What stops someone from configuring their network with IP addresses they do not own?












2















Here's the scenario. I was picturing a university that bought a range of IP addresses. I think they'd still be inside a ISP (right?), but they'd have freedom to configure stuff the way they wanted.



What stops them from attributing their routers and hosts already in use IP addresses?



And what would happen if indeed someone do this?










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    2















    Here's the scenario. I was picturing a university that bought a range of IP addresses. I think they'd still be inside a ISP (right?), but they'd have freedom to configure stuff the way they wanted.



    What stops them from attributing their routers and hosts already in use IP addresses?



    And what would happen if indeed someone do this?










    share|improve this question









    New contributor




    Tiago Oliveira is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.























      2












      2








      2








      Here's the scenario. I was picturing a university that bought a range of IP addresses. I think they'd still be inside a ISP (right?), but they'd have freedom to configure stuff the way they wanted.



      What stops them from attributing their routers and hosts already in use IP addresses?



      And what would happen if indeed someone do this?










      share|improve this question









      New contributor




      Tiago Oliveira is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.












      Here's the scenario. I was picturing a university that bought a range of IP addresses. I think they'd still be inside a ISP (right?), but they'd have freedom to configure stuff the way they wanted.



      What stops them from attributing their routers and hosts already in use IP addresses?



      And what would happen if indeed someone do this?







      router ip network internet ip-address






      share|improve this question









      New contributor




      Tiago Oliveira is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.











      share|improve this question









      New contributor




      Tiago Oliveira is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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      share|improve this question




      share|improve this question








      edited 3 hours ago







      Tiago Oliveira













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      asked 4 hours ago









      Tiago OliveiraTiago Oliveira

      7415




      7415




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      New contributor





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      Check out our Code of Conduct.






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          2 Answers
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          Most likely if they're a big university they are their own ISP, using BGP to connect their network to the internet via a number of upstream networks.



          Nothing stops them from using IP addresses they should not be using, and it would work in their local network. However, it won't work on the internet. Their upstream networks providing them connectivity should have filters in place which would only allow the university to advertise IP addresses assigned to them. If the direct upstreams wouldn't filter them, the upstreams' upstreams will. And if IP addresses which are in use by another network would be used by the university, that other network would become unreachable from the university network.



          In addition, there are a number of project (for example RIPE RIS and BGPmon) which monitor routing tables and alert on any "illegal" IP advertisement (BGP Hijacks and routing anomalies).






          share|improve this answer































            1














            Nothing will stop them using the addresses on their own machines.



            What happens if they try to advertise them to the Internet depends on how sloppy their providers are. If their providers are following best practices then there will be filters in place and the advertisements won't get beyond the hijacker's borders.



            OTOH if their providers and their providers providers are sloppy then a bogus announcement can go much further resulting in significant disruption to the legitimate owners of the IP space.



            Such happenings will almost certainly get noticed and there will likely be some heated discussions and some extra filtering added.






            share|improve this answer























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              2 Answers
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              active

              oldest

              votes








              2 Answers
              2






              active

              oldest

              votes









              active

              oldest

              votes






              active

              oldest

              votes









              3














              Most likely if they're a big university they are their own ISP, using BGP to connect their network to the internet via a number of upstream networks.



              Nothing stops them from using IP addresses they should not be using, and it would work in their local network. However, it won't work on the internet. Their upstream networks providing them connectivity should have filters in place which would only allow the university to advertise IP addresses assigned to them. If the direct upstreams wouldn't filter them, the upstreams' upstreams will. And if IP addresses which are in use by another network would be used by the university, that other network would become unreachable from the university network.



              In addition, there are a number of project (for example RIPE RIS and BGPmon) which monitor routing tables and alert on any "illegal" IP advertisement (BGP Hijacks and routing anomalies).






              share|improve this answer




























                3














                Most likely if they're a big university they are their own ISP, using BGP to connect their network to the internet via a number of upstream networks.



                Nothing stops them from using IP addresses they should not be using, and it would work in their local network. However, it won't work on the internet. Their upstream networks providing them connectivity should have filters in place which would only allow the university to advertise IP addresses assigned to them. If the direct upstreams wouldn't filter them, the upstreams' upstreams will. And if IP addresses which are in use by another network would be used by the university, that other network would become unreachable from the university network.



