{{tag>[linux serial ethernet]}}
=====Serial<->Ethernet convertor=====
  * OS: CentOS 6.5
  * Hardware: PC Engines APU

This proof of concept is a serial-to-ethernet converter. It uses one IP-address per serial port, not an IP port.

^ IP address ^ IP Port ^ serial connection ^
| 192.168.100.101 | 22 | ntp2 server |
| 192.168.100.102 | 22 | kvm host |
| 192.168.100.103 | 22 | nas |

====Configure virtual IP addresses====
  * Create **/etc/sysconfig/network-scripts/ifcfg-eth0:0** <code>DEVICE="eth0:0"
BOOTPROTO="none"
ONBOOT="yes"
IPADDR="192.168.100.101"
NETMASK="255.255.255.0"</code>
  * Create **/etc/sysconfig/network-scripts/ifcfg-eth0:1** <code>DEVICE="eth0:0"
BOOTPROTO="none"
ONBOOT="yes"
IPADDR="192.168.100.102"
NETMASK="255.255.255.0"</code>
  * Create **/etc/sysconfig/network-scripts/ifcfg-eth0:2** <code>DEVICE="eth0:0"
BOOTPROTO="none"
ONBOOT="yes"
IPADDR="192.168.100.103"
NETMASK="255.255.255.0"</code>
  * Restart networking <code>service network restart</code>
====Install and configure dropbear====
  * Install dropbear from EPEL repository: <code>yum install dropbear</code>
  * Make sure dropbear does not start automaticly <code>chkconfig dropbear off</code>
  * Generate host keys. <code>/usr/bin/dropbearkey -t rsa -f /etc/dropbear/dropbear_rsa_host_key
/usr/bin/dropbearkey -t dss -f /etc/dropbear/dropbear_dss_host_key
/usr/bin/dropbearkey -t ecdsa -f /etc/dropbear/dropbear_ecdsa_host_key</code>
  * Configure default OpenSSH daemon to listen only on management port. Edit **/etc/ssh/sshd_config** <code>ListenAddress 192.168.100.99</code>
  * Restart OpenSSH service. <code>service sshd restart</code>
====Install and configure minicom====
  * Install minicom: <code>yum install minicom</code>
  * Create NTP2 server config. **/etc/minirc.ntp2**<code>pu port             /dev/ttyUSB0
pu minit
pu mreset
pu mhangup</code>
  * KVM server config. Create **/etc/minirc.kvm**<code>pu port             /dev/ttyUSB1
pu minit
pu mreset
pu mhangup</code>
  * NAS config. Create **/etc/minirc.nas** <code>pu port             /dev/ttyUSB2
pu minit
pu mreset
pu mhangup</code>

====Create login script====
  * Create **/usr/local/bin/serial.sh** <code>#!/bin/bash
#disable ctrl-c ctrl-z
trap '' 2 20

connectto=`echo $SSH_CONNECTION | cut -d " " -f3`

case $connectto in
  192.168.42.27)
	/usr/bin/minicom ntp2
	;;
  192.168.42.28)
	echo "naar 28"
	;;
  *)
	echo "Connection problem to $connectto"
	exit 1
	;;
esac</code>
  * Make it executable <code>chmod +x /usr/local/bin/serial.sh</code>
  * Add the script to **/etc/shells**.
====Create user====
  * Add user serial: <code>useradd -G dialout -s /usr/local/bin/serial.sh serial</code>
  * Enter password: <code>passwd serial</code>

====Start SSH services====
You can also start a separate dropbear process per IP address.
  * Start dropbear SSHd services. <code>/usr/sbin/dropbear -g -p 192.168.100.101:22 -p 192.168.100.102:22 -p 192.168.100.103:22</code>

====Test====
  * Log in to the virtual IP addresses with user serial and test serial connections.