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 ( 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.

$ 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         :
Summary     : MimeFilter
Description :


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/ 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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