Setting up GNS3

tested on ubuntu


For the Cloud connection to work, make sure you’ve got a bridge already, in which eth0 is part of. Any bridge will do, it can be xenbr0 or virbr0, and validate with a VPCS. Here, when the Cloud connection was eth0 itself, the host was not reachable and strangely enough, it still did relay the traffic across the LAN, as the gateway was responding .o0O

For the NAT connection to work, make sure you’ve got the virbr0 bridge already in da place. See the KVM guide.


dpkg --add-architecture i386
add-apt-repository ppa:gns3/ppa
apt install gns3-gui gns3-iou gns3-server

non-root YES
non-root capture YES

we’ve got an issue with dynamips/amd64, we need the i386 flavor. last available was for eoan (

dpkg -l | grep dynamips
dpkg -r dynamips

dpkg -i dynamips_0.2.21-1~eoan1_i386.deb
apt-get -f install

make sure you’re compliant with all the KVM and Libvirt requirements (libvirt group and bridge-utils, for example)

and finally restart your user session for the group permissions to apply or hotfix as follows

newgrp wireshark

Ready to go

systemctl status gns3
systemctl restart gns3
systemctl enable gns3
netstat -lntup | grep 3080

as user


add the Libvirt bridge in da Cloud

right-click properties

show special ethernet interfaces
add virbr0

also tune the terminal

Edit > Preferences / Console applications

# gnome-terminal -t "%d" -e "telnet %h %p"
EDIT --> terminator -e "telnet %h %p" -T "%d"

Server mode

#apt install python3-setuptools python3-aiohttp python3-psutil python3-jsonschema git
mv -i gns3.service.systemd /lib/systemd/system/gns3.service

which gns3server
vi /lib/systemd/system/gns3.service

(switch to /usr/bin/gns3server)

systemctl daemon-reload

guests take a lot of space, use a large partition for that purpose

useradd --system -s /sbin/nologin -m -d /data/gns3 gns3
usermod -aG ubridge gns3
usermod -aG kvm gns3
grep gns3 /etc/group
grep gns3 /etc/passwd

systemctl enable gns3
systemctl start gns3
netstat -lntp | grep 3080
nmap -p 3080 localhost

Dynamips appliances

see gns3-appliances

DIY QEMU templates

see gns3-guests



RouterGods - Adding serial interfaces in GNS3

How to add serial port on C7200 router?

Cloud how to add serial interface?

A Comparison of GNS3 Terminal Applications

Use custom symbols in GNS3


Copyright © 2022 Pierre-Philipp Braun