Archive for the tag 'hosts'

SBDavid
Oct 16th, 2009

Scanning Hosts with Nmap for vulnerability assessment

Scanning Hosts with Nmap for vulnerability assessment.

Using Nmap

Nmap can be run from a shell prompt by typing the nmap command followed by the hostname or IP address of the machine to scan.

nmap 192.168.0.10

Administrators can use Nmap on a network to find host systems and open ports on those systems.

Nmap is a popular tool included in Red Hat Enterprise Linux that can be used to determine the layout of a network. Nmap has been available for many years and is probably the most often used tool when gathering information. An excellent man page is included that provides a de-
tailed description of its options and usage.

Nmap is a competent first step in vulnerability assessment. You can map out all the hosts within your network and even pass an option that allows Nmap to attempt to identify the operating system running on a particular host.

# nmap 127.0.0.1

Starting Nmap 4.76 ( http://nmap.org ) at 2009-10-16 16:05 EDT
Interesting ports on localhost.localdomain (127.0.0.1):
Not shown: 996 closed ports
PORT STATE SERVICE
22/tcp open ssh
53/tcp open domain
3128/tcp open squid-http
3306/tcp open mysql

Nmap done: 1 IP address (1 host up) scanned in 0.32 seconds

For more information about using Nmap, refer to the official homepage at the following URL: http://www.insecure.org/

SBDavid
Sep 1st, 2009

Set users From addresses when my server hosts multiple virtual domains?

In Usermin’s Read Mail module, how can I set users’ From addresses when my server hosts multiple virtual domains?

By default, when a user composed email the From field contains username@systemhostname. This can be changed by following these steps :

Login to Webmin on the same server, and enter the Usermin Configuration module.

Click on Usermin Module Configuration.

Click on Read Mail.

In the Default hostname for From: addresses field, enter the domain or hostname that you want to appear after the @ in users’ From addresses.

If you want to stop users from changing their From address (to prevent mail forging), set the Allow editing of From: address option to No.

If you have multiple virtual domains and want different users to have different domains in their From addresses, you will need to set the

From: address mapping file to the name of a file that maps real email addresses to virtual domain email addresses.

This must be a text file, with each line containing :

username fromaddress

The username part of each line must be the user’s Usermin login, and the fromaddress is the new From address to assign to that user. The

username can also be the user’s full email address as it currently appears, such as joe@yourserver.com.