SSH hung with an OpenSSH_6.6.1p1 --> OpenSSH_5.8p2_hpn13v11

[Wu ShuKun]

   greeting!
   ssh connection failed by using a new version SSH to and old one.
Below is the symptoms which on a same network.
Connection is Okay with old version SSH
%ssh -V
OpenSSH_5.4p1 FreeBSD-20100308, OpenSSL 0.9.8q 2 Dec 2010
%ssh -v 10.41.172.19
OpenSSH_5.4p1 FreeBSD-20100308, OpenSSL 0.9.8q 2 Dec 2010
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Connecting to 10.41.172.19 [10.41.172.19] port 22.
debug1: Connection established.
debug1: identity file /home/wsk/.ssh/id_rsa type -1
debug1: identity file /home/wsk/.ssh/id_rsa-cert type -1
debug1: identity file /home/wsk/.ssh/id_dsa type -1
debug1: identity file /home/wsk/.ssh/id_dsa-cert type -1
debug1: Remote protocol version 2.0, remote software version
OpenSSH_5.8p2_hpn13v11 FreeBSD-20110503
debug1: match: OpenSSH_5.8p2_hpn13v11 FreeBSD-20110503 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_5.4p1 FreeBSD-20100308
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client aes128-ctr hmac-md5 none
debug1: kex: client->server aes128-ctr hmac-md5 none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
The authenticity of host '10.41.172.19 (10.41.172.19)' can't be established.
RSA key fingerprint is ab:81:83:79:6a:d8:29:23:a0:51:1d:e6:f0:aa:ce:d6.
Are you sure you want to continue connecting (yes/no)?
---
failed with Latest SSH:
% ssh -V
OpenSSH_6.6.1p1, OpenSSL 1.0.1l-freebsd 15 Jan 2015
% ssh -v 10.41.172.19
OpenSSH_6.6.1p1, OpenSSL 1.0.1l-freebsd 15 Jan 2015
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Connecting to 10.41.172.19 [10.41.172.19] port 22.
debug1: Connection established.
debug1: identity file /home/wsk/.ssh/id_rsa type -1
debug1: identity file /home/wsk/.ssh/id_rsa-cert type -1
debug1: identity file /home/wsk/.ssh/id_dsa type -1
debug1: identity file /home/wsk/.ssh/id_dsa-cert type -1
debug1: identity file /home/wsk/.ssh/id_ecdsa type -1
debug1: identity file /home/wsk/.ssh/id_ecdsa-cert type -1
debug1: identity file /home/wsk/.ssh/id_ed25519 type -1
debug1: identity file /home/wsk/.ssh/id_ed25519-cert type -1
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_6.6.1_hpn13v11 FreeBSD-20140420
debug1: Remote protocol version 2.0, remote software version
OpenSSH_5.8p2_hpn13v11 FreeBSD-20110503
debug1: match: OpenSSH_5.8p2_hpn13v11 FreeBSD-20110503 pat OpenSSH_5*
compat 0x0c000000
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client aes128-ctr hmac-md5 none
debug1: kex: client->server aes128-ctr hmac-md5 none
debug1: sending SSH2_MSG_KEX_ECDH_INIT
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
Connection closed by 10.41.172.19

any ideas?