I recently moved my TLS termination back to my reverse proxy from the backend server, and I have run into this very specific problem.
When connecting to my nextcloud site firefox says SEC_ERROR_UNKNOWN_ISSUER.
More info on the error (cert info at bottom):
https://nextcloud.domain.com/
Peer’s Certificate issuer is not recognized.
HTTP Strict Transport Security: false
HTTP Public Key Pinning: false
The weird part is that this problem does not occur on any other browser, just firefox (Firefox 95, Ubuntu 20.04, Windows 10, and Android 12; no extensions). It only occurs after browsing initially to the site, then closing firefox, then reopening it and browsing to any url on nextcloud and the error occurs. Unfortunately its not exact that the error occurs on the second browsing, but it will happen whether its the second, third, or fourth time browsing after a firefox restart. I can resolve the error by restarting nginx on my reverse proxy.
To be clear, it appears the firefox restart triggers it; closing the tab and reopening does not produce the error. I have also tried clearing Firefox of the site data and restarting, error still happens.
The stranger part is that I have a couple other sites on the same reverse proxy using lets encrypt certs (different sub domain) and I cannot replicate the error there. It seems to be confined to firefox+nextcloud+nginx. Although restarting the backend nginx/server does not affect it. So I suppose there should be a specific configuration that I am missing on my reverse proxy.
I am at a loss here, the only thing that has changed is where the TLS is being terminated and a new Lets Encrypt cert. Hopefully I am missing something obvious and this isn't a bigger problem.
Full nginx configuration (minus other subdomains and mime types):
nginx: the configuration file /etc/nginx/nginx.conf syntax is ok
nginx: configuration file /etc/nginx/nginx.conf test is successful
# configuration file /etc/nginx/nginx.conf:
user www-data;
worker_processes auto;
pid /run/nginx.pid;
include /etc/nginx/modules-enabled/*.conf;
events {
worker_connections 768;
# multi_accept on;
}
http {
##
# Basic Settings
##
sendfile on;
tcp_nopush on;
tcp_nodelay on;
keepalive_timeout 65;
types_hash_max_size 2048;
server_tokens off;
# server_names_hash_bucket_size 64;
# server_name_in_redirect off;
include /etc/nginx/mime.types;
default_type application/octet-stream;
##
# SSL Settings
##
ssl_protocols TLSv1.2 TLSv1.3;
ssl_prefer_server_ciphers on;
##
# Logging Settings
##
##
# Gzip Settings
##
gzip on;
# gzip_vary on;
# gzip_proxied any;
# gzip_comp_level 6;
# gzip_buffers 16 8k;
# gzip_http_version 1.1;
# gzip_types text/plain text/css application/json application/javascript text/xml application/xml application/xml+rss text/javascript;
##
# Virtual Host Configs
##
include /etc/nginx/sites-enabled/*;
##
# Hardening
##
add_header Allow "GET, POST, HEAD" always;
add_header X-XSS-Protection "1; mode=block";
}
# configuration file /etc/nginx/snippets/ssl-params.conf:
ssl_protocols TLSv1.2 TLSv1.3;
ssl_prefer_server_ciphers on;
ssl_ciphers "EECDH+ECDSA+AESGCM EECDH+aRSA+AESGCM EECDH+ECDSA+SHA384 EECDH+ECDSA+SHA256 EECDH+aRSA+SHA384 EECDH+aRSA+SHA256 EECDH+aRSA+RC4 EECDH EDH+aRSA HIGH !RC4 !aNULL !eNULL !LOW !3DES !MD5 !EXP !PSK !SRP !DSS";
ssl_ecdh_curve secp384r1;
ssl_session_cache shared:SSL:10m;
ssl_session_tickets off;
ssl_stapling on;
ssl_stapling_verify on;
resolver 1.1.1.1 valid=300s;
resolver_timeout 5s;
# Disable preloading HSTS for now. You can use the commented out header line that includes
# the "preload" directive if you understand the implications.
add_header Strict-Transport-Security "max-age=15552000; includeSubdomains; preload";
add_header X-Frame-Options "DENY" always;
add_header X-Content-Type-Options "nosniff" always;
add_header Referrer-Policy "no-referrer" always;
add_header X-Download-Options "noopen" always;
add_header X-Permitted-Cross-Domain-Policies "none" always;
add_header X-Robots-Tag "none" always;
add_header X-XSS-Protection "1; mode=block" always;
ssl_dhparam /etc/ssl/certs/dhparam.pem;
# configuration file /etc/nginx/sites-enabled/nextcloud.domain.com:
server {
listen 443 ssl http2;
ssl_certificate /etc/letsencrypt/live/nextcloud.domain.com/fullchain.pem;
ssl_certificate_key /etc/letsencrypt/live/nextcloud.domain.com/privkey.pem;
include snippets/ssl-params.conf;
server_name nextcloud.domain.com;
location / {
proxy_pass https://BACKENDIP;
proxy_set_header X-Real-IP $remote_addr;
}
}
# configuration file /etc/nginx/sites-enabled/reverseproxy.conf:
server {
listen 80;
server_name _;
return 301 https://$host$request_uri;
}
Some info from the server cert via firefox:
Subject Name
Common Name nextcloud.domain.com
Issuer Name
Country US
Organization Let's Encrypt
Common Name R3
Validity
Not Before Fri, 10 Dec 2021 19:29:21 GMT
Not After Thu, 10 Mar 2022 19:29:20 GMT
Intermediate cert:
Subject Name
Country US
Organization Let's Encrypt
Common Name R3
Issuer Name
Country US
Organization Internet Security Research Group
Common Name ISRG Root X1
Validity
Not Before Fri, 04 Sep 2020 00:00:00 GMT
Not After Mon, 15 Sep 2025 16:00:00 GMT
Root Cert:
Subject Name
Country US
Organization Internet Security Research Group
Common Name ISRG Root X1
Issuer Name
Organization Digital Signature Trust Co.
Common Name DST Root CA X3
Validity
Not Before Wed, 20 Jan 2021 19:14:03 GMT
Not After Mon, 30 Sep 2024 18:14:03 GMT
No errors on the proxy or server associated with anything. The HTTP request shows up as code 200.
Here is a comparison between two certs on two of my servers that were both issued through Lets Encrypt Certbot minutes apart:
This is the cert firefox has a problem with:
This is the cert firefox accepts:
A slightly concerning problem is that when browsing to the site firefox doesn't trust, in chrome, I get a root certificate that is NOT issued by the same organization.