I have from my isp a static ip X.X.X.X and an unrouted public subnet Y.Y.Y.0/24 registred at ripe.

An ex-coworker of mine setup a server that does the routing which have te folowing config:

  ISP------->(eth0) Server (eth1)--->Switch---> Multiple pc
X.X.X.X       eth0   : X.X.X.X            Static ip: Y.Y.Y.100-150 (each pc have its own public ip)
              eth1:2 : Y.Y.Y.1            Gateway  : Y.Y.Y.1
              eth1:3 : Y.Y.Y.2                                   
              eth1:4 : Y.Y.Y.3                                   

Once I changed my plan to 10Gpbs (Internet in Romania is dirt cheap) the server was deprecated so we bougnt a new capable one. I can't find on internet how to setup the new one to do exactly the same thing as the old one.... Most of the ISPs route the subnet themselves but mine doesn't. When I called my ISP for help their answer was: "Deal with it! Search on google !"

  • If the /24 is actually allocated to you in RIPE then your ISP should be able to just statically route it to you. If your contact at the ISP doesn't know what this means then escalate to a higher support tier. You don't need an ASN or BGP if you're not planning to connect to multiple ISP's. – rnxrx Jan 9 '17 at 3:03
  • Did any answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you could provide and accept your own answer. – Ron Maupin Aug 15 '17 at 17:44

You will need to run BGP with your ISP. BGP will advertise your prefix(es) to the ISP, and vice versa. If you only have one ISP, the you could negotiate for the ISP to only send a default route, or ignore what your ISP sends you in favor of a default route. You will need to get your own AS number unless your ISP will let you use a private AS number.

You probably don't want to do this with a server. Use a real router. If you insist on using a server, then you should ask this question on Server Fault instead of here.

  • The ASN is AS8708 (The ISP). I don't have a private AS. Could you recomand me a router? – Nicolescu Vlad Jan 7 '17 at 21:39
  • Unfortunately, product or resource recommendations are explicitly off-topic here. You will need an AS to communicate with the ISP AS. It sounds like you have provider-independent IPv4 addressing, so it does not belong to your ISP. Some ISPs, under some circumstances, will let you use private AS numbers, but you should really have your own AS number if you have your own prefix(es). – Ron Maupin Jan 7 '17 at 21:43
  • and how do i get my own AS number? The ISP registred the IP class in our name. On ripe side I am the owner of the /24 but my AS is same as my ISP's. – Nicolescu Vlad Jan 7 '17 at 21:45
  • IANA allocates AS number to the RIRs for assignment, the same way that IP networks are allocated and assigned. You get it from your RIR. – Ron Maupin Jan 7 '17 at 21:48

You can use a free firewall solution that can do great things on your scenario. Like you said, sever is 10 Gb capable, then get the software and install it. With that you will have a router, if you need it, and the main thing, a firewall. Put the IP on your WAN interface, and the same on your LAN interface. At this point, you need t create a static route across your WAN link: 0.0.0 next-hop(ip_of_your_isp)

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