SSH Protocol 2 between 9.x and 10.0 fails

[Brett Glass]

Everyone:

I'm making my first FreeBSD 10.0 server, and have been trying to 
use scp to copy files onto it from a machine running 9.1. However, 
for some reason, transfers only work if I specify the "-1" option 
on the command line. The same is true of interactive SSH sessions; 
I can't log into either machine from the other with SSH Protocol 2. 
Has anyone else noticed this incompatibility? Here's an excerpt 
from the "verbose" output from a failed scp session in which I 
attempted a file transfer from the 9.1 server to the 10.0 server:

debug1: identity file /root/.ssh/id_rsa type -1
debug1: identity file /root/.ssh/id_rsa-cert type -1
debug1: identity file /root/.ssh/id_dsa type -1
debug1: identity file /root/.ssh/id_dsa-cert type -1
debug1: identity file /root/.ssh/id_ecdsa type -1
debug1: identity file /root/.ssh/id_ecdsa-cert type -1
debug1: Remote protocol version 1.99, remote software version 
OpenSSH_6.4_hpn13v11 FreeBSD-20131111
debug1: match: OpenSSH_6.4_hpn13v11 FreeBSD-20131111 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_5.8p2 FreeBSD-20110503
debug1: SSH2_MSG_KEXINIT sent

...and then the transaction freezes until it times out.

Sometimes, even specifying "-1" doesn't fully clear up the 
problems; multi-file transfers via scp still stall.

The 9.x server has been fully updated to the latest patch version 
using freebsd-update(8). Anyone else seeing this?

--Brett Glass