Re: IPv4 specific issue with USB tethering between my Debian laptop and my phone

[Vincent Lefevre <vincent@vinc17.net>]

On 2021-12-15 17:01:54 +0000, Tim Woodall wrote:
> On Wed, 15 Dec 2021, Vincent Lefevre wrote:
> > I've tried
> > 
> >  iptables -A FORWARD -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --clamp-mss-to-pmtu
> > 
> > and
> > 
> >  iptables -A FORWARD -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --set-mss 1024
> > 
> I think you possibly want -A OUTPUT rules too.

This doesn't change anything.

> And also ip6tables rules.

There are no issues with IPv6.

> If you're going via a firewall then you (usually) only need -A FORWARD
> But if you're trying to configure it on your laptop itself you probably
> need -A OUTPUT (and possibly -A INPUT).

I can't use -A INPUT:

# iptables -A INPUT -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --clamp-mss-to-pmtu
iptables v1.8.7 (nf_tables):  RULE_APPEND failed (Invalid argument): rule in chain INPUT

And similar error with "-I INPUT":

iptables v1.8.7 (nf_tables):  RULE_INSERT failed (Invalid argument): rule in chain INPUT

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