Need to configure NAT on c3745 router - Page 2

double-happiness · ‎05-13-2022

Topology: https://i.imgur.com/a1azOy0.jpg

R1#show run
Building configuration...

Current configuration : 1269 bytes
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname R1
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
no ip icmp rate-limit unreachable
ip cef
!
!
!
!
ip name-server 8.8.8.8
!
multilink bundle-name authenticated
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
archive
log config
hidekeys
!
!
!
!
ip tcp synwait-time 5
!
!
!
!
interface FastEthernet0/0
ip address 192.168.0.1 255.255.255.0
ip nat inside
ip virtual-reassembly
duplex auto
speed auto
!
interface FastEthernet0/1
ip address 172.16.0.1 255.255.255.0
ip nat inside
ip virtual-reassembly
duplex auto
speed auto
!
interface FastEthernet1/0
ip address 192.168.1.121 255.255.255.0
ip nat outside
ip virtual-reassembly
duplex auto
speed auto
!
ip forward-protocol nd
ip route 0.0.0.0 0.0.0.0 192.168.1.1
!
!
no ip http server
no ip http secure-server
ip nat inside source list 10 interface FastEthernet1/0 overload
!
access-list 10 permit 0.0.0.0
no cdp log mismatch duplex
!
!
!
!
!
!
control-plane
!
!
!
!
!
!
!
!
!
!
line con 0
exec-timeout 0 0
privilege level 15
logging synchronous
line aux 0
exec-timeout 0 0
privilege level 15
logging synchronous
line vty 0 4
login
!
!
end

Network config for the VM:

network:
version: 2
renderer: networkd
ethernets:
enp0s3:
addresses:
- 192.168.0.3/24
gateway4: 192.168.0.1
nameservers:
search: [mydomain, otherdomain]
addresses: [8.8.8.8, 8.8.4.4]

Wireshark capture: https://i.imgur.com/7zruy6a.jpg

Someone told me this on another forum yesterday:

> Does the "cloud" have a route back to 192.168.0.0/24? [...] If you didn't put it there, the answer is no. So that's your problem. The return traffic has no route to your VM.

I was reading https://networklessons.com/cisco/ccie-routing-switching/ip-nat-inside-source-vs-ip-nat-outside-source and wonder if I need to do...

R1(config)#ip nat inside source static 192.168.0.1 192.168.1.121
R1(config)#ip nat inside source static 172.16.0.1 192.168.1.121

Is that correct?

Flavio Miranda · ‎05-13-2022

Do it from router.

double-happiness · ‎05-13-2022

Oh, right. Well, that comes back:

Tracing the route to dns.google (8.8.8.8)

1 192.168.1.1 72 msec 72 msec 72 msec
2 ae50-ner001.msp.as13285.net (78.144.1.33) 108 msec 112 msec 112 msec
3 ae50-scr001-msp.as13285.net (78.144.1.32) 104 msec 80 msec 76 msec
4 ae63-scr102.thw.as13285.net (78.144.1.128) 72 msec 108 msec 108 msec
5 74.125.51.108 108 msec 72 msec
74.125.51.110 68 msec
6 * * *
7 dns.google (8.8.8.8) 56 msec 120 msec
172.253.65.210 96 msec

I hope I have made it clear that I can ping 8.8.8.8 fine from the router though? It was only the VMs that are having any issues connecting to the web when I made my post. In fact, compared to this guide https://docs.gns3.com/docs/using-gns3/advanced/connect-gns3-internet/ I can do all that. Like I said, I can even ping Google from the router, but not from the VMs.

Edit: this is a Wireshark capture, where 192.168.0.2 is one of my VMs

Flavio Miranda · ‎05-13-2022

From the network perspective I believe this is it. The packet from Lab machine should go to the router, the router should send it to your physical machine, then to internet and return. All it set for that.

Try to replace the Linux VM for a router and see the result.

And nop, I did not realize that from router you were able to ping on the internet since the begining You start this post asking about NAT.

double-happiness · ‎05-13-2022

2/ Actually, I was able to run traceroute from my Observium VM. It just comes back...

192.168.0.1 (192.168.0.1) [and so on...]

For the first hop, and that's it, no other IPs shown. And that it is with the firewall right off.

Flavio Miranda · ‎05-13-2022

You need to add a route on the router like

ip route 0.0.0.0 0.0.0.0 "Physical Machine Ip address "

double-happiness · ‎05-13-2022

I thought I had that already though? That's 192.168.1.1 isn't it?

On the GNS3 router:

Gateway of last resort is 192.168.1.1 to network 0.0.0.0

172.16.0.0/24 is subnetted, 1 subnets
C 172.16.0.0 is directly connected, FastEthernet0/1
C 192.168.0.0/24 is directly connected, FastEthernet0/0
C 192.168.1.0/24 is directly connected, FastEthernet1/0
S* 0.0.0.0/0 [1/0] via 192.168.1.1

Flavio Miranda · ‎05-13-2022

I think it is not right. You are using your home router as the Lab Router´s gateway? If so, you need to use your machine as your Lab gateway. Your home router does not know your Lab network so it can not reply back. Unless you can add routes on your home router. That´s why you added static routes on your windows machine.

double-happiness · ‎05-13-2022

> You are using your home router as the Lab Router´s gateway?

I think I originally tried to set the lab router's gateway to 192.168.1.121, but that didn't work, because it said something like 'invalid next hop - it's this router!'

I really don't know what to do next, to be honest. But it seems like you are saying to delete the static routes from the lab router and set them up on my home router instead, I suppose.

To be quite honest, I'm really tired and demoralised by all this. I've been working on this for 21 days from start to finish now, and when I saw pings come back from the router, I thought I was nearly there. But it seems like actually I was still nowhere near succeeding.

Flavio Miranda · ‎05-13-2022

I think it is not right. You are using your home router as the Lab Router´s gateway? If so, you need to use your machine as your Lab gateway. Your home router does not know your Lab network so it can not reply back. Unless you can add routes on your home router. That´s why you added static routes on your windows machine.

S* 0.0.0.0/0 [1/0] via 192.168.1.1 (It is your home router??)

S* 0.0.0.0/0 [1/0] via (Your physical machine)

double-happiness · ‎05-13-2022

> S* 0.0.0.0/0 [1/0] via 192.168.1.1 (It is your home router??)

Yes, that is my home router.

Flavio Miranda · ‎05-13-2022

Do as I said please.

The virtual machine send to lab router....Lab router to your machine and not to your home router.

Follow the draw above.

double-happiness · ‎05-13-2022

Ah right, I think maybe I have got you now; hope so anyway.

S* 0.0.0.0/0 [1/0] via 192.168.1.1

...should read...

S* 0.0.0.0/0 [1/0] via 192.168.1.11

Is that correct please??

Flavio Miranda · ‎05-13-2022

Yes.

You windows machine need to be the gateway as it has ´ "Physical" contact with the Lab and it has the static routes do the LAB and access to the internet too.

double-happiness · ‎05-13-2022

OK, well I tried that, but now I can't ping 8.8.8.8 from the router, I can only ping the physical router, and the VM isn't getting any pings back except 192.168.0.1.

Edit: I don't understand what has happened to those routes I thought I added before for 192.168.0.1 and 172.16.0.1?? Where have they gone??

Flavio Miranda · ‎05-13-2022

did you reload the PC?

add them again. They need to be in place to work