The spiped secure pipe daemon
Spiped (pronounced "ess-pipe-dee") is a utility for creating symmetrically encrypted and authenticated pipes between socket addresses, so that one may connect to one address (e.g., a UNIX socket on localhost) and transparently have a connection established to another address (e.g., a UNIX socket on a different system). This is similar to 'ssh -L' functionality, but does not use SSH and requires a pre-shared symmetric key.
Spiped uses strong and well-understood cryptographic components: The initial key negotiation is performed using HMAC-SHA256 and an authenticated Diffie-Hellman key exchange over the standard 2048-bit "group 14"; following the completion of key negotiation, packets are transmitted encrypted with AES-256 in CTR mode and authenticated using HMAC-SHA256. The simplicity of the code — about 6000 lines of C code in total, of which under 2000 are specific to spiped (the rest is library code originating from kivaloo and Tarsnap) — makes it unlikely that spiped has any security vulnerabilities.
On the author's 2.5 GHz Intel Core 2 laptop, spiped operates at approximately 300 Mbps.
To set up an encrypted and authenticated pipe for sending email between two systems (in the author's case, from many systems around the internet to his central SMTP server, which then relays email to the rest of the world), one might run
dd if=/dev/urandom bs=32 count=1 of=keyfile spiped -d -s '[0.0.0.0]:8025' -t '[127.0.0.1]:25' -k keyfile
on a server and after copying keyfile to the local system, run
spiped -e -s '[127.0.0.1]:25' -t $SERVERNAME:8025 -k keyfile
at which point mail delivered via
localhost:25 on the
local system will be securely transmitted to port 25 on the server
(which is configured to relay mail which arrives from 127.0.0.1 but
not from other addresses).
You can also use spiped to protect SSH servers from attackers: Since data is authenticated before being forwarded to the target, this can allow you to SSH to a host while protecting you in the event that someone finds an exploitable bug in the SSH daemon -- this serves the same purpose as port knocking or a firewall which restricts source IP addresses which can connect to SSH. On the SSH server, run
dd if=/dev/urandom bs=32 count=1 of=/etc/ssh/spiped.key spiped -d -s '[0.0.0.0]:8022' -t '[127.0.0.1]:22' -k /etc/ssh/spiped.key
then copy the server's
~/.ssh/spiped_HOSTNAME_key on your local system and add
Host HOSTNAME ProxyCommand spipe -t %h:8022 -k ~/.ssh/spiped_%h_key
~/.ssh/config file. This will cause
HOSTNAME to automatically connect using the spipe client via
the spiped daemon; you can then firewall off all incoming traffic on
The spiped project
Development of spiped takes place in the spiped git repository.
spiped secure pipe daemon is discussed on the
email@example.com mailing list.
The following versions of spiped are available:
|Version||Release date||SHA256 hash|