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Confused about the router IPs, help appreciated

leveller
Aspirant

Confused about the router IPs, help appreciated

I have the DGND3700v1. IPs below not the actual ones.

It has the IP 192.168.0.1 assigned to it and it uses DHCP to auto assign IPs to the LAN.

It has an external IP assigned by the ISP 86.126.24.57 and when I visit a site which shows my IP this is the one shown to the outside world.

The confusing part is my Gateway IP Address, which I assumed was something to do with NAT. This has IP 187.38.123.98. This IP is neither revealed by visiting sites nor revealed on the LAN. However, if I do a TRACERT the results are as follows:

freetrace to www.bbc.co.uk, 64 hops max, 52 byte packets

*hop(1) 92 bytes *192.168.0.1
*hop(2) 36 bytes *lns15.inx.dsl.enta.net (187.38.123.98) my gateway IP address
*hop(3) 36 bytes *gi1-5.inx.dist.dsl.enta.net (187.38.123.97) my gateway IP address minus 1
*hop(4) 36 bytes *te2-2.interxion.dsl.enta.net (78.33.141.89)
*hop(5) 36 bytes *te2-3.interxion.core.enta.net (86.126.236.209)
*hop(6) 36 bytes *te4-2.telehouse-east.core.enta.net (86.126.236.137)
*hop(7) 36 bytes *bbc-gw0-linx.prt0.thdoe.bbc.co.uk (195.66.224.103)
*hop(8) ******************** *Request timeout
*hop(9) ******************** *Request timeout
*hop(10) 36 bytes *ae0.er01.telhc.bbc.co.uk (132.185.254.109)
*hop(11) 36 bytes *132.185.255.148
*hop(12) 64 bytes *212.58.244.68

*----- END TRACE ------

Surely if my Gateway IP Address is my NAT address then it shouldn't show in a TRACERT, and why am I hopping to another IP with the same IP minus 1 in the last octet?!?!
Message 1 of 4
leveller
Aspirant

Re: Confused about the router IPs, help appreciated

Ah, I think I'm being too literal in my thinking.

The reason why I'm looking into the network features is because recently I had some fluctuations in network activity which has been dropping me from online games. I check the firewall logs and see DOS Storm and another type of DOS activity. And now I'm seeing regular ICMP ECHO REQ, message type b and another type, service blocked, packet dropped, packet allowed, packet accepted.

Am I right in thinking the Gateway IP Address is the address given by my ISP as the one my router should connect to when I want to use my broadband? Rather than what I originally thought was something to do with NAT. I guess NAT stays hidden.

So, a packet from this computer goes:

To 192.168.0.1
Then through NAT
Then through my external IP assigned by ISP 86.126.24.57
To Gateway IP Address which is my ISP 1st hop, 187.38.123.98
Then onwards ...

Correct?
Message 2 of 4
albgen
Aspirant

Re: Confused about the router IPs, help appreciated

well it's correct that you see 192.168.0.1
This is the gateway for the devices connected on your router.
Message 3 of 4
Dick_W
Aspirant

Re: Confused about the router IPs, help appreciated

leveller wrote:
Am I right in thinking the Gateway IP Address is the address given by my ISP as the one my router should connect to when I want to use my broadband? Rather than what I originally thought was something to do with NAT. I guess NAT stays hidden.

So, a packet from this computer goes:

To 192.168.0.1
Then through NAT
Then through my external IP assigned by ISP 86.126.24.57
To Gateway IP Address which is my ISP 1st hop, 187.38.123.98
Then onwards ...

Correct?


Correct twice. NAT is not an address in and of itself, it is a translation table maintained in the router between local net address (192.168.0.2, say) and a given connection (BBC.co.UK port 80--http) for that connection that is translated to the local router's "real" IP address. With this, the router knows where to send the response when it gets it.

The router's assigned gateway address is nothing more than where it sends a packet it doesn't know how to route to a destination on its own. That's at the core of how IP works.
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