Prove it:
$ cat > issuer.pem <<EOF
2 subject: /C=US/O=GeoTrust Inc./CN=GeoTrust Global CA
issuer: /C=US/O=Equifax/OU=Equifax Secure Certificate Authority
cert digest=73:59:75:5C:6D:F9:A0:AB:C3:06:0B:CE:36:95:64:C8:EC:45:42:A3
pkey digest=C0:7A:98:68:8D:89:FB:AB:05:64:0C:11:7D:AA:7D:65:B8:CA:CC:4E
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
EOF
I guess I'm confused about something. Below are the relevant entries in
my /etc/ssl/certs/ca-certificates.crt file for google. This was obtained
by running the "openssl s_client -CAfile ca.pem -starttls smtp
-showcerts -connect alt4.gmail-smtp-in.l.google.com:25":
-----BEGIN CERTIFICATE-----
MIIGhDCCBWygAwIBAgIIa7+rjwrecGgwDQYJKoZIhvcNAQEFBQAwSTELMAkGA1UE
BhMCVVMxEzARBgNVBAoTCkdvb2dsZSBJbmMxJTAjBgNVBAMTHEdvb2dsZSBJbnRl
cm5ldCBBdXRob3JpdHkgRzIwHhcNMTQwNzE1MDg1NjE2WhcNMTUwNDA0MTUxNTU1
WjBnMQswCQYDVQQGEwJVUzETMBEGA1UECAwKQ2FsaWZvcm5pYTEWMBQGA1UEBwwN
TW91bnRhaW4gVmlldzETMBEGA1UECgwKR29vZ2xlIEluYzEWMBQGA1UEAwwNbXgu
Z29vZ2xlLmNvbTCCASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQoCggEBALXdZYGb
7GeyejZTesdEdsOt++RnNBWbXrpJR4pXU6F0iHzSBoP6FJLx755vKFlc7H/LicAL
dATo8MT6mPlJLUByivEQBzt+ueZOX1iNcYw3NEZXRjtEllxyYmQfHNFatjNAhCwV
o9euyYkut8CVwS/QJccCHs6fNoD7FcXJu8XfiRS2asKwFtxosXxH54VaOwNaeGbC
UOcT8jxYD5Nnp2luQZofVCIeeHOG9kRP7sUDdBvX7uTneetZLkn2CQQoisd9I4QE
6Gq3GRPeE9MkcY7e71+CYkTdUVLfzIYmkmg/MaN7rce4gTCzvQJ8D7ZF14GKk3Ih
YHSTda5NRUARp/0CAwEAAaOCA1AwggNMMB0GA1UdJQQWMBQGCCsGAQUFBwMBBggr
BgEFBQcDAjCCAiYGA1UdEQSCAh0wggIZghJhc3BteC5sLmdvb2dsZS5jb22CF2Fs
dDEuYXNwbXgubC5nb29nbGUuY29tghdhbHQyLmFzcG14LmwuZ29vZ2xlLmNvbYIX
YWx0My5hc3BteC5sLmdvb2dsZS5jb22CF2FsdDQuYXNwbXgubC5nb29nbGUuY29t
ghpnbWFpbC1zbXRwLWluLmwuZ29vZ2xlLmNvbYIfYWx0MS5nbWFpbC1zbXRwLWlu
LmwuZ29vZ2xlLmNvbYIfYWx0Mi5nbWFpbC1zbXRwLWluLmwuZ29vZ2xlLmNvbYIf
YWx0My5nbWFpbC1zbXRwLWluLmwuZ29vZ2xlLmNvbYIfYWx0NC5nbWFpbC1zbXRw
LWluLmwuZ29vZ2xlLmNvbYIYZ21yLXNtdHAtaW4ubC5nb29nbGUuY29tgh1hbHQx
Lmdtci1zbXRwLWluLmwuZ29vZ2xlLmNvbYIdYWx0Mi5nbXItc210cC1pbi5sLmdv
b2dsZS5jb22CHWFsdDMuZ21yLXNtdHAtaW4ubC5nb29nbGUuY29tgh1hbHQ0Lmdt
ci1zbXRwLWluLmwuZ29vZ2xlLmNvbYINbXguZ29vZ2xlLmNvbYIVYXNwbXgyLmdv
b2dsZW1haWwuY29tghVhc3BteDMuZ29vZ2xlbWFpbC5jb22CFWFzcG14NC5nb29n
bGVtYWlsLmNvbYIVYXNwbXg1Lmdvb2dsZW1haWwuY29tMGgGCCsGAQUFBwEBBFww
WjArBggrBgEFBQcwAoYfaHR0cDovL3BraS5nb29nbGUuY29tL0dJQUcyLmNydDAr
BggrBgEFBQcwAYYfaHR0cDovL2NsaWVudHMxLmdvb2dsZS5jb20vb2NzcDAdBgNV
HQ4EFgQUBZHrxONQ35UlBbfg/kH906dTK4YwDAYDVR0TAQH/BAIwADAfBgNVHSME
GDAWgBRK3QYWG7z2aLV29YG2u2IaulqBLzAXBgNVHSAEEDAOMAwGCisGAQQB1nkC
BQEwMAYDVR0fBCkwJzAloCOgIYYfaHR0cDovL3BraS5nb29nbGUuY29tL0dJQUcy
LmNybDANBgkqhkiG9w0BAQUFAAOCAQEAcdpfy9yMh4NR4jtm7MPkk11iL81mDbTy
3L/sO2p1NrEUTiUtVKhV0hwOO7+tsOTfd1iR07QUFCiRW2GTlGpy4gvgXdAleT7e
1kKRIrD4p7O99xhmoKbaNVIGHMHoP393dmoFOV+OzdMjN4NTZwyvKieo5RuE/zOW
yjFt89bvnApJcpnY6sHoWeKvioBA4YiCU/U1Cb/8DMZ9yX9RkSqUJ0gosInMkTKg
H0wvLQNhSkbUYaRPme9FjFrvgDx/IFmzS1Fx2qSwRJUuAwbPd9cOefi+eXAfg9Mx
3aZYDlObs8lWrwjARkl9HpGdI4WUTRMwSCSuf51npgwVaa+PIiX9fg==
-----END CERTIFICATE-----
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
