Hack and / - Lightning Hacks--SSH Strikes Back

In this third Lightning Hacks roundup, check out how to automate screen connections, build reverse tunnels and use the elusive SSH command line.
Adding SSH Tunnels on the Fly

A lesser-known feature of SSH is that you can enter an internal command-line mode in an existing session and add extra tunnels. Let's say you already have an SSH session open from admin1 to londonweb1, and now you want to add the reverse tunnel without having to log out. First, press ~C (that's the ~ character and then a capital C) to open the SSH command line. Then, you can add extra port-forwarding commands as though they were part of the original SSH command line. When you are done, simply press Enter to return to the regular shell:

ssh> -R 2222:seattleweb1:22
Forwarding port.


This also could be useful if you use regular SSH tunnels (the -L option) as a poor-man's VPN and realize that, for instance, you need to set up an extra VNC or RDP tunnel to a new server. When you use the SSH command line, you won't have to close and break any existing sessions you have.

Kyle Rankin is a Systems Architect in the San Francisco Bay Area and the author of a number of books, including The Official Ubuntu Server Book, Knoppix Hacks and Ubuntu Hacks. He is currently the president of the North Bay Linux Users' Group.


Kyle Rankin is a director of engineering operations in the San Francisco Bay Area, the author of a number of books including DevOps Troubleshooting and The Official Ubuntu Server Book, and is a columnist for Linux Journal.


Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.

when ye put lot o'

Anonymous's picture

when you put lot of information, why don't you make it readable... i' is not coo'.. it's just klutzy..

One Click, Universal Protection: Implementing Centralized Security Policies on Linux Systems

As Linux continues to play an ever increasing role in corporate data centers and institutions, ensuring the integrity and protection of these systems must be a priority. With 60% of the world's websites and an increasing share of organization's mission-critical workloads running on Linux, failing to stop malware and other advanced threats on Linux can increasingly impact an organization's reputation and bottom line.

Learn More

Sponsored by Bit9

Linux Backup and Recovery Webinar

Most companies incorporate backup procedures for critical data, which can be restored quickly if a loss occurs. However, fewer companies are prepared for catastrophic system failures, in which they lose all data, the entire operating system, applications, settings, patches and more, reducing their system(s) to “bare metal.” After all, before data can be restored to a system, there must be a system to restore it to.

In this one hour webinar, learn how to enhance your existing backup strategies for better disaster recovery preparedness using Storix System Backup Administrator (SBAdmin), a highly flexible bare-metal recovery solution for UNIX and Linux systems.

Learn More

Sponsored by Storix