Ubuntu 18.04 setting up network on secondary interface
Solution 1
The problem is almost certainly related to you attempting to set a default gateway on the secondary interface.
It is important to always remember that the default gateway isn't really a property of an individual interface instead it is a route added to the route table. The 'default gateway' is the route that is used when no other more specific routes do not match a given destination. If you attempt to add two default gateways with the same metric, only one or the other will work.
Solution 2
The default gateway is the address of the router which will route packets for which you don't have routes defined already. About 99% of the time, this is the router which will provide your system access to the Internet. Any host will have exactly one of these (per protocol) in a normal configuration.
You've defined two, so one conflicts with and overrides the other. Because it is not your gateway to the Internet, you should remove it again.
Chris
PHP Developer for PR Agency trying my hand at all things.
Updated on September 18, 2022Comments
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Chris almost 2 years
I've got a VM running Ubuntu 18.04 - it's all setup and running on a single public IP and has two interfaces -
ens160
(public) &ens192
(private).My interface ens160 is already fully configured. However, when I try and setup
ens192
and apply the settings withnetplan apply
,ens160
stops pinging externally.ifconfig -
ens160: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 78.111.203.13 netmask 255.255.255.224 broadcast 78.111.203.31 inet6 fe80::250:56ff:feb2:ac74 prefixlen 64 scopeid 0x20<link> ether 00:50:56:b2:ac:74 txqueuelen 1000 (Ethernet) RX packets 8761053 bytes 3882588408 (3.8 GB) RX errors 0 dropped 242551 overruns 0 frame 0 TX packets 10449256 bytes 4654699595 (4.6 GB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 ens192: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet6 fe80::250:56ff:feb2:3d74 prefixlen 64 scopeid 0x20<link> ether 00:50:56:b2:3d:74 txqueuelen 1000 (Ethernet) RX packets 242552 bytes 14553120 (14.5 MB) RX errors 0 dropped 227391 overruns 0 frame 0 TX packets 7256 bytes 2349506 (2.3 MB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536 inet 127.0.0.1 netmask 255.0.0.0 inet6 ::1 prefixlen 128 scopeid 0x10<host> loop txqueuelen 1000 (Local Loopback) RX packets 9194 bytes 2309681 (2.3 MB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 9194 bytes 2309681 (2.3 MB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
Here's the configuration file
50-cloud-init.yaml
I'm attempting below -network: ethernets: ens160: addresses: - 78.111.203.13/27 gateway4: 78.111.203.1 nameservers: addresses: - 8.8.8.8 - 8.8.4.4 search: [] optional: true ens192: addresses: - 10.0.203.13/27 gateway4: 10.0.203.1 optional: true version: 2
As soon as I run
netplan try
, I can no longer ping my external IP78.111.203.13
until the timeout and the network resets itself. Interestingly though, I can still ping the external IP from other VM's within the network - I'm not sure if that means anything?The newly configured internal IP also begins pinging within the network - what I'd expect.
I hope you can help!
Chris.
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Zoredache almost 6 yearsDon't set a gateway. You can only have one default gateway.
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Chris almost 6 years@Zoredache - and it was as simple as that! Sir - you are a legend! Please feel free to add as the answer :)
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Chris almost 6 years@Zoredache - just a quick question though - how come it doesn't need a second gateway considering it's a completely separate interface?
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