I have a server on a LAN that need to send emails. Of course, this server has access to the internet through NAT, but for emails it is a bit more difficult : nowadays, email servers are checking many things when receiving emails : reverse, ‘from’\u00a0field, etc. and you may not have access to this kind of tuning for the internet IP address used with your NAT. So I needed to configure a relayhost, with direct access to the internet, that would accept my incoming email and relay it through normal channels. But I don’t want this server to be an open relay, so I have to setup authentication between them.<\/p>\n
<\/p>\n
Configuration on Postfix is quite easy :<\/p>\n
relayhost = my.relayhost.com:587\r\nsmtp_sasl_auth_enable = yes\r\nsmtp_sasl_password_maps = hash:\/etc\/postfix\/sasl_passwd\r\nsmtp_sasl_security_options = noanonymous\r\nsmtp_use_tls = yes\r\nsmtp_tls_CAfile = \/etc\/pki\/tls\/certs\/ca-bundle.crt<\/pre>\nNow, let’s create file\u00a0\/etc\/postfix\/sasl_passwd :<\/p>\n
my.relayhost.com:587 myuser@mydomain.com:mYSupErPassw0rd<\/pre>\nCreate the hash for this file :<\/p>\n
$ postmap\u00a0\/etc\/postfix\/sasl_passwd<\/pre>\nThen restart Postfix and let’s try if everything is working :<\/p>\n
postfix\/qmgr[44536]: 62A2D16012B: from=<root@xxxxx>, size=438, nrcpt=1 (queue active)\r\npostfix\/smtp[44689]: warning: SASL authentication failure: No worthy mechs found\r\npostfix\/smtp[44689]: 62A2D16012B: to=<test@test.com>, relay=my.relayhost.com[X.X.X.X]:587, delay=10, delays=10\/0.04\/0.04\/0, dsn=4.7.0, status=deferred (SASL authentication failed; cannot authenticate to server my.relayhost.com[X.X.X.X]: no mechanism available)<\/pre>\nDamn, there is an authentication error it seems. I double check my password … No, it is not the issue. Let’s focus on the error message :<\/p>\n
no mechanism available<\/p><\/blockquote>\n
So, it seems Postfix did not find any auth mechanism suitable. I know my relayhost is using PLAIN SASL auth … Maybe I’m missing some libs :<\/p>\n
$ rpm -qa |fgrep sasl\r\ncyrus-sasl-lib-2.1.23-15.el6_6.2.x86_64\r\ncyrus-sasl-2.1.23-15.el6_6.2.x86_64<\/pre>\nHere, I need lib cyrus-sasl-plain ! Let’s install and retry :<\/p>\n
$ yum install -y\u00a0cyrus-sasl-plain\r\n$ \/etc\/init.d\/postfix restart\r\n$ postqueue -f<\/pre>\npostfix\/smtp[556]: F297016012E: to=<test@test.com>, relay=my.relayhost.com[X.X.X.X]:587, delay=0.35, delays=0.01\/0.04\/0.28\/0.01, dsn=2.0.0, status=sent (250 2.0.0 Ok: queued as EDF5C449D)<\/pre>\nAnd voil\u00e0 ! It works !<\/p>\n","protected":false},"excerpt":{"rendered":"
I have a server on a LAN that need to send emails. Of course, this server has access to the internet through NAT, but for emails it is a bit more difficult : nowadays, email servers are checking many things when receiving emails : reverse, ‘from’\u00a0field, etc. and you may not have access to this … Continuer la lecture de using a secured relay in Postfix<\/span>