Tag: ssh

Trying to become another user on Linux/getting error logging to server – su: cannot ser user id: Resource temporarily unavailable

emerson@linux:~ $ sudo su – oracle
sudo password for emerson:
su: cannot ser user id: Resource temporarily unavailable
emerson@linux:~ $

The number of processes for the user must have exceeded the soft limit. Change it to a higher number

root@linux:~ # vi /etc/security/limits.conf
oracle soft nproc 2047
oracle hard nproc 16384

Source: “cannot set user id: Resource temporarily unavailable” while trying to login or su as a local user in Red Hat Enterprise Linux

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Received disconnect from host: 2: Too many authentication failures for username

root@linux:~ # ssh emerson@10.32.36.45
Received disconnect from 10.32.36.45: 2: Too many authentication failures for emerson

The problem was that my server 10.32.36.45 tried to authenticate using a method and then gave up.

To fix it, edit file /etc/ssh/sshd_config and increase MaxAuthTries. On my server was just trying 1 time.

root@linux:~ # vi /etc/ssh/sshd_config
#MaxAuthTries 1

You can try to not use ssh keys to login but I commented the parameter to restore the default value and restarted the sshd service

root@linux:~ # service sshd restart
Stopping sshd: [ OK ]
Starting sshd: [ OK ]

SSH connection error – no supported authentication methods available (server sent keyboard-interactive)

Edit /etc/ssh/sshd_config and set the parameter PAMAuthenticationViaKBDInt to yes

# To disable tunneled clear text passwords, change PasswordAuthentication to no.
PasswordAuthentication yes

# Use PAM via keyboard interactive method for authentication.
# Depending on the setup of pam.conf(4) this may allow tunneled clear text
# passwords even when PasswordAuthentication is set to no. This is dependent
# on what the individual modules request and is out of the control of sshd
# or the protocol.
#PAMAuthenticationViaKBDInt no
PAMAuthenticationViaKBDInt yes

Received disconnect from host: 2: bind: Permission denied

I was receiving the error message Received disconnect from host: 2: bind: Permission denied when trying to connect using ssh.

Received disconnect from 172.16.36.110: 2: bind: Permission denied

root@linux:~ # rpm -q openssh
openssh-4.2p1-18.38.3

root@linux:~ # cat /etc/*release
SUSE Linux Enterprise Server 10 (x86_64)
VERSION = 10
PATCHLEVEL = 2
LSB_VERSION=”core-2.0-noarch:core-3.0-noarch:core-2.0-x86_64:core-3.0-x86_64″

I solved this problem unchecking Allow agent forwarding
Allow Agent Forwarding

OpenSSH on Solaris 6, 7 and 8 error message: Couldn’t connect to PRNGD socket “/var/spool/prngd/pool”: Connection refused

If you tried to start sshd on Solaris and appeared an error message saying it couldn’t connect to PRNGD socket, you need to start this daemon first.

root@solaris6:/ # /etc/init.d/sshd start
Couldn’t connect to PRNGD socket “/var/spool/prngd/pool”: Connection refused
couldn’t read entropy commands file /usr/local/etc/ssh_prng_cmds: No such file or directory
ssh-rand-helper child produced insufficient data

Run /etc/init.d/prngd start and then start ssh again

root@solaris6:/ # /etc/init.d/prngd start

root@solaris6:/# /etc/init.d/sshd start

The daemon should be running now

root@solaris6:/ # ps -ef | grep ssh
root 19359 1 0 10:00:08 ? 0:00 /usr/local/sbin/sshd
root 19376 18089 0 10:00:13 pts/1 0:00 grep ssh

How to make public authentication work in SSH

After you set up the public key authentication in any Unix server, if it keeps asking for your password even after you put your public key in the ~/.ssh/authorized_keys file you need to check the file permissions.

To fix this problem, check if the owner and the file permission is set right on:
Home directory (700)
.ssh directory (700)
authorized_keys file (600)