Re: [PATCH v2 0/4] IPVS full NAT support + netfilter 'ipvs' match support

[Simon Horman <horms@verge.net.au>]

On Tue, Sep 29, 2009 at 02:35:15PM +0200, Hannes Eder wrote:
> The following series implements full NAT support for IPVS.  The
> approach is via a minimal change to IPVS (make friends with
> nf_conntrack) and adding a netfilter matcher, kernel- and user-space
> part, i.e. xt_ipvs and libxt_ipvs.

Its a bit late in the day for me to review the code, but I have a few
quick comments.

> 
> Example usage:
> 
> % ipvsadm -A -t 192.168.100.30:80 -s rr
> % ipvsadm -a -t 192.168.100.30:80 -r 192.168.10.20:80 -m
> # ...
> 
> # Source NAT for VIP 192.168.100.30:80
> % iptables -t nat -A POSTROUTING -m ipvs --vaddr 192.168.100.30/32 \
> > --vport 80 -j SNAT --to-source 192.168.10.10
> 
> or SNAT-ing only a specific real server:
> 
> % iptables -t nat -A POSTROUTING --dst 192.168.11.20 \
> > -m ipvs --vaddr 192.168.100.30/32 -j SNAT --to-source 192.168.10.10

If the iptables rule is not in place does LVS just use
its old NAT behaviour?

> First of all, thanks for all the feedback.  This is the changelog for v2:
> 
> - Make ip_vs_ftp work again.  Setup nf_conntrack expectations for
>   related data connections (based on Julian's patch see
>   http://www.ssi.bg/~ja/nfct/) and let nf_conntrack/nf_nat do the
>   packet mangling and the TCP sequence adjusting.
> 
>   This change rises the question how to deal with ip_vs_sync?  Does it
>   work together with conntrackd?  Wild idea: what about getting rid of
>   ip_vs_sync and piggy packing all on nf_conntrack and use conntrackd?
> 
>   Any comments on this?

    That sounds like a reasonable suggestion.

    I think that ip_vs_sync came along before conntrackd
    and no one has given much thought to merging the functionality.

> - xt_ipvs: add new rule '--vportctl port' to match the VIP port of the
>   controlling connection, e.g. port 21 for FTP.  Can be used to match
>   a related data connection for FTP:
> 
>   # SNAT FTP control connection
>   % iptables -t nat -A POSTROUTING -m ipvs --vaddr 192.168.100.30/32 \
>   > --vport 21 -j SNAT --to-source 192.168.10.10
>   
>   # SNAT FTP passive data connection
>   % iptables -t nat -A POSTROUTING -m ipvs --vaddr 192.168.100.30/32 \
>   > --vportctl 21 -j SNAT --to-source 192.168.10.10
> 
> - xt_ipvs: use 'par->family' instead of 'skb->protocol'
> 
> - xt_ipvs: add ipvs_mt_check and restrict to NFPROTO_IPV4 and NFPROTO_IPV6
> 
> - Call nf_conntrack_alter_reply(), so helper lookup is performed based
>   on the changed tuple.
> 
> Changes to the linux kernel (rebased to next-20090925):
> 
> Hannes Eder (3):
>       netfilter: xt_ipvs (netfilter matcher for IPVS)
>       IPVS: make friends with nf_conntrack
>       IPVS: make FTP work with full NAT support
> 
> 
>  include/linux/netfilter/xt_ipvs.h |   25 +++++
>  include/net/ip_vs.h               |    2 
>  net/netfilter/Kconfig             |    9 ++
>  net/netfilter/Makefile            |    1 
>  net/netfilter/ipvs/Kconfig        |    4 -
>  net/netfilter/ipvs/ip_vs_app.c    |   43 ---------
>  net/netfilter/ipvs/ip_vs_core.c   |   37 -------
>  net/netfilter/ipvs/ip_vs_ftp.c    |  178 ++++++++++++++++++++++++++++++++---
>  net/netfilter/ipvs/ip_vs_proto.c  |    1 
>  net/netfilter/ipvs/ip_vs_xmit.c   |   30 ++++++
>  net/netfilter/xt_ipvs.c           |  187 +++++++++++++++++++++++++++++++++++++
>  11 files changed, 418 insertions(+), 99 deletions(-)
>  create mode 100644 include/linux/netfilter/xt_ipvs.h
>  create mode 100644 net/netfilter/xt_ipvs.c
> 
> 
> Changes to iptables (relative to 1.4.5):
> 
> Hannes Eder (1):
>       libxt_ipvs: user-space lib for netfilter matcher xt_ipvs
> 
>  configure.ac                      |   11 +
>  extensions/libxt_ipvs.c           |  365 +++++++++++++++++++++++++++++++++++++
>  extensions/libxt_ipvs.man         |   24 ++
>  include/linux/netfilter/xt_ipvs.h |   25 +++
>  4 files changed, 422 insertions(+), 3 deletions(-)
>  create mode 100644 extensions/libxt_ipvs.c
>  create mode 100644 extensions/libxt_ipvs.man
>  create mode 100644 include/linux/netfilter/xt_ipvs.h