Postfix "warning: cannot get RSA private key from file"
- by phew
I just followed this tutorial to set up a postfix mailserver with dovecot and mysql as backend for virtual users.
Now I got the most parts working, I can connect to pop3 pop3s imap and imaps.
Using
echo TEST-MAIL | mail [email protected]
works fine, when I log into my hotmail account it shows the email.
It also works in reverse hence my MX entry for mydomain.com finally has been propagated, so I am being able to receive emails sent from [email protected] to [email protected] and view them in Thunderbird using STARTTLS via IMAP.
Doing a bit more research after I got the error message "5.7.1 : Relay access denied" when trying to send mails to [email protected] using Thunderbird being logged into [email protected], I figured out that my server was acting as an "Open Mail Relay", which - ofcourse - is a bad thing.
Digging more into the optional parts of the tutorial like shown workaround.org/comment/2536 and workaround.org/ispmail/squeeze/postfix-smtp-auth I decided to complete these steps aswell to be able to send mails via [email protected] through Mozilla Thunderbird, not getting the error message "5.7.1 : Relay access denied" anymore (as common mailservers reject open relayed emails).
But now I ran into an error trying to get postfix working with SMTPS, in /var/log/mail.log it reads
Sep 28 17:29:34 domain postfix/smtpd[20251]: warning: cannot get RSA private key from file /etc/ssl/certs/postfix.pem: disabling TLS support
Sep 28 17:29:34 domain postfix/smtpd[20251]: warning: TLS library problem: 20251:error:0906D06C:PEM routines:PEM_read_bio:no start line:pem_lib.c:650:Expecting: ANY PRIVATE KEY:
Sep 28 17:29:34 domain postfix/smtpd[20251]: warning: TLS library problem: 20251:error:140B0009:SSL routines:SSL_CTX_use_PrivateKey_file:PEM lib:ssl_rsa.c:669:
That error is logged right after I try to send a mail from my newly installed mailserver using SMTP SSL/TLS via port 465 in Thunderbird. Thunderbird then tells me a timeout occured.
Google has a few results concerning that problem, yet I couldn't get it working with any of those. I would link some of them here but as a new user I am only allowed to use two hyperlinks.
My /etc/postfix/master.cf looks like
smtp inet n - - - - smtpd
smtps inet n - - - - smtpd
-o smtpd_tls_wrappermode=yes
-o smtpd_sasl_auth_enable=yes
and nmap tells me
PORT STATE SERVICE
[...]
465/tcp open smtps
[...]
my /etc/postfix/main.cf looks like
smtpd_banner = $myhostname ESMTP $mail_name (Debian/GNU)
biff = no
append_dot_mydomain = no
readme_directory = no
#smtpd_tls_cert_file = /etc/ssl/certs/postfix.pem #default postfix generated
#smtpd_tls_key_file = /etc/ssl/private/ssl-cert-snakeoil.key #default postfix generated
smtpd_tls_cert_file = /etc/ssl/certs/postfix.pem
smptd_tls_key_file = /etc/ssl/private/postfix.pem
smtpd_use_tls = yes
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
smtpd_sasl_type = dovecot
smtpd_sasl_path = private/auth
smptd_sasl_auth_enable = yes
smtpd_recipient_restrictions = permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination
myhostname = mydomain.com
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
myorigin = /etc/mailname
mydestination = localhost.com, localhost
relayhost =
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all
virtual_mailbox_domains = mysql:/etc/postfix/mysql-virtual-mailbox-domains.cf
virtual_mailbox_maps = mysql:/etc/postfix/mysql-virtual-mailbox-maps.cf
virtual_alias_maps = mysql:/etc/postfix/mysql-virtual-alias-maps.cf
virtual_transport = dovecot
dovecot_destination_recipient_limit = 1
mailbox_command = /usr/lib/dovecot/deliver
The *.pem files were created like described in the tutorial above, using
Postfix
To create a certificate to be used by Postfix use:
openssl req -new -x509 -days 3650 -nodes -out /etc/ssl/certs/postfix.pem -keyout /etc/ssl/private/postfix.pem
Do not forget to set the permissions on the private key so that no unauthorized people can read it:
chmod o= /etc/ssl/private/postfix.pem
You will have to tell Postfix where to find your certificate and private key because by default it will look for a dummy certificate file called "ssl-cert-snakeoil":
postconf -e smtpd_tls_cert_file=/etc/ssl/certs/postfix.pem
postconf -e smtpd_tls_key_file=/etc/ssl/private/postfix.pem
I think I don't have to include /etc/dovecot/dovecot.conf here, as login via imaps and pop3s works fine according to the logs. Only problem is making postfix properly use the self-generated, self-signed certificates.
Any help appreciated!
EDIT:
I just tried this different tutorial on generating a self-signed certificate for postfix, still getting the same error. I really don't know what else to test.
I also did check for the SSL libraries, but all seems to be fine:
root@domain:~# ldd /usr/sbin/postfix
linux-vdso.so.1 => (0x00007fff91b25000)
libpostfix-global.so.1 => /usr/lib/libpostfix-global.so.1 (0x00007f6f8313d000)
libpostfix-util.so.1 => /usr/lib/libpostfix-util.so.1 (0x00007f6f82f07000)
libssl.so.0.9.8 => /usr/lib/libssl.so.0.9.8 (0x00007f6f82cb1000)
libcrypto.so.0.9.8 => /usr/lib/libcrypto.so.0.9.8 (0x00007f6f82910000)
libsasl2.so.2 => /usr/lib/libsasl2.so.2 (0x00007f6f826f7000)
libdb-4.8.so => /usr/lib/libdb-4.8.so (0x00007f6f8237c000)
libnsl.so.1 => /lib/libnsl.so.1 (0x00007f6f82164000)
libresolv.so.2 => /lib/libresolv.so.2 (0x00007f6f81f4e000)
libc.so.6 => /lib/libc.so.6 (0x00007f6f81beb000)
libdl.so.2 => /lib/libdl.so.2 (0x00007f6f819e7000)
libz.so.1 => /usr/lib/libz.so.1 (0x00007f6f817d0000)
libpthread.so.0 => /lib/libpthread.so.0 (0x00007f6f815b3000)
/lib64/ld-linux-x86-64.so.2 (0x00007f6f83581000)
After following Ansgar Wiechers instructions its finally working.
postconf -n contained the lines as it should. The certificate/key check via openssl did show that both files are valid.
So it indeed has been a permissions problem! Didn't know that chown'ing the /etc/ssl/*/postfix.pem files to postfix:postfix is not enough for postfix to read the files.
