Chapter 23, Problem 15RE

Explanation of Solution

Connecting to a POP server:

• POP server stands for Post Office Protocol.
• It is an application-layer Internet standard protocol which is used by email clients in order to retrieve email from a mail server.
• It defines the way user agents operate and how messages from and to mail transfer agents are formatted.
• POP is eventually going to be replaced by a new standard called Internet Mail Access Protocol.
• One can use the command “openssl s_client -connect pop.gmail.com:995”.
  • Here, 995 denotes the port number enable access it via SSL encryption.

The following shows the results of connection made to POP server.

~$ openssl s_client -connect pop.gmail.com:995

CONNECTED(00000003)

depth=1 C = US, O = Google Inc, CN = Google Internet Authority

verify error:num=20:unable to get local issuer certificate

verify return:0

---

Certificate chain

0 s:/C=US/ST=California/L=Mountain View/O=Google Inc/CN=pop.gmail.com

i:/C=US/O=Google Inc/CN=Google Internet Authority

1 s:/C=US/O=Google Inc/CN=Google Internet Authority

i:/C=US/O=Equifax/OU=Equifax Secure Certificate Authority

---

Server certificate

-----BEGIN CERTIFICATE-----

MIIDWjCCAsOgAwIBAgIKaNGwUQADAAAirzANBgkqhkiG9w0BAQUFADBGMQswCQYD

VQQGEwJVUzETMBEGA1UEChMKR29vZ2xlIEluYzEiMCAGA1UEAxMZR29vZ2xlIElu

dGVybmV0IEF1dGhvcml0eTAeFw0xMTAyMTYwNDQwMzdaFw0xMjAyMTYwNDUwMzda

MGcxCzAJBgNVBAYTAlVTMRMwEQYDVQQIEwpDYWxpZm9ybmlhMRYwFAYDVQQHEw1N

b3VudGFpbiBWaWV3MRMwEQYDVQQKEwpHb29nbGUgSW5jMRYwFAYDVQQDEw1wb3Au

Z22haWwuY29tMIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCc8H+gCR0/95Tb

Lkj7jdj0oXmfGzsSswdSjo6yWdcHpjv6cbaakHakclxBs47M8Gs3fJxuNqVMpt2Q

YorJuoBuVZjM59/rIeJwmOwSlzf1POxpEFUvm1ASAeBnBheBt0Fv+BCfI8DjZKgn

SvHCqQJfNgxpJBXOLbFVjBsPqF8w6wIDAQABo4IBLDCCASgwHQYDVR0OBBYEFHzY

GJFnJ+gmONoIX6cyTAEl9ePYMB8GA1UdIwQYMBaAFL/AMOv1QxE+Z7qekfv8atrj

axIkMFsGA1UdHwRUMFIwUKBOoEyGSmh0dHA6Ly93d3cuZ3N0YXRpYy5jb20vR29v

Z2xlSW50ZXJuZXRBdXRob3JpdHkvR29vZ2xlSW50ZXJuZXRBdXRob3JpdHkuY3Js

MGYGCCsGAQUFBwEBBFowWDBWBggrBgEFBQcwAoZKaHR0cDovL3d3dy5nc3RhdGlj

LmNvbS9Hb29nbGVJbnRlcm5ldEF1dGhvcml0eS9Hb29nbGVJbnRlcm5ldEF1dGhv

cml0eS5jcnQwIQYJKwYBBAGCNxQCBBQeEgBXAGUAYgBTAGUAcgB2AGUAcjANBgkq

hkiG9w0BAQUFAAOBgQB0GTFAoMNxCFJ3aVMzvrZgCD9hG2Ee3Sx5GMQ0yDjcFvzS

ZIci9Gr18HMVBusIuFLw8TvBD7PEXtZLhh6hbj+Xdg9CIqlIjdqJFRixJU06xqKH

akIhNBDxy5ky3VugqlGdysbMjo/aXCFdl42GproXdUPH24Erljur885LklMk/g==

-----END CERTIFICATE-----

subject=/C=US/ST=California/L=Mountain View/O=Google Inc/CN=pop...