                In addition, there are a number of project (for example RIPE RIS and BGPmon) which monitor routing tables and alert on any "illegal" IP advertisement (BGP Hijacks and routing anomalies).






                share|improve this answer


























                  3












                  3








                  3







                  Most likely if they're a big university they are their own ISP, using BGP to connect their network to the internet via a number of upstream networks.



                  Nothing stops them from using IP addresses they should not be using, and it would work in their local network. However, it won't work on the internet. Their upstream networks providing them connectivity should have filters in place which would only allow the university to advertise IP addresses assigned to them. If the direct upstreams wouldn't filter them, the upstreams' upstreams will. And if IP addresses which are in use by another network would be used by the university, that other network would become unreachable from the university network.



                  In addition, there are a number of project (for example RIPE RIS and BGPmon) which monitor routing tables and alert on any "illegal" IP advertisement (BGP Hijacks and routing anomalies).






                  share|improve this answer













                  Most likely if they're a big university they are their own ISP, using BGP to connect their network to the internet via a number of upstream networks.



                  Nothing stops them from using IP addresses they should not be using, and it would work in their local network. However, it won't work on the internet. Their upstream networks providing them connectivity should have filters in place which would only allow the university to advertise IP addresses assigned to them. If the direct upstreams wouldn't filter them, the upstreams' upstreams will. And if IP addresses which are in use by another network would be used by the university, that other network would become unreachable from the university network.



                  In addition, there are a number of project (for example RIPE RIS and BGPmon) which monitor routing tables and alert on any "illegal" IP advertisement (BGP Hijacks and routing anomalies).







                  share|improve this answer












                  share|improve this answer



                  share|improve this answer










                  answered 4 hours ago









                  Teun VinkTeun Vink

                  11k52751




                  11k52751























                      1














                      Nothing will stop them using the addresses on their own machines.



                      What happens if they try to advertise them to the Internet depends on how sloppy their providers are. If their providers are following best practices then there will be filters in place and the advertisements won't get beyond the hijacker's borders.



                      OTOH if their providers and their providers providers are sloppy then a bogus announcement can go much further resulting in significant disruption to the legitimate owners of the IP space.



                      Such happenings will almost certainly get noticed and there will likely be some heated discussions and some extra filtering added.






                      share|improve this answer




























                        1














                        Nothing will stop them using the addresses on their own machines.



                        What happens if they try to advertise them to the Internet depends on how sloppy their providers are. If their providers are following best practices then there will be filters in place and the advertisements won't get beyond the hijacker's borders.



                        OTOH if their providers and their providers providers are sloppy then a bogus announcement can go much further resulting in significant disruption to the legitimate owners of the IP space.



                        Such happenings will almost certainly get noticed and there will likely be some heated discussions and some extra filtering added.






                        share|improve this answer


























                          1












                          1








                          1







                          Nothing will stop them using the addresses on their own machines.



                          What happens if they try to advertise them to the Internet depends on how sloppy their providers are. If their providers are following best practices then there will be filters in place and the advertisements won't get beyond the hijacker's borders.



                          OTOH if their providers and their providers providers are sloppy then a bogus announcement can go much further resulting in significant disruption to the legitimate owners of the IP space.



                          Such happenings will almost certainly get noticed and there will likely be some heated discussions and some extra filtering added.






                          share|improve this answer













                          Nothing will stop them using the addresses on their own machines.



                          What happens if they try to advertise them to the Internet depends on how sloppy their providers are. If their providers are following best practices then there will be filters in place and the advertisements won't get beyond the hijacker's borders.



                          OTOH if their providers and their providers providers are sloppy then a bogus announcement can go much further resulting in significant disruption to the legitimate owners of the IP space.



                          Such happenings will almost certainly get noticed and there will likely be some heated discussions and some extra filtering added.







                          share|improve this answer












                          share|improve this answer



                          share|improve this answer










                          answered 1 hour ago









                          Peter GreenPeter Green

                          7,47621226




                          7,47621226






















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