Re: First look

[Colin Percival <cperciva@tarsnap.com>]

On 07/04/11 14:51, Trevor Blackwell wrote:
> I'm setting up spiped to replace my current mesh of ssh -L between cloud
> servers.

Does this mean I can tell people that spiped is going to be running on
robots now?  Please please please? ;-)

> So far:
> 
>    - I wish it had a don't-fork option so I could run it from
> daemontools supervise.

Hmm, ok.  I guess that's easy enough to do... personally I'd want spiped
to not respawn if it died, since "daemon died" usually implies "someone is
trying to exploit a security vulnerability" and I don't believe in giving
people second chances.

Any preference for what letter I should use for the option?

>    - It should set OREUSEADDR on its source socket. Currently it exits
> with EADDRINUSE if you start it within 30 seconds of killing an old one.
> 
>      I expect to have to start new ones / kill old ones whenever I add /
> remove a backend server. So restart time matters.

Good point.  I had intended to do that but I forgot before getting around
to finding the relevant line of code.

>    - I don't understand the performance / security tradeoff of the -f
> option. 

The -f disables the Diffie-Hellman handshake.

By default:
 * spiped can do about 400 handshakes per second on a modern x86 CPU
 * if the shared keyfile is compromised, existing connections remain secure

With -f:
 * spiped can do over 10000 handshakes per second on a modern x86 CPU
 * if the shared keyfile is compromised, anyone who logged the initial
handshake will be able to decrypt and tamper with existing connections.

Either way, connections established *after* the shared keyfile is compromised
will not be secure, of course.

-- 
Colin Percival
Security Officer, FreeBSD | freebsd.org | The power to serve
Founder / author, Tarsnap | tarsnap.com | Online backups for the truly paranoid