object of the contract and 
    distinguishing it from other things is achieved by seeing it or part of it 
    at the time of the contract, or by describing it in such a way that explains 
    exactly what it is, or by pointing at it. This condition is unanimously 
    agreed upon among the fuqaha’ with regard to contracts of buying and selling 
    in general. So it is not permissible to sell “a sheep in the flock (without 
    identifying a particular sheep)” for example, or to rent out “one of these 
    two houses”. That is because not knowing what the object of the contract is 
    leads to ambiguity and disputes. With regard to this matter, some fuqaha’ 
    differentiated between having no knowledge of the object of the transaction, 
    which is what leads to disputes, and having no knowledge about a little of 
    the object of the transaction, which does not lead to disputes. So they 
    forbade the former and permitted the latter. End quote. 

    And Allah knows best.