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@@ -11,18 +11,18 @@ as forwarder.
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Sender Rewriting Scheme Crash Course
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------------------------------------
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-Imagine your server receives a mail from alice@example.com
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+Imagine your server receives a mail from `alice@example.com`
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that is to be forwarded. If example.com uses the Sender Policy Framework
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to indicate that all legit mails originate from their server, your
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forwarded mail might be bounced, because you have no permission to send
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on behalf of example.com. The solution is that you map the address to
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your own domain, e.g.
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-SRS0+xxxx=yy=example.com=alice@yourdomain.org (forward SRS). If the
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+`SRS0+xxxx=yy=example.com=alice@yourdomain.org` (forward SRS). If the
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mail is bounced later and a notification arrives, you can extract the
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original address from the rewritten one (reverse SRS) and return the
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notification to the sender. You might notice that the reverse SRS can
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-be abused to turn your server into an open relay. For this reason, xxxx
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-and yy are a cryptographic signature and a time stamp. If the signature
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+be abused to turn your server into an open relay. For this reason, `xxxx`
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+and `yy` are a cryptographic signature and a time stamp. If the signature
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does not match, the address is forged and the mail can be discarded.
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Building
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@@ -47,8 +47,11 @@ standard CMake flags. Use `-D<option>=<value>` to override the defaults.
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* `GENERATE_SRS_SECRET` (default: `ON`). Generate a random secret on install.
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* `USE_APPARMOR` (default: `OFF`): Install an AppArmor profile for the daemon.
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+* `USE_SELINUX` (default: `OFF`): Install an SELinux policy module for
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+ the daemon.
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* `INIT_FLAVOR` (default: auto-detect). Select the appriopriate startup
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- script type. Must be one of (`systemd`, `upstart`,`sysv-lsb`,`sysv-redhat`) or `none`.
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+ script type. Must be one of (`systemd`, `upstart`,`sysv-lsb`,`sysv-redhat`)
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+ or `none`.
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* `CHROOT_DIR` (default: `${CMAKE_INSTALL_PREFIX}/lib/postsrsd`). Chroot jail
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for the daemon.
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* `SYSCONF_DIR` (default: `/etc`). Location of system configuration files.
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@@ -56,6 +59,8 @@ standard CMake flags. Use `-D<option>=<value>` to override the defaults.
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the postsrsd settings.
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* `DOC_DIR` (default: `${CMAKE_INSTALL_PREFIX}/share/doc/postsrsd`). Install
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destination for documentation files.
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+* `SYSD_UNIT_DIR` (default: `${SYSCONF_DIR}/systemd/system`). Install
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+ destination for systemd startup files.
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Installing
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----------
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@@ -66,20 +71,25 @@ files.
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Configuration
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-------------
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-The configuration is located in `/etc/default/postsrsd` by default. You must store
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-at least one secret key in `/etc/postsrsd.secret`. The installer tries to generate
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-one from `/dev/urandom`. Be careful that no one can guess your secret,
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-because anyone who knows it can use your mail server as open relay!
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-Each line of `/etc/postsrsd.secret` is used as secret. The first secret is
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-used for signing and verification, the others for verification only.
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+The configuration is located in `/etc/default/postsrsd` by default. On many
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+systems, the default configuration will work out-of-the-box, but please take
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+the two minutes to check the settings for yourself. Also, please make sure
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+that Postfix has the correct domain name configured, i.e.
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+`postconf -h mydomain` returns the correct value.
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+You must store at least one secret key in `/etc/postsrsd.secret`. The installer
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+tries to generate one from `/dev/urandom`. Be careful that no one can guess
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+your secret, because anyone who knows it can use your mail server as open
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+relay! Each line of `/etc/postsrsd.secret` is used as secret. The first secret
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+is used for signing and verification, the others for verification only.
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PostSRSd exposes its functionality via two TCP lookup tables. The
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recommended Postfix configuration is to add the following fragment to
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your main.cf:
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- sender_canonical_maps = tcp:127.0.0.1:10001
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+ sender_canonical_maps = tcp:localhost:10001
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sender_canonical_classes = envelope_sender
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- recipient_canonical_maps = tcp:127.0.0.1:10002
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+ recipient_canonical_maps = tcp:localhost:10002
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recipient_canonical_classes= envelope_recipient,header_recipient
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This will transparently rewrite incoming and outgoing envelope addresses,
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Timo Röhling
8 years ago