From mboxrd@z Thu Jan  1 00:00:00 1970
From: ummeegge <ummeegge@ipfire.org>
To: development@lists.ipfire.org
Subject: Re: [PATCH] openvpn: Actually apply configured parameters
Date: Tue, 24 Nov 2020 16:19:54 +0100
Message-ID: <5b6f69b49ab121c153e26c46449371dfeb583991.camel@ipfire.org>
In-Reply-To: <20201020132825.8416-1-michael.tremer@ipfire.org>
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Hi Michael,
wanted to warm this up alittle :-) do you want to deliver this patch ?

Best,

Erik

Am Dienstag, den 20.10.2020, 13:28 +0000 schrieb Michael Tremer:
> OpenVPN is an absolute mess. The behaviour of configuration
> parameters has been changed over the time; default values have been
> changed over time; and it looks like nobody is actually testing
> anything any more.
>=20
> I have been spending hours today on figuring out why OpenVPN
> is so damn slow. On a Lightning Wire Labs IPFire Mini Appliance
> it achieves about 100 MBit/s in the default configuration when
> "openssl speed -evp aes-256-gcm" achieves over 3.5 GBit/s.
>=20
> Changing any of the cryptography parameters does not change
> anything. Throughput remains around 100 MBit/s.
>=20
> I finally set "cipher none" and "auth none" which disables
> encryption and authentication altogether but does not increase
> throughput. From here on it was absolutely clear that it was
> not a crypto issue.
>=20
> OpenVPN tries to be smart here and does its own fragmentation.
> This is the worst idea I have heard of all day, because that job
> is normally done best by the OS.
>=20
> Various settings which allow the user to "tune" this are grossly
> ineffective - let alone it isn't even clear what I am supposed
> to configure anywhere. Setting "fragment 1500" weirdly still
> does not convince openvpn to generate a packet that is longer
> than 1400 bytes. Who'd a thunk?
>=20
> There is a number of other parameters to set the MTU or which
> are related to it (tun-mtu, link-mtu, fragment, mssfix).
>=20
> On top of all of this we have two "bugs" in ovpnmain.cgi which
> are being fixed in this patch:
>=20
> 1) mssfix can be configured by the user. However, we always
> =C2=A0=C2=A0 enable it in openvpn. The default is on, we only add "mssfix"
> =C2=A0=C2=A0 which simply turns it on.
> =C2=A0=C2=A0 It is now being disabled when the user has chosen so in the
> =C2=A0=C2=A0 web UI. I do not know if this is backwards-compatible.
>=20
> 2) We cap the MTU (tun-mtu) at 1500 bytes when fragment is being
> =C2=A0=C2=A0 used. So it becomes pointless that the user can this and the
> =C2=A0=C2=A0 user is not being made aware of this when they hit the save
> =C2=A0=C2=A0 button.
> =C2=A0=C2=A0 This was added when we added path MTU discovery. Since that
> =C2=A0=C2=A0 did not work and was removed, we can remove this now, too.
>=20
> I archived a solid 500-600 MBit/s of goodput with these settings:
>=20
> * Disable mssfix
> * Set "fragment" to 0
> * Set MTU to 9000
>=20
> I am sure the MTU could be further increased to have bigger packets,
> but I did not test how badly this will affect latency of the tunnel.
>=20
> OpenVPN seems to only be able to handle a certain amount of packets
> a second - no matter what. With larger packets, the throughput of
> the tunnel increases, but latency might as well.
>=20
> Signed-off-by: Michael Tremer <michael.tremer(a)ipfire.org>
> Cc: Erik Kapfer <erik.kapfer(a)ipfire.org>
> Cc: Stefan Schantl <stefan.schantl(a)ipfire.org>
> ---
> =C2=A0html/cgi-bin/ovpnmain.cgi | 29 +++++++++--------------------
> =C2=A01 file changed, 9 insertions(+), 20 deletions(-)
>=20
> diff --git a/html/cgi-bin/ovpnmain.cgi b/html/cgi-bin/ovpnmain.cgi
> index e7bc505e7..e5bc45c1c 100644
> --- a/html/cgi-bin/ovpnmain.cgi
> +++ b/html/cgi-bin/ovpnmain.cgi
> @@ -280,14 +280,7 @@ sub writeserverconf {
> =C2=A0=C2=A0=C2=A0=C2=A0 print CONF "server $tempovpnsubnet[0] $tempovpnsub=
net[1]\n";
> =C2=A0=C2=A0=C2=A0=C2=A0 #print CONF "push \"route $netsettings{'GREEN_NETA=
DDRESS'}
> $netsettings{'GREEN_NETMASK'}\"\n";
> =C2=A0
> -=C2=A0=C2=A0=C2=A0 # Check if we are using mssfix, fragment and set the co=
rretct
> mtu of 1500.
