Re: Strange ssh hangups, netbsd-9 GENERIC

[Louis Guillaume <louis%zabrico.com@localhost>]

On 3/18/21 12:37 PM, RVP wrote:
> On Thu, 18 Mar 2021, Louis Guillaume wrote:
>
> > Ok - i did something similar with "nc" and text files in /var/log. It 
> > is able to connect and transfer up to and no more that 6144 bytes 
> > before closing. This seems to be consistent with what I was seeing via 
> > ssh.
> >
> > Smaller files transfer completely, but anything larger than 6144b is 
> > truncated at exactly 6144b == 6k.
> >
> > After some reading, that seems to smell like some kind of MTU or maybe 
> > jumbo frame business. All systems here on on gigabit ethernet. Just a 
> > hunch. Maybe it's my switch.
>
> Try turning jumbo frames off--you don't really need it. Reboot the switch
> also.
>
> > I can't rule out the firewall (ipfilter) - but even if that is the 
> > cause, this would be unexpected behavior.
>
> Try a port (both on nc(1) and sshd) other than 22.
>
> -RVP

Hrmpf - looks like jumbo frames are already off...

wm1: flags=0x8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500

... also a tcpdump shows the largest packet size being 1500, so that all 
seems in order. It does show the sshd sending an unexpected "RST" packet 
right before the end, though...

    192.168.1.2.22 > 192.168.1.126.64517: Flags [R], cksum 0xbd47

... which leads me to think it's something with sshd now.