September 14, 2020
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Certificates for VPN, SSL Offloading (if using Load balancing), or a signed device cert expire, we all know this. Up until last week I had never updated a signed certificate, I had just created a new CSR, and rekeyed the cert. Updating the certificate the Fortigate is using is very easy, but I had problems with the syntax so I am documenting it here.
The Fortinet KB article to do it is located here:
I had an issue following the doc so I though I would clear the water and see if I could help someone down the road. Lets say I have sslvpn.travelingpacket.com that will expire in 2 days – I log into my CA (godaddy in my case) and renew the cert. They send the new cert to me, but what do I do with it…
Open the cert with a text editor – maybe notepad – and copy the cert. you should see —BEGIN CERTIFICATE. Copy everything. Then log into the fortigate VIA cli – Putty or some kind of SSL client is way better for doing this then the web client. Then lets modify the certificate
config vpn certificate local
edit sslvpn (or your cert name)
set certificate “—–BEGIN CERTIFICATE—– mPjDQDYkYHKcTrGa6aH7e1w1uM7kdaBAjyAgM7xcmuTrsCeLYfd+BwIDAQABo4IDTDCCA0gwPQYJKwYBBAGCNxUHBDAwLgYmKwYBBAGCNxUIorRWhO7dYIKtkziB9KY0
and Press enter – The issues I had was with the quotes. I tried to first do double quotes, and past the cert in the middle – that does not work. Just simply type in the command set certificate and then a double quote “ and past the cert whole. After its pastes do the ending quote “ and press enter. Thats it for modifying the cert – but to enact it we have to remove it from whatever we are using it for, and then add it back. That refreshes the cert. So if your using it for SSL-VPN , go to VPN – SSL-VPN settings – and set the server cert to a different one, press apply, and change it back.