This applies to all platforms I use: MDK8.1, RH7.2, Win2k, MacOS 9.1/X
I have been using ssh for a number of years but this is the first time I have 
seen this.
Problem: When trying to ssh/scp to my box I get the following:
ssh_exchange_identification: Connection closed by remote host
--snip--
OpenSSH_3.0p1, SSH protocols 1.5/2.0, OpenSSL 0x0090602f
debug1: Reading configuration data /usr/local/etc/ssh_config
debug1: Seeding random number generator
debug1: Rhosts Authentication disabled, originating port will not be trusted.
debug1: restore_uid
debug1: ssh_connect: getuid 502 geteuid 0 anon 1
debug1: Connecting to localhost [127.0.0.1] port 22.
debug1: temporarily_use_uid: 502/0 (e=0)
debug1: restore_uid
debug1: temporarily_use_uid: 502/0 (e=0)
debug1: restore_uid
debug1: Connection established.
debug1: read PEM private key done: type DSA
debug1: read PEM private key done: type RSA
debug1: identity file /home/unixtool/.ssh/identity type -1
debug1: identity file /home/unixtool/.ssh/id_rsa type -1
debug1: identity file /home/unixtool/.ssh/id_dsa type -1
ssh_exchange_identification: Connection closed by remote host
debug1: Calling cleanup 0x8063a20(0x0)
--snip--
The logs only report a refused connect from <IP>
Reading the news and searching multiple groups, I only found this reference 
when dealing with tcpwrappers.  I am using the correct version of wrappers, I 
compiled OpeenSSH from source (no rpm), there were no errors during 
configure/make, my hosts.allow have : ssh sshd : ALL , but still nothing works.
I have reviewed the sshd_config, it's the same as all my other boxen. When 
using Putty from my windows box, I get the same error.  I have no problem 
ssh'ing to another client, no problems scp'ing to another client, etc.  Yes, 
sshd is running.