grant internet access to centos 8 VMs in vmware workstation

mehdi2020 · 11-19-2022, 04:15 PM

Hi,

i have connected 4 centos8 VMs to 192.168.1.0/24 using LAN segment option in vmware.

i picked 192.168.1.1 VM and i added another network adapter using NAT option.

i gave all the 3 other VMs the ip addr : 192.168.1.1 as a gateway.

i can reach the internet on 192.168.1.1, but the other 3 VMs could not !, can you help me ? thank you.

wpeckham · 11-19-2022, 07:14 PM

Did you configure 192.168.1.1 as a routing or forwarding device?

That does not happen by magic, someone has to set it up.

mehdi2020 · 11-20-2022, 02:35 AM

Quote:

Originally Posted by wpeckham

Did you configure 192.168.1.1 as a routing or forwarding device?

That does not happen by magic, someone has to set it up.

yes, i have : net.ipv4.ip_forward = 1, in /etc/sysctl.conf of 192.168.1.1, but still the 3 VMs don't connect to internet.

mehdi2020 · 11-20-2022, 02:37 AM

yes, i have : net.ipv4.ip_forward = 1, in /etc/sysctl.conf of 192.168.1.1, but still the 3 VMs don't connect to the internet.

michaelk · 11-20-2022, 06:28 PM

If the output of the command is zero i.e.
cat /proc/sys/net/ipv4/ip_forward
0

Then IP forwarding is disabled. To enable IP forwarding use the following command.
echo 1 > /proc/sys/net/ipv4/ip_forward

Editing the file should enable forwarding when the vm starts.

mehdi2020 · 11-21-2022, 11:07 AM

the output is : 1, the VMs do ping each other locally (LAN), but they can't access the internet.

wpeckham · 11-21-2022, 11:48 AM

Quote:

Originally Posted by mehdi2020

the output is : 1, the VMs do ping each other locally (LAN), but they can't access the internet.

Good first step. Now, can the nodes all ping 192.168.1.1 and get a success return?
If that fails, we have our issue identified. If not, we will need more steps. Troubleshooting is rarely a one step to answer process.

mehdi2020 · 11-21-2022, 02:27 PM

yes, they ping 192.168.1.1

wpeckham · 11-21-2022, 06:12 PM

And I presume 192.168.1.1 can ping the nodes successfully. (Correct me if that is wrong.)

Is there a firewall running either on the host, or on 192.168.1.1, or on any of the nodes?

Can yo do packet tracing and log the packets?

mehdi2020 · 11-22-2022, 08:20 AM

yes, that's the prblm : firewall; i fixed this issue with the command : iptables -t nat -A POSTROUTING -o ens160 -j MASQUERADE. thank you.

but now : the 3 VMs do ping 8.8.8.8, but they can't resolve domain name, i get this message when i try to do update or sth else :

Curl error (6): Couldn't resolve host name for http://mirrorlist.centos.org/?releas...am&infra=stock [Could not resolve host: mirrorlist.centos.org]

can you help me again. thank you.

michaelk · 11-22-2022, 08:43 AM

Did you configure DNS for the VMs?

mehdi2020 · 11-22-2022, 09:18 AM

yes, i configured 8.8.8.8 in the DNS for the VMs, but still they can't resolve domain name.

wpeckham · 11-22-2022, 10:07 AM

Do they all have the same /etc/resolv.conf?
What does the /etc/resolv.conf look like on those nodes?

michaelk · 11-22-2022, 11:43 AM

Are you using network manager?
How did you configure dns on the vms?

mehdi2020 · 11-22-2022, 12:41 PM

this is what i have in /etc/resolv.conf :

# Generated by NetworkManager
nameserver 8.8.8.8