Double hopping

From: Adrian Casey (
Date: 10/11/05

Date: Tue, 11 Oct 2005 20:45:05 +0930

I'd like to be able to detect and prevent double hopping.

For example, a user is logged into host-A. From host-A they log into
host-B. From host-B, they log into host-C. How do I detect this double
hopping and how can I prevent it?

The user may use telnet or ssh. I don't want to install a wrapper for
telnet and ssh nor mess with syslog configuration. I'd like to rely on the
native tools available on a standard UNIX system. If possible, I'd like to
gather as many details as possible when the situation occurs - eg hostname,
username, source and destination hostnames.

Adrian Casey
Alice Springs Linux User Group