Date: Sun, 02 Jul 2017 22:31:29 +0200 From: "Herbert J. Skuhra" <herbert@mailbox.org> To: Eugene Grosbein <eugen@grosbein.net> Cc: freebsd-net@FreeBSD.org Subject: Re: [Bug 220351] Path MTU discovery works only after resetting an internal interface MTU (mpd5, ng_nat, ipfw) Message-ID: <87eftytwbi.wl-herbert@mailbox.org> In-Reply-To: <878tk6ydwt.wl-herbert@mailbox.org> References: <bug-220351-2472@https.bugs.freebsd.org/bugzilla/> <bug-220351-2472-lCDWr8PCgb@https.bugs.freebsd.org/bugzilla/> <87r2xzaw30.wl-herbert@mailbox.org> <87bmp3x7eu.wl-herbert@mailbox.org> <59590064.1040700@grosbein.net> <87a84myitf.wl-herbert@mailbox.org> <59590FE6.7030109@grosbein.net> <878tk6ydwt.wl-herbert@mailbox.org>
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Herbert J Skuhra skrev:
> =
> Eugene Grosbein skrev:
>> =
>> 02.07.2017 22:11, Herbert J. Skuhra =D0=C9=DB=C5=D4:
>>> Eugene Grosbein skrev:
>>>> =
>>>> 02.07.2017 21:03, Herbert J. Skuhra wrote:
>>>>> Skype for Business (S4B) on Mac OS X 10.12.6 (Beta5) is actually
>>>>> trying to connect over IPv4. The connection fails until I lower M=
TU to
>>>>> 1440. After resetting MTU to 1500 and restarting S4B it connects =
fine
>>>>> for a while ('route -n get' default shows 1500). I use 'set iface=
>>>>> enable tcpmssfix' in mpd5.conf and I've tried:
>>>>> =
>>>>> - set iface mtu and set link mtu/mru/mrru in mpd5.conf
>>>>> - set scrub ... max-mss in pf.conf
>>>> =
>>>> Please show output of ifconfig command for external ng interface.
>>> =
>>> ng0: flags=3D88d1<UP,POINTOPOINT,RUNNING,NOARP,SIMPLEX,MULTICAST> m=
etric 0 mtu 1440
>>> inet6 fe80::XXX:XXXX:XXXX:XXXX%ng0 prefixlen 64 scopeid 0x7 =
>>> inet XX.XX.XX.XX --> XX.XX.XX.YY netmask 0xffffffff =
>>> nd6 options=3D21<PERFORMNUD,AUTO_LINKLOCAL>
>> =
>> 'set iface enable tcpmssfix' in mpd.conf should be enough for you.
>> =
>> Are you sure you have it in right point of the config?
>> This is critical for it to take effect. Please see mpd.conf.sample f=
or example.
>> =
>> Doesn't mpd complain of this command to its log?
> =
> No.
> =
>> Make sure you have 'log +iface +iface2' command in your mpd.conf,
>> restart mpd5 and scan its log for 'tcpmssfix'.
> =
> mpd: [B1] IFACE: Connecting tcpmssfix
> =
> But when I disable IPv6 on my network everything is working... even
> without tcpmssfix enabled.
> =
> Instead of enabling ipv6cp in mpd5 I've also tested with an IPv6 tunn=
el
> from HE... same issue. :-(
Hmm, adding "mtu#1440" to /etc/rtadvd.conf apperently fixes these
issues. Makes sense?
--
Herbert
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