Instalation Null Client in Debian

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Sendmail Null Client (Debian)

Installation

aptitude install sendmail

Setting-up

1. Replace ${ADMIN_EMAIL}, ${HOSTNAME}, ${DNS_DOMAIN}, ${IP_ADDR} for the adequate values.

2. Redirect messages from root, postmaster, admin, etc, to the administrator.

Edit /etc/mail/aliases

File: /etc/mail/aliases

<nowiki>
...
operator: root
admin: root
root: ${ADMIN_EMAIL}
...

</nowiki>

Update the aliases database:

/usr/sbin/newaliases

4. Verify that sendmail knows about the different names that the client can have.

Edit /etc/mail/local-host-names

File: /etc/mail/local-host-names

<nowiki>
...
 localhost
 localhost.localdomain
 ${HOSTNAME}
 ${HOSTNAME}.${DNS_DOMAIN}
...

</nowiki>

Verify that the host appears in /etc/hosts

File: /etc/hosts

...
${IP_ADDR}  ${HOSTNAME}.${DNS_DOMAIN}  ${HOSTNAME}
...

Edit /etc/mail/sendmail.mc

File: /etc/mail/sendmail.mc

...
dnl #
dnl # Masquerading options
FEATURE(`always_add_domain')dnl
MASQUERADE_AS(`${HOSTNAME}.${DNS_DOMAIN}')dnl
FEATURE(`allmasquerade')dnl
FEATURE(`masquerade_envelope')dnl
dnl #
dnl # Default Mailer setup
MAILER_DEFINITIONS
MAILER(`local')dnl
MAILER(`smtp')dnl
...

5. Activate the new configuration

yes | sendmailconfig

Security

By default Debian installs sendmail enabled only for localhost.
If tcp-wrappers are used, a line similar to the following should be added to /etc/hosts.allow

File: /etc/hosts.allow

...
sendmail: 127.0.0.1

If different filters are used, it's necessary to allow the access to the port localhost:25/tcp from localhost:1025/tcp

Cleaning-up (optional)

Remove ssmtp

aptitude remove ssmtp

If the DNS setup isn't defined in /etc/network/interfaces, remove resolvconf

aptitude remove resolvconf