> -=C2=A0=C2=A0=C2=A0 # If we doesn't use one of them, we can use the configu=
red mtu
> value.
> -=C2=A0=C2=A0=C2=A0 if ($sovpnsettings{'MSSFIX'} eq 'on')=20
> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0{ print CONF "tun-mtu 1500\n"; }
> -=C2=A0=C2=A0=C2=A0 elsif ($sovpnsettings{'FRAGMENT'} ne '' &&
> $sovpnsettings{'DPROTOCOL'} ne 'tcp')=20
> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0{ print CONF "tun-mtu 1500\n"; }
> -=C2=A0=C2=A0=C2=A0 else=20
> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0{ print CONF "tun-mtu $sovpnsett=
ings{'DMTU'}\n"; }
> +=C2=A0=C2=A0=C2=A0 print CONF "tun-mtu $sovpnsettings{'DMTU'}\n";
> =C2=A0
> =C2=A0=C2=A0=C2=A0=C2=A0 if ($vpnsettings{'ROUTES_PUSH'} ne '') {
> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0@temp =3D split(/\n/,$vpnsettings{'ROUTES_PUSH'});
> @@ -320,6 +313,8 @@ sub writeserverconf {
> =C2=A0=C2=A0=C2=A0=C2=A0 }
> =C2=A0=C2=A0=C2=A0=C2=A0 if ($sovpnsettings{MSSFIX} eq 'on') {
> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0print CONF "mssfix\n";
> +=C2=A0=C2=A0=C2=A0 } else {
> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0print CONF "mssfix 0\n";
> =C2=A0=C2=A0=C2=A0=C2=A0 }
> =C2=A0=C2=A0=C2=A0=C2=A0 if ($sovpnsettings{FRAGMENT} ne '' &&
> $sovpnsettings{'DPROTOCOL'} ne 'tcp') {
> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0print CONF "fragment $sovpnsettings{'FRAGMENT'}\n";
> @@ -975,7 +970,7 @@ unless(-d
> "${General::swroot}/ovpn/n2nconf/$cgiparams{'NAME'}"){mkdir
> "${General
> =C2=A0=C2=A0 if ($cgiparams{'MTU'} eq '') {$tunmtu =3D '1500'} else {$tunmt=
u =3D
> $cgiparams{'MTU'}};
> =C2=A0=C2=A0 print SERVERCONF "tun-mtu $tunmtu\n";
> =C2=A0=C2=A0 if ($cgiparams{'FRAGMENT'} ne '') {print SERVERCONF "fragment
> $cgiparams{'FRAGMENT'}\n";}=20
> -=C2=A0 if ($cgiparams{'MSSFIX'} eq 'on') {print SERVERCONF "mssfix\n"; };
> +=C2=A0 if ($cgiparams{'MSSFIX'} eq 'on') {print SERVERCONF "mssfix\n"; }
> else { print SERVERCONF "mssfix 0\n" };
> =C2=A0=C2=A0 }
> =C2=A0
> =C2=A0=C2=A0 print SERVERCONF "# Auth. Server\n";=20
> @@ -1074,7 +1069,7 @@ unless(-d
> "${General::swroot}/ovpn/n2nconf/$cgiparams{'NAME'}"){mkdir
> "${General
> =C2=A0=C2=A0 if ($cgiparams{'MTU'} eq '') {$tunmtu =3D '1500'} else {$tunmt=
u =3D
> $cgiparams{'MTU'}};
> =C2=A0=C2=A0 print CLIENTCONF "tun-mtu $tunmtu\n";
> =C2=A0=C2=A0 if ($cgiparams{'FRAGMENT'} ne '') {print CLIENTCONF "fragment
> $cgiparams{'FRAGMENT'}\n";}
> -=C2=A0 if ($cgiparams{'MSSFIX'} eq 'on') {print CLIENTCONF "mssfix\n"; };
> +=C2=A0 if ($cgiparams{'MSSFIX'} eq 'on') {print CLIENTCONF "mssfix\n"; }
> else { print CLIENTCONF "mssfix 0\n" };
> =C2=A0=C2=A0 }
> =C2=A0
> =C2=A0=C2=A0 # Check host certificate if X509 is RFC3280 compliant.
