Installing the SecureCircle MIME Filter agent on Enterprise Linux
  • 19 May 2021
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Installing the SecureCircle MIME Filter agent on Enterprise Linux

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The SecureCircle MIME filter (sc-java-agent) is responsible for transparently replacing SecureCircle encrypted file attachments in MIME formatted messages with their decrypted version.

SMTP traffic will be internally re-routed through the MIME filter utilizing the system's firewall (iptables). By default, traffic going to port 12355 on the system's loopback adapter (127.0.0.1) will be redirected to the MIME filter on port 22355. The MIME filter will process the message, then send it to the upstream process listening on port 12355.

Installing Java

A Java runtime environment JRE will need to be installed. The MimeFilter agent will use the default java available in the system’s PATH.

The default system java-1.8.0-openjdk-headless package is sufficient.

$ sudo yum install java-1.8.0-openjdk-headless

An alternative version is available from the SecureCircle repository.
https://nexus-cdn.saas.securecircle.com/repository/securecircle-centos/jre-8u121-linux-x64.rpm

$ sudo yum install jre-8u121-linux-x64.rpm

Installing the agent

Install the MimeFilter v1.0.8 package with the rpm command:

$ rpm -ivh --nodeps MimeFilter-1.0.8-1.noarch.rpm

You can verify the package information and files installed with the rpm command:

$ rpm -qil MimeFilter
Name        : MimeFilter
Version     : 1.0.8
Release     : 1
Architecture: noarch
Install Date: Wed 19 May 2021 07:08:10 PM UTC
Group       : System Environment/Daemons
Size        : 5664243
License     : (c) 2018 Secure Circle, LLC
Signature   : (none)
Source RPM  : MimeFilter-1.0.8-1.src.rpm
Build Date  : Wed 12 Aug 2020 04:34:37 AM UTC
Build Host  : localhost
Relocations : (not relocatable)
Packager    : Secure Circle, LLC
Vendor      : Secure Circle, LLC
URL         : https://securecircle.com
Summary     : MimeFilter
Description :

/opt/securecircle/bin/MimeFilter-1.0.8-jar-with-dependencies.jar
/opt/securecircle/bin/MimeFilter.jar
/opt/securecircle/bin/sc-java-agent.sh
/opt/securecircle/temp
/usr/lib/systemd/system/sc-java-agent.service

Enabling the service

The MimeFilter package installs a systemd service to /usr/lib/systemd/system/sc-java-agent.service.

The service can be started with the command:

systemctl start sc-java-agent

It will not be started after package installation.

It can be enabled to start on boot with the command:

systemctl enable sc-java-agent

Verify the service is running with:

systemctl status sc-java-agent

Complete logs for the service can be viewed with:

journalctl -a -u sc-java-agent

Customizing iptables rules

Firewall rules for routing to the MimeFilter may need to be customized. This can be done by modifying the file /opt/securecircle/bin/sc-java-agent.sh. The service will need to be restarted after with:

systemctl restart sc-java-agent

Verify the rules have loaded correctly with:

iptables -t nat -L OUTPUT

Monitor traffic

In the default configuration traffic can be monitored for troubleshooting by using tcpdump:

$ sudo tcpdump -Ann -i lo tcp port 12355 or tcp port 22355 or tcp port 25

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