openssh client hangs after SSH2_MSG_KEXINIT sent

Hi all. Can anyone shed some light why this is happening? I can connect
from other hosts except from this one. No firewalls or packet modifiers.
Thank you very much. 

$ ssh -vvv user@dev.domain.com
OpenSSH_4.3p2, OpenSSL 0.9.8b 04 May 2006
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug2: ssh_connect: needpriv 0
debug1: Connecting to dev.domain.com [X.X.X.X] port 22.
debug1: Connection established.
debug1: identity file /home/ruiwen/.ssh/identity type -1
debug1: identity file /home/ruiwen/.ssh/id_rsa type 1
debug1: identity file /home/ruiwen/.ssh/id_dsa type -1
debug1: Remote protocol version 2.0, remote software version
OpenSSH_4.2p1 Debian-7ubuntu3.1
debug1: match: OpenSSH_4.2p1 Debian-7ubuntu3.1 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_4.3
debug2: fd 3 setting O_NONBLOCK
debug1: SSH2_MSG_KEXINIT sent

Regards,
Marc

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