> @@ -2204,7 +2199,7 @@ if ($confighash{$cgiparams{'KEY'}}[3] eq
> 'net'){
> =C2=A0=C2=A0=C2=A0 if ($confighash{$cgiparams{'KEY'}}[31] eq '') {$tunmtu =
=3D '1500'}
> else {$tunmtu =3D $confighash{$cgiparams{'KEY'}}[31]};
> =C2=A0=C2=A0=C2=A0 print CLIENTCONF "tun-mtu $tunmtu\n";
> =C2=A0=C2=A0=C2=A0 if ($confighash{$cgiparams{'KEY'}}[24] ne '') {print CLI=
ENTCONF
> "fragment $confighash{$cgiparams{'KEY'}}[24]\n";}
> -=C2=A0=C2=A0 if ($confighash{$cgiparams{'KEY'}}[23] eq 'on') {print CLIENT=
CONF
> "mssfix\n";}
> +=C2=A0=C2=A0 if ($confighash{$cgiparams{'KEY'}}[23] eq 'on') {print CLIENT=
CONF
> "mssfix\n";} else { print CLIENTCONF "mssfix 0\n"; }
> =C2=A0=C2=A0=C2=A0 }
> =C2=A0=C2=A0=C2=A0 # Check host certificate if X509 is RFC3280 compliant.
> =C2=A0=C2=A0=C2=A0 # If not, old --ns-cert-type directive will be used.
> @@ -2285,15 +2280,7 @@ else
> =C2=A0=C2=A0=C2=A0=C2=A0 print CLIENTCONF "nobind\r\n";
> =C2=A0=C2=A0=C2=A0=C2=A0 print CLIENTCONF "dev tun\r\n";
> =C2=A0=C2=A0=C2=A0=C2=A0 print CLIENTCONF "proto $vpnsettings{'DPROTOCOL'}\=
r\n";
> -
> -=C2=A0=C2=A0=C2=A0 # Check if we are using fragment, mssfix and set MTU to=
 1500
> -=C2=A0=C2=A0=C2=A0 # or use configured value.
> -=C2=A0=C2=A0=C2=A0 if ($vpnsettings{FRAGMENT} ne '' && $vpnsettings{DPROTO=
COL} ne
> 'tcp' )
> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0{ print CLIENTCONF "tun-mtu 1500=
\r\n"; }
> -=C2=A0=C2=A0=C2=A0 elsif ($vpnsettings{MSSFIX} eq 'on')
> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0{ print CLIENTCONF "tun-mtu 1500=
\r\n"; }
> -=C2=A0=C2=A0=C2=A0 else
> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0{ print CLIENTCONF "tun-mtu $vpn=
settings{'DMTU'}\r\n"; }
> +=C2=A0=C2=A0=C2=A0 print CLIENTCONF "tun-mtu $vpnsettings{'DMTU'}\r\n";
> =C2=A0
> =C2=A0=C2=A0=C2=A0=C2=A0 if ( $vpnsettings{'ENABLED'} eq 'on'){
> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0print CLIENTCONF "remote $v=
pnsettings{'VPN_IP'}
> $vpnsettings{'DDEST_PORT'}\r\n";
> @@ -2383,6 +2370,8 @@ else
> =C2=A0=C2=A0=C2=A0=C2=A0 print CLIENTCONF "verify-x509-name
> $vpnsettings{ROOTCERT_HOSTNAME} name\r\n";
> =C2=A0=C2=A0=C2=A0=C2=A0 if ($vpnsettings{MSSFIX} eq 'on') {
> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0print CLIENTCONF "mssfix\r\=
n";
> +=C2=A0=C2=A0=C2=A0 } else {
> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0print CLIENTCONF "mssfix 0\r\n";
> =C2=A0=C2=A0=C2=A0=C2=A0 }
> =C2=A0=C2=A0=C2=A0=C2=A0 if ($vpnsettings{FRAGMENT} ne '' && $vpnsettings{D=
PROTOCOL} ne
> 'tcp' ) {
> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0print CLIENTCONF "fragment =
$vpnsettings{'FRAGMENT'}\r\n";



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