[Bug 220351] Path MTU discovery works only after resetting an internal interface MTU (mpd5, ng_nat, ipfw)

[Herbert J. Skuhra]

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 MTU 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=88d1<UP,POINTOPOINT,RUNNING,NOARP,SIMPLEX,MULTICAST> metric 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=21<PERFORMNUD,AUTO_LINKLOCAL>

--
Herbert