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Updated:July 22, 2021
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This document describes how to change the hostname that is called in the HELO banner associated with the Cisco Email Security Appliance (ESA).
Change the Hostname That the ESA Gives in the HELO Banner
When an end-user uses TELNET to connect to an ESA, the IP or hostname used presents an incorrect hostname when the HELO request is issued:
$ telnet 172.19.0.117 25 Trying 172.19.0.117... Connected to dhcp-172-19-0-117.example.com. Escape character is '^]'. 220 ironport.example.com ESMTP helo 250 ironport.example.com
Choose Network > IP Interfaces and click the name of the interface and change the Hostname field.
Note: Remember that there is a setting in the various mail flow policies that allows you to override the hostname form of the banner.
Submit and Commit your changes through the GUI.
Enter the interfaceconfig command and choose the configured interface you want to change the hostname on. You will need to edit the "Hostname" field when prompted.
(ironport.example) > interfaceconfig
Currently configured interfaces: 1. Management (172.19.0.117/24 on Management: ironport.example.com) 2. PrivateNet (172.19.1.117/24 on Data 1: ironport.example.com) 3. TestNet (172.19.2.117/24 on Data 2: ironport.example.com) Choose the operation you want to perform: - NEW - Create a new interface. - EDIT - Modify an interface. - GROUPS - Define interface groups. - DELETE - Remove an interface. > edit Enter the number of the interface you wish to edit. > 1 IP interface name (Ex: "InternalNet"): [Management]> IP Address (Ex: 192.168.1.2): [172.19.0.117]> Ethernet interface: 1. Data 1 2. Data 2 3. Management > Netmask (Ex: "255.255.255.0" or "0xffffff00"): [0xffffff00]> Hostname: [ironport.example.com]> newhostname.example
Return to the main CLI prompt and commit your changes.
Re-attempt the earlier TELNET session. You should see the updated hostname referenced in the HELO request:
$ telnet 172.19.0.117 25 Trying 172.19.0.117... Connected to dhcp-172-19-0-117.example.com. Escape character is '^]'. 220 newhostname.example ESMTP helo 250 newhostname.example
A change to the hostname of the appliance associated with the interface(s) should not be confused with the sethostname command. The sethostname command on the CLI is used only to identify the system at the CLI prompt. You must enter a fully-qualified hostname. The sethostname command sets the name of the Email Security appliance. For more information related to CLI commands, view the Command References for the version of AsyncOS that is deployed on the appliance.