[Discuss] Limit the number of ip addresses which can connect to a port

[invalid at pizzashack.org (Derek Martin)]

Write a small server that does the ACL management you want, and
proxies the user request to the real server.  Run the actual server on
a different port that's firewalled off to the outside world and/or
only binds on localhost.

-- 
Derek D. Martin    http://www.pizzashack.org/   GPG Key ID: 0xDFBEAD02
-=-=-=-=-
This message is posted from an invalid address.  Replying to it will result in
undeliverable mail due to spam prevention.  Sorry for the inconvenience.


On Wed, Nov 01, 2017 at 12:31:43PM -0400, Tom Luo wrote:
> Hi, Derek,
> 
> Thanks for your suggestions. However, this is not exactly what I want.
> The service is running in the server. Users can only connect to the server
> using an assigned TCP port and a password.
> This service using port/password to identify a user. Different users will
> get different ports and their own unique password.
> For example, user A will connect to port 8001 using password "testpassword".
> User B will connect to port 8002 using password "testpassword2".
> Every user has to pay a fee to use the service.
> This works very well if no user shares port/password with other people.
> To reduce this passowrd/port sharing issue, I propose to limit the number
> of ip addresses connected to a port.
> If a user A (assigned port 8010) shares his/her password with a person C,
> user A can connect to port 8010 and use the service.
> If at the same time the person C tries to connect to port 8010 from another
> ip address. the firewall should decline the new connection.
> I also check the connections and I see one user can have many connections
> to the assigned port at the same time. So, I cannot use the number of
> active connections on a port to solve this issue.
> The only thing I can think about is using IP address. I think video service
> providers like hulu and netflix face the same issue. But, I don't know how
> they deal with the password sharing issue.
> 
> I hope I explained the issue clearly. BTW, I don't have the source code of
> the service, so I cannot change the service itself.
> 
> Thanks a lot!
> 
> Tom
> 
> 
> On Wed, Nov 1, 2017 at 10:54 AM, Derek Atkins <warlord at mit.edu> wrote:
> 
> > Tom,
> >
> > Tom Luo <mariolzx at gmail.com> writes:
> >
> > > Yes. I want only one IP gets access to the service. However, I don't own
> > > this application and I don't have the source code. That is why I can only
> > > using firewall to handle it.
> > > If there is no software capable to handle this, I am thinking about
> > writing
> > > a shell script to do it myself.
> >
> > Just so I understand:   You have a service running on a server which
> > *anyone* can use.  But once *someone* is using it, further connections
> > can only come from that single IP address.   And then, once all
> > connections drop again (i.e., nobody is using the service), then it
> > opens up to anyone on any IP address again until someone else connects?
> >
> > Do I have this right?
> >
> > If so, I'm honestly not sure how to do this outside the application
> > itself.  You MIGHT be able to do it with tcp_wrappers with some state on
> > the machine for the number of open connections.
> >
> > Another option is that you MIGHT be able to do this with something like
> > fail2ban + firewalld.  Every time there is a first-time connection then
> > you add a firewall rule that limits access to only that IP address, and
> > then once the user "logs out" you remove that restriction.  Of course
> > you would need to ensure that the connection/disconnection get logged
> > properly, and you'd need to write the fail2ban scripts.
> >
> > If you cannot modify the application itself then this might be
> > challenging to get all the connect/disconnect messages to properly line
> > up.
> >
> > > Thanks,
> >
> > -derek
> >
> > --
> >        Derek Atkins, SB '93 MIT EE, SM '95 MIT Media Laboratory
> >        Member, MIT Student Information Processing Board  (SIPB)
> >        URL: http://web.mit.edu/warlord/    PP-ASEL-IA     N1NWH
> >        warlord at MIT.EDU                        PGP key available
> >
> _______________________________________________
> Discuss mailing list
> Discuss at blu.org
> http://lists.blu.org/mailman/listinfo/discuss