[tproxy] The future of tproxy

Balazs Scheidler bazsi at balabit.hu
Sat May 26 07:36:28 CEST 2007

On Fri, 2007-05-25 at 10:45 +0200, Nicholas George wrote:
> I was just reading the following post:
> http://news.gmane.org/find-root.php?message_id=%3c20070103163357.14635.37754.stgit%40nienna.balabit%3e
> regarding TPROXY Version 4. ie NOT using iptables NAT, but being able
> to bind to a non-local address.
> The approach discussed in the post looks and sounds good. How close is
> it to being ready for production use? Do you consider TPROXY Version 2
> (the current TPROXY) safe for production use?

tproxy2 has served us well in production use, so it is safe, however
maintaining tproxy2 into the future especially now as ip_conntrack has
been replaced with nf_conntrack, is getting more and more difficult.

So we think tproxy4 is the only sensible way to go forward. We do not
use tproxy4 in production environment yet, but lab testing was performed
and functionality-wise it is complete.

Patrick McHardy is debating two points in the original patchset:
  1) the modification of the routing code, which'd be possible by using
marks (which then might conflict with any other use of the marks)
  2) a modification of the input path, assigning the socket pointer

As we discussed internally, 2) can be implemented by a another socket
lookup, which might be slower but safer (and when using a proxy it does
not matter too much anyway), and we'll do what he asked to get tproxy4
merged to mainline. Then, we'll probably maintain the missing bits as a
separate patch for our own.

A new release of tproxy4 should be expected next week.

> What are your future plans for TPROXY? I noticed that there's no plan
> for NAT in ipv6tables, so are you looking to move away from a NAT
> approach? Are you considering migrating towards Network Channels?

We definitely want to move away from NAT, and we don't plan to migrate
towards network channels. (at least for now).


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