linkedin.com
HTTPS & TLS
100/100A+- HTTPS certificateDigiCert Inc10/10
HTTPS with a valid certificate from DigiCert Inc.
- Certificate expiry1324/4
The certificate is valid for another 132 days.
- TLS versionTLS 1.34/4
Negotiates TLS 1.3, the current protocol: faster handshakes, forward secrecy always.
- Old protocols3/3
Refuses the retired TLS 1.0 and 1.1.
- Key strengthRSA 20482/2
A strong key: RSA 2048.
- HTTP → HTTPS3013/3
http:// redirects straight to https://.
- HSTS1 year4/4
HSTS tells browsers to use HTTPS only, for 1 year.
- HTTP/2 and HTTP/3HTTP/32/2
HTTP/2 and HTTP/3.
DNS
79/100B- DNSSEC0/3
Not signed with DNSSEC: a forged DNS answer for the domain cannot be told from the real one.
- Name servers84/4
8 name servers for the domain.
- Name servers answer8/85/5
Every name server answers for the domain, with the same version of the zone.
- CAA records2/2
CAA records name the authorities allowed to issue its certificates.
- MTA-STS0/2
No MTA-STS: mail to the domain can be read in transit by stripping its encryption.
- SPF~all4/5
SPF lists the servers allowed to send its mail and marks the rest as suspicious (~all).
- DMARCreject7/7
DMARC tells receivers to reject mail that fakes the domain (p=reject).
- TLS reporting0.5/0.5
TLS reporting: senders report failed encrypted deliveries.
- DKIMgoogle2/2
A DKIM key is published (selector google), so its mail can be signed.
Web & network
94/100A- Referrer-Policy0/0.5
No Referrer-Policy of its own (browsers' default applies).
- Permissions-Policy0/0.5
No Permissions-Policy: embedded content may ask for camera, microphone or location.
- Content Security Policy3/3
A Content Security Policy limits which scripts the pages run.
- X-Content-Type-Options2/2
X-Content-Type-Options: nosniff stops browsers guessing file types.
- Framing2/2
Other sites cannot frame its pages (clickjacking protection).
- IPv64/4
www.linkedin.com is reachable over IPv6 as well as IPv4.
- RPKIvalid4/4
The route to the website is RPKI-valid: networks can reject hijacked announcements of it.
Dependencies
100/100A+- DNS providersNS1, Azure DNS5/5
DNS is served by 2 providers: one can fail without taking the domain offline.
- One company for everything5/5
The website, DNS and email do not all hang on one company.
Who runs it
- Website
- Cloudflare
- DNS
- NS1Azure DNS
- Self-hosted
Routes
- 104.18.41.0/24AS13335RPKI valid
- 2a06:98c1:310b::/48AS13335RPKI valid
Name servers
- dns1.p09.nsone.netNS1AS62597
- dns2.p09.nsone.netNS1AS62597
- dns3.p09.nsone.netNS1AS62597
- dns4.p09.nsone.netNS1AS62597
- ns1-42.azure-dns.comAzure DNSAS8075
- ns2-42.azure-dns.netAzure DNSAS8075
- ns3-42.azure-dns.orgAzure DNSAS8075
- ns4-42.azure-dns.infoAzure DNSAS8075
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What is graded
A valid certificate (an invalid one means F), its expiry against its lifetime, TLS 1.3, no TLS 1.0/1.1 (else at most B), http:// sent straight to https://, HSTS, HTTP/2.
At least two name servers that all answer and agree, DNSSEC, CAA records, and a registration that is not about to expire.
SPF, a DMARC policy that rejects forgeries (none means at most B), MTA-STS and TLS reporting for domains that take mail, DKIM at common selectors.
Content Security Policy, nosniff, framing protection, Referrer- and Permissions-Policy, IPv6, and an RPKI-valid route (invalid means at most C).
DNS from more than one provider, and the website, DNS and email not all with one company.
A+ 95–100 · A 85–94 · B 75–84 · C 65–74 · D 50–64 · F below 50