POP3 SSL && Fetchmail

 Posted on October 2, 2005  (Last modified on January 22, 2011)  |  3 minutes  |  592 words  |  

Small HOWTO on configuring POP3 SSL with Fetchmail.
Here I assume that the server’s SSL certificate is a Self Signed Certificate

  1. openssl s_client -connect mail.logicalwebhost.com:995 -showcerts
    Execute this command to fetch the details of the server and also the certificate.
    The output will be something like below:

rrs@laptop:~ $ openssl s_client -connect mail.someserver.com:995 -showcerts
CONNECTED
depth=0 /C=US/ST=CA/L=San Jose/O=Some Internet Hosting Services/OU =Automatically-generated POP3 SSL key/CN=mail.somehost.com/emailAddress=postmaster@researchut.com
verify error:num=18:self signed certificate
verify return:1
depth=0 /C=US/ST=CA/L=San Jose/O=Some Internet Hosting Services/OU =Automatically-generated POP3 SSL key/CN=mail.somehost.com/emailAddress=postmaster@researchut.com
verify return:1

Certificate chain 0 s:/C=US/ST=CA/L=San Jose/O=Some Internet Hosting Services/OU=Automatically-generated POP3 SSL key/CN=mail.somehost.com/emailAddress=postmaster@researchut.com i:/C=US/ST=CA/L=San Jose/O=Some Internet Hosting Services/OU=Automatically- generated POP3 SSL key/CN=mail.somehost.com/emailAddress=postmaster@researchut.com

---- BEGIN CERTIFICATE ----
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---- END CERTIFICATE ----

Server certificate
subject=/C=US/ST=CA/L=San Jose/O=Some Internet Hosting Services/OU =Automatically-generated POP3 SSL key/CN=mail.somehost.com/emailAddress=postmaster@researchut.com
issuer=/C=US/ST=CA/L=San Jose/O=Some Internet Hosting Services/OU =Automatically-generated POP3 SSL key/CN=mail.somehost.com/emailAddress=postmaster@researchut.com

No client certificate CA names sent

SSL handshake has read 999 bytes and written 340 bytes

New, TLSv1/SSLv3, Cipher is AES256-SHA
Server public key is 1024 bit
SSL-Session: Protocol : TLSv1 Cipher : AES256-SHA Session-ID: F2B956727C31F224E04E1A869B933E761C3E3A5D6D9130983C1B521B5C02EC0A Session-ID- ctx: Master-Key: 4511A691DA22F4439063BBE5E3DB1D6F90547F2F340952F3992A3FFB1B8C9855614333E6373DFDE40ADF6F7CBBE99E93 Key-Arg : None Start Time: 1128203230 Timeout : 300 (sec) Verify return code: 18 (self signed certificate)

+OK Hello there.

  1. Copy the certificate beginning from

    “—- BEGIN CERTIFICATE —-” to “—- END CERTIFICATE —-”

and save it with some name (foo.pem) into your ~/.certs folder

  1. Run, c_rehash ~/.certs. You’ll get some output like the following
    rrs@laptop:~ $ c_rehash .certs/
    Doing .certs/
    googlepop.pem => 34ceaf75.0
    thwate.pem => ddc328ff.0
    mail.somehost.com.pem => e76e0724.0

Notice the “somehost” line. That’s what your certificates output is.

  1. Now configure your .fetchmailrc as follows
    poll mail.somehost.com with proto POP3 user ‘username’ there with password ‘passWord’ is ‘rrs’ here options flush no rewrite ssl sslcertck sslcertpath ‘/home/rrs/.certs/’ smtphost localhost

  2. Run fetchmail with the -v option to run in verbose mode to see the output. You should see something like the following:

Oct 2 03:13:34 laptop fetchmail12287: 6.2.5 querying mail.somehost.com (protocol POP3) at Sun 02 Oct 2005 03:13:34 AM IST: poll started
Oct 2 03:13:38 laptop fetchmail12287: Issuer Organization: Some Internet Hosting Services
Oct 2 03:13:38 laptop fetchmail12287: Issuer CommonName: mail.somehost.com
Oct 2 03:13:38 laptop fetchmail12287: Server CommonName: mail.somehost.com
Oct 2 03:13:38 laptop fetchmail12287: mail.somehost.com key fingerprint: 15:16:28:C3:60:82:E1:AE:D3:77:77:80:DC:BC
:F0:57
Oct 2 03:13:40 laptop fetchmail12287: POP3< +OK Hello there.
Oct 2 03:13:40 laptop fetchmail12287: POP3> CAPA
Oct 2 03:13:41 laptop fetchmail12287: POP3< +OK Here’s what I can do:
Oct 2 03:13:41 laptop fetchmail12287: POP3< STLS
Oct 2 03:13:41 laptop fetchmail12287: POP3< TOP
Oct 2 03:13:41 laptop fetchmail12287: POP3< USER
Oct 2 03:13:41 laptop fetchmail12287: POP3< LOGIN-DELAY 10
Oct 2 03:13:41 laptop fetchmail12287: POP3< PIPELINING
Oct 2 03:13:41 laptop fetchmail12287: POP3< UIDL
Oct 2 03:13:41 laptop fetchmail12287: POP3< IMPLEMENTATION Courier Mail Server
Oct 2 03:13:41 laptop fetchmail12287: POP3< .
Oct 2 03:13:41 laptop fetchmail12287: POP3> USER user@domain.com
Oct 2 03:13:42 laptop fetchmail12287: POP3< +OK Password required.
Oct 2 03:13:42 laptop fetchmail12287: POP3> PASS *
Oct 2 03:13:44 laptop fetchmail12287: POP3< +OK logged in.
Oct 2 03:13:47 laptop fetchmail12287: POP3> STAT
Oct 2 03:13:48 laptop fetchmail12287: POP3< +OK 0 0
Oct 2 03:13:48 laptop fetchmail12287: No mail for user@domain.com at mail.somehost.com
Oct 2 03:13:48 laptop fetchmail12287: POP3> QUIT
Oct 2 03:13:49 laptop fetchmail12287: POP3< +OK Bye-bye.
Oct 2 03:13:49 laptop fetchmail12287: 6.2.5 querying mail.somehost.com (protocol POP3) at Sun 02 Oct 2005 03:13:49 AM IST: poll completed

That’s it. Your fetchmail is configured to fetch mails using POP3 SSL. Now you’re much safer with your passwords.
Please drop a comment if you find this small HOWTO useful.