From: Florian Westphal <fw@strlen.de>
To: folkert <folkert@vanheusden.com>
Cc: Florian Westphal <fw@strlen.de>, netdev@vger.kernel.org
Subject: Re: masquerading AFTER first packet
Date: Thu, 2 Sep 2021 22:07:36 +0200 [thread overview]
Message-ID: <20210902200736.GB23554@breakpoint.cc> (raw)
In-Reply-To: <20210902174845.GE3350910@belle.intranet.vanheusden.com>
folkert <folkert@vanheusden.com> wrote:
> > You might want to try and disable udp releated offload settings to see
> > if that helps.
>
> If offloading is the problem, wouldn't the first packet fail as well?
No, not necessarily, I recall a bug with fraglist udp where only first
packet in the batch had headers changed.
[..]
> udp 17 119 src=185.243.112.54 dst=37.34.63.177 sport=52775 dport=161 packets=4 bytes=267 src=192.168.4.2 dst=185.243.112.54 sport=161 dport=52775 packets=1 bytes=80 [ASSURED] mark=0 use=1
> udp 17 119 src=185.243.112.54 dst=37.34.63.177 sport=52775 dport=161 packets=5 bytes=334 src=192.168.4.2 dst=185.243.112.54 sport=161 dport=52775 packets=1 bytes=80 [ASSURED] mark=0 use=1
> udp 17 119 src=185.243.112.54 dst=37.34.63.177 sport=52775 dport=161 packets=6 bytes=401 src=192.168.4.2 dst=185.243.112.54 sport=161 dport=52775 packets=1 bytes=80 [ASSURED] mark=0 use=1
> udp 17 119 src=185.243.112.54 dst=37.34.63.177 sport=52775 dport=161 packets=7 bytes=468 src=192.168.4.2 dst=185.243.112.54 sport=161 dport=52775 packets=1 bytes=80 [ASSURED] mark=0 use=1
> udp 17 118 src=185.243.112.54 dst=37.34.63.177 sport=52775 dport=161 packets=7 bytes=468 src=192.168.4.2 dst=185.243.112.54 sport=161 dport=52775 packets=1 bytes=80 [ASSURED] mark=0 use=1
> ...
>
> So yes, increating packet/byte counters.
[..]
> [Thu Sep 2 19:40:54 2021] nf_ct_proto_17: bad checksum IN= OUT= SRC=192.168.4.2 DST=185.243.112.54 LEN=82 TOS=0x00 PREC=0x00 TTL=64 ID=0 DF PROTO=UDP SPT=161 DPT=56523 LEN=61
So reverse direction packets are deemed invalid and are thus not reverse-translated.
This is a bug, but not sure where. What driver/nic is feeding these
packets to stack?
sysctl net.netfilter.nf_conntrack_checksum=0
should make things "work".
next prev parent reply other threads:[~2021-09-02 20:07 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-01 20:42 masquerading AFTER first packet folkert
2021-09-02 16:26 ` Florian Westphal
2021-09-02 17:48 ` folkert
2021-09-02 20:07 ` Florian Westphal [this message]
2021-09-02 20:54 ` folkert
2021-09-05 8:39 ` folkert
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210902200736.GB23554@breakpoint.cc \
--to=fw@strlen.de \
--cc=folkert@vanheusden.com \
--cc=netdev@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.