ssh_exchange_identification: Connection closed by remote host

Question

OpenSSH_5.9p1 Debian-5ubuntu1, OpenSSL 1.0.1 14 Mar 2012
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: Applying options for *
debug2: ssh_connect: needpriv 0
debug1: Connecting to 178.xxx.xxx.xxx [178.xxx.xxx.xxx] port 22.
debug1: Connection established.
debug1: identity file /home/orangetux/.ssh/id_rsa type 1
debug1: Checking blacklist file /usr/share/ssh/blacklist.RSA-2048
debug1: Checking blacklist file /etc/ssh/blacklist.RSA-2048
debug1: identity file /home/orangetux/.ssh/id_rsa-cert type -1
debug1: identity file /home/orangetux/.ssh/id_dsa type -1
debug1: identity file /home/orangetux/.ssh/id_dsa-cert type -1
debug1: identity file /home/orangetux/.ssh/id_ecdsa type -1
debug1: identity file /home/orangetux/.ssh/id_ecdsa-cert type -1
ssh_exchange_identification: Connection closed by remote host

Via an admin panel I can access the logs and I see:

Mar  8 20:32:10 vmi11458 sshd[2334]: Set /proc/self/oom_adj to 0
Mar  8 20:32:10 vmi11458 sshd[2334]: refused connect from 82.xxx.xxx.xxx (82.xxx.xxx.xxx)

I've stopped the DenyHosts service. But I still cannot log in. How can I solve this?

Answer 1

By stopping the denyhosts service, you prevent new entries from being created in /etc/hosts.deny, but entries that are already there remain. You will need manually remove the IP from the hosts.deny folder. To prevent the IP from being added again, you need to whitelist it in the allowed-hosts file.

Answer 2

To debug this issue, check the following things:

1. Please double-check that the permission of your .ssh directory 700 and permissions of your .ssh/authorized_keys file must be 600.

2. Check the logs /var/secure/logs for knowing reason of connection close.