Ssh connection refused

Question

My raspberry pi randomly started refusing connections. After a reboot it allows connections, nothing has been changed in months with the config.

Here is the ssh -vvv output

OpenSSH_5.9p1 Debian-5ubuntu1.3, OpenSSL 1.0.1f 6 Jan 2014
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 192.168.1.21 [192.168.1.21] port 22.
debug1: Connection established.
debug3: Incorrect RSA1 identifier
debug3: Could not load "/home/matthew/.ssh/id_rsa" as a RSA1 public key
debug1: identity file /home/matthew/.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/matthew/.ssh/id_rsa-cert type -1
debug1: identity file /home/matthew/.ssh/id_dsa type -1
debug1: identity file /home/matthew/.ssh/id_dsa-cert type -1
debug1: identity file /home/matthew/.ssh/id_ecdsa type -1
debug1: identity file /home/matthew/.ssh/id_ecdsa-cert type -1ssh_exchange_identification: Connection closed by remote host

output of stat /home/matthew/.ssh/id_rsa

  File: ‘/home/matthew/.ssh/id_rsa’  
  Size: 1675            Blocks: 8          IO Block: 4096   regular file    
Device: 811h/2065d      Inode: 564404    Links: 1
Access: (0600/-rw-------)  Uid: ( 1000/ matthew)   Gid: ( 1000/ matthew)
Access: 2015-10-26 20:46:38.000000000 -0400
Modify: 2011-03-06 22:34:36.000000000 -0500
Change: 2011-03-06 22:34:36.000000000 -0500   
 Birth: -

output of stat /home/matthew/.ssh

  File: ‘/home/matthew/.ssh’  
  Size: 4096            Blocks: 8          IO Block: 4096   directory      
Device: 811h/2065d      Inode: 564461      Links: 2
Access: (0700/drwx------)  Uid: ( 1000/ matthew)   Gid: ( 1000/ matthew)
Access: 2015-10-27 11:14:03.000000000 -0400
Modify: 2015-09-04 11:55:54.000000000 -0400
Change: 2015-09-04 11:55:54.000000000 -0400 
 Birth: -

UPDATE

I found last night that ssh began refusing new connections while I had an active/functioning connection on going. I tried to open another ssh connection and it again was refused.

Answer 1

So I believe I found the culprit. I don't know why it had any effect on eth0 but when I used to have my pi connected via WiFi I had this script running.

while true ; do
    if ifconfig wlan0 | grep -q "inet addr:" ; then
        sleep 60
    else
        echo "Network connection down! Attempting reconnection."
        ifup --force wlan0
        sleep 10
    fi
    done

This resolved some dropped WiFi issues. I'm not sure why all of a sudden it started causing refused ssh connections, after almost a year of using the hard wired connection. But its been chugging along all day now and has not refused a single connection.

Answer 2

Possible fix:

Remove your ~/.ssh folder, this will reset all of ssh's settings.

sudo rm -Rf ~/.ssh

Answer 3

Can you clarify what does "randomly" mean?

1. It works after reboot for a while, and then it stops working forever

OR

2. After a while it sometimes works, sometimes does not.

I would check:

• is sshd running? $ ps aux | grep -i sshd
• what happens if you start / restart sshd? $ sudo service ssh start and/or $ sudo service ssh restart
• any significant entries in the following logs: /var/log/syslog, /var/log/auth.log that correlate to the connection failures ?