Hello,
I want to install a SSL certificate on my website but i get this error :
Unable to find a virtual host listening on port 80 which is currently needed for Certbot to prove to the CA that you control your domain. Please add a virtual host for port 80.
My apache server is listening on the port 71. Can I stil install the SSL certificate on my website ?
Thank you in advance.
Authentication must be over port 80.
If you are unable to (also) listen on port 80, you may have to use DNS authentication to obtain the cert - which can be used on any port thereafter.
Thank you @rg305 ,
Can I change temporarily the port on 80 to install the certificate and then reset to my original configuration ?
If your ISP is not blocking port 80 inbound, yes, that should work.
And port 80 is not already being used by anything else…
In fact my apache server is connected to a VPS with a VPN ( the VPS is hosting the VPN server) so the port 80 is already used and I have to use the port 71 instead to acess to my website.
I have no solution ? 
Yes, you do: use DNS validation, as @rg305 mentioned above.
Hi @C9H13N
check the command line options:
https://certbot.eff.org/docs/using.html
sudo ./certbot --preferred-challenges dns-01
may be enough to start. You have to create a new dns text entry
_acme-challenge.yourdomain.com
with a special value. But if you want to renew the certificate, you have to set a new value.
Yes I think it will solved my problem. But when I run this command I have the following error :
None of the preferred challenges are supported by the selected plugin
I can’t find the command to install the “dns plugin” 
If you want to use the dns-01 - validation and if your dns provider doesn’t support an api, you have to use
--manual
as authenticator. But I don’t know if you install your certificate manual or automatic.
Perhaps you use
certonly
as additional option and install the certificate manual.
I don’t know how certbot handles such a configuration where no standard port 80 is open.
Yep thanks, I have now installed the certificate.
Congratulations! Your certificate and chain have been saved at: /etc/letsencrypt/live/technet.ovh/fullchain.pem
Actually it should work but for some reason I can’t acess to : https://www.technet.ovh
If you use certonly, you have to install the certificate manual.
And: Which port does your installation use? Port 443? Or another port?
Your http works. But http doesn't answer. Check your firewall.
The traffic is going through different port and 2 different VPN … Now I think I can solve the problem alone.
Thanks a lot @JuergenAuer
Good to know - thanks.
Notification to me:
oh - wonderful - means
Your http works. But https doesn’t answer.
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