This simple how-to enables a secondary network card on an Ubuntu instance running Amazon AWS EC2.
It assumes a setup where the primary network card is in a private subnet, and the secondary network card is in a public subnet.
To use this, follow these steps:
- Create a script file
setupSecondNIC.shwith the below content
- chmod +x setupSecondNIC.sh
- Run the script
- qcp /tmp/51-<NIC>.yaml /etc/netplan (replace NIC with the name of the network card)
netplan applyto apply the configuration
You should now have an enabled secondary network card.
#!/bin/bash # # One line to give the program's name and a brief description. # Copyright (C) 2013 Jostein Elvaker Haande - aka tolecnal # # This program is free software; you can redistribute it and/or modify # it under the terms of the GNU General Public License as published by # the Free Software Foundation; either version 2 of the License, or # (at your option) any later version. # # This program is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the # GNU General Public License for more details. # # You should have received a copy of the GNU General Public License # along with this program; if not, see <http://www.gnu.org/licenses/>. # # # @Filename: test.sh # @Author: Jostein Elvaker Haande - aka tolecnal # @Email: [email protected] # @Website: http://tolecnal.net # @License: GPL2 # @Created: Fri 23 Oct 2020 15:10:21 UTC # @Last Change: Tue 03 Nov 2020 16:29:54 UTC # @Revision: 7 # # get MAC (need to retry this command until it gets a non-zero MAC) TOKEN=`curl -X PUT "http://169.254.169.254/latest/api/token" -H "X-aws-ec2-metadata-token-ttl-seconds: 21600"` CFS_ENI_INTERFACE="ens6" CFS_ENI_HWADDR="$(cat /sys/class/net/$CFS_ENI_INTERFACE/address 2>/dev/null)" CFS_NODE_IP="$(curl -H "X-aws-ec2-metadata-token: $TOKEN" -s -f http://169.254.169.254/latest/meta-data/network/interfaces/macs/$CFS_ENI_HWADDR/local-ipv4s)" # query instance metadata for network CFS_ENI_CIDR="$(curl -H "X-aws-ec2-metadata-token: $TOKEN" -s -f http://169.254.169.254/latest/meta-data/network/interfaces/macs/$CFS_ENI_HWADDR/subnet-ipv4-cidr-block)" CFS_ENI_CIDR_NETWORK="$(echo $CFS_ENI_CIDR | cut -d/ -f1)" CFS_ENI_CIDR_PREFIX="$(echo $CFS_ENI_CIDR | cut -d/ -f2)" CFS_ENI_ROUTER="$(( $(echo $CFS_ENI_CIDR_NETWORK | cut -d. -f4) + 1))" CFS_ENI_GATEWAY="$(echo $CFS_ENI_CIDR_NETWORK | cut -d. -f1-3).$CFS_ENI_ROUTER" # write out netplan yaml file cat << EOF > /tmp/51-$CFS_ENI_INTERFACE.yaml network: version: 2 renderer: networkd ethernets: $CFS_ENI_INTERFACE: addresses: - $CFS_NODE_IP/$CFS_ENI_CIDR_PREFIX dhcp4: no routes: - to: 0.0.0.0/0 via: $CFS_ENI_GATEWAY table: 1000 - to: $CFS_ENI_CIDR via: 0.0.0.0 scope: link table: 1000 routing-policy: - from: $CFS_NODE_IP table: 1000 EOF