![]() ![]() Users should secure access to their generated private key just like it is a secret. These keys offer strong configurable asymmetric encryption. In addition, SSH allows users to create a public and private key pair that can subsequently be used in place of a password. SSH connections can be established with only a username and password for authentication. It would be a significant failure if offensive operations infrastructure was compromised or even accessible to adversaries. This is especially true if the SSH server is internet accessible. Firewallīecause SSH facilitates remote control of a host, the SSH server should always be configure with firewall rules that whitelist connection from a specific host. The most common SSH client/server is the OpenSSH implementation and is the application used for all references in this post. Most Linux-based servers have a SSH server installed and both Windows and Linux have a built-in SSH client. This can also be accomplished by using the autossh command instead of an upstart job.SSH is a protocol that allows a user to remotely connect to a host and typically provides an interactive shell or command prompt that can further be leveraged to execute commands.Now if the ssh tunnels are killed, or the system is rebooted the tunnels should start back up automatically.Rsyslog-rssh-syslog-client start/running, process 9816 Make sure the old reverse ssh session has terminated start rsyslog-rssh-syslog-client # This service maintains a remote ssh reverse tunnel for syslog-ingĮxec sudo -u rsyslog-remote ssh -nN -R 50514::1514 This will contain our reverse ssh command, and be setup to be respawned automatically if the process should ever terminate.On the loghost, setup an upstart config file in the /etc/init directory called /etc/init/nf.Jan 8 23:21:07 syslog-client user: This is a Stupid Test\! In a second or two, the message should appear in the syslog file being tailed on the tail -f /var/log/syslog.You can change this with the -p logger "This is a Stupid Test\!" The default facility and level for the logger command is user notice.On the syslog client, send a test message to the syslog facility with the logger command.On the loghost, start a tail on the syslog file (or other file if you've configured logging to go tail -f /var/log/syslog.Add the following lines to the /etc/rsyslog.d/nf file.On the loghost, configure rsyslog to open up a TCP listener on the loghost side of our ssh reverse tunnel.The specifies to use TCP transport vice UDP.This line sends all syslog messages across the tunnel - *.*.Append the following line to /etc/rsyslog.d/nf or place it in a new file like /etc/rsyslog.d/nf.This will be the port that correseponds with the reverse tunnel that was opened up on the syslog client.On the syslog client, configure rsyslogd to send logs to a remote host over a tcp port.If the ssh public key authentication was setup properly, it should prompt you to accept the syslog clients key, and then just sit there quietly.On the loghost, create the reverse tunnel as the rsyslog-remote user.So, any packet that is sent to 127.0.0.1:50514 on the syslog client, will be encrypted by the reverse ssh session and be available to be read on port 1514 on the loghost. We'll originate a reverse ssh tunnel on the loghost that listens on port 50514 on the loopback interface (127.0.0.1 and ::1 ) on the client and empties out on our loghost on port 1514. ssh directory on the loghost to the syslog scp /home/rsyslog-remote/.ssh/id_rsa.pub On the syslog client, copy the rsyslog-remote user's loghost public key to the authorized_keys file for the rsyslog-remote userĬat /home/user/id_rsa.pub > /home/rsyslog-remote/.ssh/authorized_keysĬhown rsyslog-remote:rsyslog-remote /home/rsyslog-remote/.ssh/authorized_keysĬhmod 600 /home/rsyslog-remote/.ssh/authorized_keys Copy the rsyslog-remote user's public key from the. ![]() On both the syslog client and the loghost, create a public and private keypair for the rsyslog-remote user.This assumes that both systems sshd is configured to allow authtication with public keys. Make sure that the rsyslog-remote user's password is very hard to guess with tons of entropy.or better yet lock the account as we'll be using ssh keys for authentication.Ĭonfiguring ssh public key authentication.This user will be used for the ssh tunnel between the two systems. Create a user on both the syslog client and the loghost. ![]()
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