Great Shuttle Service
Charly's Column – sshuttle

When he doesn't want to deal with OpenVPN version conflicts or congestion control problems during TCP tunneling, Charly catches a ride on sshuttle.
In untrustworthy networks, I let OpenVPN tunnel my laptop. There are certainly alternatives, and I would like to present a particularly simple one: sshuttle [1]. As the name suggests, the tool relies on SSH. The tunnel's endpoint is a leased root server, just like with OpenVPN. Sshuttle is very frugal. It only needs SSH access with user privileges on the server; root privileges are not necessary. Additionally, Python must be installed on the server – that's it.
This is because sshuttle loads and executes the required Python code on the server after the SSH connection is established. It also avoids version conflicts between server and client software. The following command is all it takes to set up the tunnel:
sudo sshuttle -r <User>@<Server>:<Port> 0/0
You can leave out the port number if it is the SSH standard port 22. The 0/0
means that Linux should direct all connections into the tunnel. However, this means that I cannot reach other devices in the local network. To keep the local LAN still visible, I define it as an exception using the -x
parameter:
sudo sshuttle -r --dns <User>@<Server> 0/0 -x 192.168.2.0/24
--dns
is included here. This means that DNS queries also run through the tunnel, which does not happen automatically. This is sshuttle's Achilles heel: It only transports TCP; ICMP and UDP do not pass through the tunnel, apart from DNS.
Congestion Alert
Whereas other VPN technologies work at packet level and rely on TUN/TAP devices, sshuttle works at session level. It assembles the TCP stream locally, multiplexes it over the SSH connection, while keeping the status, and splits it into packets again on the destination side.
This avoids the TCP-over-TCP problem which plagues other tools such as OpenVPN: TCP has an overload control (congestion control). The protocol defines a performance limit on the basis of dropped packets. If you tunnel TCP over TCP, you lose congestion control for the inner connection, which can lead to bizarre error patterns. Sshuttle is immune to the problem.
Verbose parameters can help if you do need to troubleshoot. Figure 1 shows a connection setup with -v
. With the verbose option, sshuttle is very long-winded, so I recommend redirecting the output to a file that can be evaluated in peace. My conclusions: Sshuttle is an excellent and simple VPN for people who can do without UDP and ICMP.

Infos
- sshuttle: https://github.com/apenwarr/sshuttle
Buy this article as PDF
(incl. VAT)
Buy Linux Magazine
Direct Download
Read full article as PDF:
Price $2.95
News
-
Another New Linux Laptop has Arrived
Slimbook has released a monster of a Linux gaming laptop.
-
Mozilla VPN Now Available for Linux
The promised subscription-based VPN service from Mozilla is now available for the Linux platform.
-
Wayland and New App Menu Coming to KDE
The 2021 roadmap for the KDE desktop environment includes some exciting features and improvements.
-
Deepin 20.1 has Arrived
Debian-based Deepin 20.1 has been released with some interesting new features.
-
CloudLinux Commits Over 1 Million Dollars to CentOS Replacement
An open source, drop-in replacement for CentOS is on its way.
-
Linux Mint 20.1 Beta has Been Released
The first beta of Linux Mint, Ulyssa, is now available for downloading.
-
Manjaro Linux 20.2 has Been Unleashed
The latest iteration of Manjaro Linux has been released with a few interesting new features.
-
Patreon Project Looks to Bring Linux to Apple Silicon
Developer Hector Martin has created a patreon page to fund his work on developing a port of Linux for Apple Silicon Macs.
-
A New Chrome OS-Like Ubuntu Remix is Now Available
Ubuntu Web looks to be your Chrome OS alternative.
-
System76 Refreshes the Galago Pro Laptop
Linux hardware maker has revamped one of their most popular laptops.