I'm trying to connect to smtp.googlemail.com using openssl, from Ubuntu 16.04 I can login and send emails without any issue, but from Centos5 I'm getting this:
/usr/local/ssl/bin/openssl s_client -starttls smtp -connect smtp.googlemail.com:587 -crlf -ign_eof
CONNECTED(00000003)
depth=2 C = US, O = GeoTrust Inc., CN = GeoTrust Global CA
verify error:num=20:unable to get local issuer certificate
---
Certificate chain
0 s:/C=US/ST=California/L=Mountain View/O=Google Inc/CN=smtp.googlemail.com
i:/C=US/O=Google Inc/CN=Google Internet Authority G2
1 s:/C=US/O=Google Inc/CN=Google Internet Authority G2
i:/C=US/O=GeoTrust Inc./CN=GeoTrust Global CA
2 s:/C=US/O=GeoTrust Inc./CN=GeoTrust Global CA
i:/C=US/O=Equifax/OU=Equifax Secure Certificate Authority
---
Server certificate
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
subject=/C=US/ST=California/L=Mountain View/O=Google Inc/CN=smtp.googlemail.com
issuer=/C=US/O=Google Inc/CN=Google Internet Authority G2
---
No client certificate CA names sent
Peer signing digest: SHA256
Server Temp Key: ECDH, P-256, 256 bits
---
SSL handshake has read 4001 bytes and written 508 bytes
---
New, TLSv1/SSLv3, Cipher is ECDHE-RSA-AES128-GCM-SHA256
Server public key is 2048 bit
Secure Renegotiation IS supported
Compression: NONE
Expansion: NONE
No ALPN negotiated
SSL-Session:
Protocol : TLSv1.2
Cipher : ECDHE-RSA-AES128-GCM-SHA256
Session-ID: 917A4A945C1AD702E8F0588217413B3311AA226D7E78BDD87B8596965AA0D620
Session-ID-ctx:
Master-Key: 43A388B6FF51CFC304F63D3EEC61912670C38CF7ECB347F521C48CD094C333BBBE4532FBCB5D41203543B8F0D081C2BA
Key-Arg : None
PSK identity: None
PSK identity hint: None
SRP username: None
TLS session ticket lifetime hint: 100800 (seconds)
TLS session ticket:
0000 - bf cf bb fc 16 de 25 7a-cd bc 70 64 54 37 f0 60 ......%z..pdT7.`
0010 - 65 97 fe f6 65 24 c0 c6-5e 9f a8 e2 8f 5e 20 76 e...e$..^....^ v
0020 - 89 d7 f7 29 2c 43 fe f5-b9 95 c9 f3 ca 66 e6 cf ...),C.......f..
0030 - 53 20 86 84 1e 53 08 23-cf 14 56 23 d4 2f 45 1e S ...S.#..V#./E.
0040 - f1 68 0a d8 6a e1 06 e9-d5 d0 59 fc 86 df 0b f8 .h..j.....Y.....
0050 - 1b be d0 a3 40 83 3d 3c-d0 ce ba 07 a9 46 d7 6d ....@.=<.....F.m
0060 - 73 35 cd 72 04 3a 5b 90-a2 db 1a e2 7b 78 6e 90 s5.r.:[.....{xn.
0070 - 74 91 52 1e 10 68 15 58-5f b7 4d 0f ba 9e 2f 32 t.R..h.X_.M.../2
0080 - ac 78 92 37 47 d3 3c 3e-fd b0 ec 61 83 78 6e 48 .x.7G.<>...a.xnH
0090 - 61 27 ea 01 d7 74 3e 97-ab 72 05 00 78 3a 6d 9d a'...t>..r..x:m.
00a0 - b4 a0 57 e9 ..W.
Start Time: 1483556858
Timeout : 300 (sec)
Verify return code: 20 (unable to get local issuer certificate)
It looks like OpenSSL cannot find the root certificate needed, am I right?. Ok so, how can I fix this?.
