AWS routing question



  • @IRJ said in AWS routing question:

    @Dashrender said in AWS routing question:

    Do I understand this correctly? you have a subnet with two different IP ranges on it - one being a public IP, and the other being private?

    Whatever device is acting as the router for that subnet would need to understand how to route both of those networks to make that work.

    And now for the patented @JaredBusch FFS moment.

    No that is not how it works. The Public IPs are attached to NIC not the subnet.

    Aww - I see how I misread the post.

    The firewall is (I'm assuming) NATing 1:1 for the original server to a real IP, but that server itself has an internal IP for the internal subnet?

    You could setup another IP on the firewall that the rest of the traffic flows out from on a many:1 setup.



  • @JaredBusch said in AWS routing question:

    @IRJ said in AWS routing question:

    @JaredBusch said in AWS routing question:

    @IRJ said in AWS routing question:

    @JaredBusch said in AWS routing question:

    @IRJ is the server with a public IP running a router?

    Nope

    Then that is your problem. It has no idea what to do with these requests coming in from the other machine.

    Yeah so I am guessing I am better off just putting this box on a new subnet all together.

    What you want to do is entirely possible. Just the device with the public IP needs to be setup to route traffic.

    What I really want to do which I dont know if this is possible is route any requests from it's IP to the NAT instead of internet gateway.



  • If the router device as JB said, isn't doing a 1:1 NAT for the original server, than yeah, you could use that same IP outbound for everything on the network, you just need to configure for that setup.



  • @IRJ said in AWS routing question:

    @JaredBusch said in AWS routing question:

    @IRJ said in AWS routing question:

    @JaredBusch said in AWS routing question:

    @IRJ said in AWS routing question:

    @JaredBusch said in AWS routing question:

    @IRJ is the server with a public IP running a router?

    Nope

    Then that is your problem. It has no idea what to do with these requests coming in from the other machine.

    Yeah so I am guessing I am better off just putting this box on a new subnet all together.

    What you want to do is entirely possible. Just the device with the public IP needs to be setup to route traffic.

    What I really want to do which I dont know if this is possible is route any requests from it's IP to the NAT instead of internet gateway.

    You want Server A (with public & private) to talk only to Server B (private only)?



  • @Dashrender said in AWS routing question:

    @IRJ said in AWS routing question:

    @Dashrender said in AWS routing question:

    Do I understand this correctly? you have a subnet with two different IP ranges on it - one being a public IP, and the other being private?

    Whatever device is acting as the router for that subnet would need to understand how to route both of those networks to make that work.

    And now for the patented @JaredBusch FFS moment.

    No that is not how it works. The Public IPs are attached to NIC not the subnet.

    Aww - I see how I misread the post.

    The firewall is (I'm assuming) NATing 1:1 for the original server to a real IP, but that server itself has an internal IP for the internal subnet?

    You could setup another IP on the firewall that the rest of the traffic flows out from on a many:1 setup.

    Yeah so any traffic not destined for 10.x.x.x is going through an internet gateway which connects through public IP.



  • @JaredBusch said in AWS routing question:

    @IRJ said in AWS routing question:

    @JaredBusch said in AWS routing question:

    @IRJ said in AWS routing question:

    @JaredBusch said in AWS routing question:

    @IRJ said in AWS routing question:

    @JaredBusch said in AWS routing question:

    @IRJ is the server with a public IP running a router?

    Nope

    Then that is your problem. It has no idea what to do with these requests coming in from the other machine.

    Yeah so I am guessing I am better off just putting this box on a new subnet all together.

    What you want to do is entirely possible. Just the device with the public IP needs to be setup to route traffic.

    What I really want to do which I dont know if this is possible is route any requests from it's IP to the NAT instead of internet gateway.

    You want Server A (with public & private) to talk only to Server B (private only)?

    Yes and then I went server B to go out to the internet through the NAT device. I dont want it dependent on Server A in anyway.



  • @IRJ said in AWS routing question:

    @JaredBusch said in AWS routing question:

    @IRJ said in AWS routing question:

    @JaredBusch said in AWS routing question:

    @IRJ said in AWS routing question:

    @JaredBusch said in AWS routing question:

    @IRJ said in AWS routing question:

    @JaredBusch said in AWS routing question:

    @IRJ is the server with a public IP running a router?

    Nope

    Then that is your problem. It has no idea what to do with these requests coming in from the other machine.

    Yeah so I am guessing I am better off just putting this box on a new subnet all together.

    What you want to do is entirely possible. Just the device with the public IP needs to be setup to route traffic.

    What I really want to do which I dont know if this is possible is route any requests from it's IP to the NAT instead of internet gateway.

    You want Server A (with public & private) to talk only to Server B (private only)?

    Yes and then I went server B to go out to the internet through the NAT device. I dont want it dependent on Server A in anyway.

    If Server A has no public NIC, then it has to talk to a NAT router someplace. You only have Server A and Server B. So where is the NAT happening?



  • This post is deleted!


  • @JaredBusch said in AWS routing question:

    @IRJ said in AWS routing question:

    @JaredBusch said in AWS routing question:

    @IRJ said in AWS routing question:

    @JaredBusch said in AWS routing question:

    @IRJ said in AWS routing question:

    @JaredBusch said in AWS routing question:

    @IRJ said in AWS routing question:

    @JaredBusch said in AWS routing question:

    @IRJ is the server with a public IP running a router?

