[stunnel-users] Help with connectivity issue

Rob Allen robert.allen at eyefinity.com
Fri Sep 15 21:05:35 CEST 2017

I’ve installed stunnel on an Amazon EC2 instance:

stunnel 4.56 on x86_64-redhat-linux-gnu platform
Compiled/running with OpenSSL 1.0.1e-fips 11 Feb 2013

Global options:
debug                  = daemon.notice
pid                    = /var/run/stunnel.pid
RNDbytes               = 64
RNDfile                = /dev/urandom
RNDoverwrite           = yes

Service-level options:
ciphers                = FIPS (with "fips = yes")
ciphers                = ALL:!SSLv2:!aNULL:!EXP:!LOW:-MEDIUM:RC4:+HIGH (with "fips = no")
curve                  = prime256v1
sessionCacheSize       = 1000
sessionCacheTimeout    = 300 seconds
sslVersion             = TLSv1 (with "fips = yes")
sslVersion             = TLSv1 for client, all for server (with "fips = no")
stack                  = 65536 bytes
TIMEOUTbusy            = 300 seconds
TIMEOUTclose           = 60 seconds
TIMEOUTconnect         = 10 seconds
TIMEOUTidle            = 43200 seconds
verify                 = none

I’ve created the stunnel.conf file:

accept = 2525
client = yes
connect = email-smtp.us-west-2.amazonaws.com:465
delay = yes

I’ve tested the connection to SES (successfully) via openssl:

[ec2-user at ip-172-31-4-68 ~]$ openssl s_client -quiet -crlf -connect email-smtp.us-west-2.amazonaws.com:465
depth=2 C = US, O = "VeriSign, Inc.", OU = VeriSign Trust Network, OU = "(c) 2006 VeriSign, Inc. - For authorized use only", CN = VeriSign Class 3 Public Primary Certification Authority - G5
verify return:1
depth=1 C = US, O = Symantec Corporation, OU = Symantec Trust Network, CN = Symantec Class 3 Secure Server CA - G4
verify return:1
depth=0 C = US, ST = Washington, L = Seattle, O = "Amazon.com, Inc.", CN = email-smtp.us-west-2.amazonaws.com
verify return:1
220 email-smtp.amazonaws.com ESMTP SimpleEmailService-2370111491 wa7VtNk9b7c4TX0jNpdG

But when I try to access through stunnel via localhost with telnet, I get this:

[ec2-user at ip-172-31-4-68 ~]$ telnet localhost 2525
Trying ::1...
telnet: connect to address ::1: Connection refused
Connected to localhost.
Escape character is '^]'.
Connection closed by foreign host.

I’ve tried everything I can think of; I’ve read all the blogs and pages related to connecting from ec2 to SES via stunnel and I just can’t get it to work.  Does anyone have any suggestions for other things I could try?

Thanks in advance,
Rob Allen, CPO
Software Engineer | Eyefinity
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