    Nope

    Then that is your problem. It has no idea what to do with these requests coming in from the other machine.

    Yeah so I am guessing I am better off just putting this box on a new subnet all together.

    What you want to do is entirely possible. Just the device with the public IP needs to be setup to route traffic.

    What I really want to do which I dont know if this is possible is route any requests from it's IP to the NAT instead of internet gateway.

    You want Server A (with public & private) to talk only to Server B (private only)?

    Yes and then I went server B to go out to the internet through the NAT device. I dont want it dependent on Server A in anyway.

    If Server A has no public NIC, then it has to talk to a NAT router someplace. You only have Server A and Server B. So where is the NAT happening?

    Right - I'm trying to see if you have a multi-homed machine (i.e. two NICs - one plugged into internet, and one plugged into internal subnet)? or do you have two IPs assigned to the same NIC in Server A?



  • @Dashrender said in AWS routing question:

    @JaredBusch said in AWS routing question:

    @IRJ said in AWS routing question:

    @JaredBusch said in AWS routing question:

    @IRJ said in AWS routing question:

    @JaredBusch said in AWS routing question:

    @IRJ said in AWS routing question:

    @JaredBusch said in AWS routing question:

    @IRJ said in AWS routing question:

    @JaredBusch said in AWS routing question:

    @IRJ is the server with a public IP running a router?

    Nope

    Then that is your problem. It has no idea what to do with these requests coming in from the other machine.

    Yeah so I am guessing I am better off just putting this box on a new subnet all together.

    What you want to do is entirely possible. Just the device with the public IP needs to be setup to route traffic.

    What I really want to do which I dont know if this is possible is route any requests from it's IP to the NAT instead of internet gateway.

    You want Server A (with public & private) to talk only to Server B (private only)?

    Yes and then I went server B to go out to the internet through the NAT device. I dont want it dependent on Server A in anyway.

    If Server A has no public NIC, then it has to talk to a NAT router someplace. You only have Server A and Server B. So where is the NAT happening?

    Right - I'm trying to see if you have a multi-homed machine (i.e. two NICs - one plugged into internet, and one plugged into internal subnet)? or do you have two IPs assigned to the same NIC in Server A?

    One NIC with two assigned IPs



  • @IRJ said in AWS routing question:

    @Dashrender said in AWS routing question:

    @JaredBusch said in AWS routing question:

    @IRJ said in AWS routing question:

    @JaredBusch said in AWS routing question:

    @IRJ said in AWS routing question:

    @JaredBusch said in AWS routing question:

    @IRJ said in AWS routing question:

    @JaredBusch said in AWS routing question:

    @IRJ said in AWS routing question:

    @JaredBusch said in AWS routing question:

    @IRJ is the server with a public IP running a router?

    Nope

    Then that is your problem. It has no idea what to do with these requests coming in from the other machine.

    Yeah so I am guessing I am better off just putting this box on a new subnet all together.

    What you want to do is entirely possible. Just the device with the public IP needs to be setup to route traffic.

    What I really want to do which I dont know if this is possible is route any requests from it's IP to the NAT instead of internet gateway.

    You want Server A (with public & private) to talk only to Server B (private only)?

    Yes and then I went server B to go out to the internet through the NAT device. I dont want it dependent on Server A in anyway.

    If Server A has no public NIC, then it has to talk to a NAT router someplace. You only have Server A and Server B. So where is the NAT happening?

    Right - I'm trying to see if you have a multi-homed machine (i.e. two NICs - one plugged into internet, and one plugged into internal subnet)? or do you have two IPs assigned to the same NIC in Server A?

    One NIC with two assigned IPs

    So the router that's on that 'subnet' is only aware of the Public IP range info, I'm guessing - right? The router doesn't know about 10.x.x.x, even though that data is on the wire. You'd need to make the router also One NIC with two IPs.. then setup NAT routing out.



  • Thanks @JaredBusch for reminding me to look at the OP - this is AWS.... so ...



  • Subnet 1 - Routes out to the Internet though Internet Gateway
    Subnet 2 - Rotues to the internet through NAT on subnet1
    Subnet 3 - Rotues to the internet through NAT on subnet1
    Subnet 4 - Rotues to the internet through NAT on subnet1
    Subnet 5 - Rotues to the internet through NAT on subnet1
    Subnet 6 - Rotues to the internet through NAT on subnet1
    Subnet 7 - Rotues to the internet through NAT on subnet1

    What I am trying to do is route a single server on Subnet 1 through the NAT as well. The route table is controlled at Subnet level. So If I change the subnet routeing rules to go through NAT it breaks.



  • I know nothing about AWS routing - can you setup two IPs on the Subnet 1 "router" interface. I know it's not a real router - it's all in software, but I don't know what else to call it.



  • @Dashrender said in AWS routing question:

    I know nothing about AWS routing - can you setup two IPs on the Subnet 1 "router" interface. I know it's not a real router - it's all in software, but I don't know what else to call it.

    Devices are not configurable. Both NAT and IGW have zero configurable options. You just create them in AWS



  • You need to setup the EC2 instance with a WAN Dynamic IP (Elastic IP address). Then just go through the Internet gateway and have the security group blocking incoming traffic over the Dynamic IP provided to the EC2 instance.


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