Debian 9 networking issue

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xpd

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#245598 12-Feb-2019 12:06

What am I doing wrong.......

I install Debian 9, and all is well...... then I set the IP to static and all networking comes to a grinding halt. Cant ping etc.

So the settings I want : IP 192.168.1.215 Mask 255.255.255.0 GW 192.168.1.1

What have I missed/done wrong ? :)

Ive followed multiple guides and all give the same result.......

TIA

XPD / Gavin

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Dolts

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#2177112 12-Feb-2019 12:16

Did you rename ens33 to eth0?

muppet

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#2177113 12-Feb-2019 12:16

What does ip neigh show you (arp entries)

Do you have an arp 192.168.1.1?

xpd

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#2177118 12-Feb-2019 12:34

All I did was modify the interface to static and added the address/net/gw details. (As per every site I found)

IP neigh gives me :

XPD / Gavin

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xpd

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#2177119 12-Feb-2019 12:35

Dont think it matters, but the Debian install is on a HyperV session.

XPD / Gavin

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#2177120 12-Feb-2019 12:36

Do you have some sort of funky iptables rules? Because that looks like you should be able to ping your default GW just fine. No layer2 issue anyway, you have an ARP for it (assuming that MAC address is the correct MAC of your router)

What happens if you flush all the tables (iptables -F)

xpd

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#2177128 12-Feb-2019 13:00

No change........ I'll set it back to Dynamic config and do some more poking from that..... but yeah, everything is showing as being fine which is whats puzzled me. I know Im no Linux guru and my networking skills are so so but even so... :)

XPD / Gavin

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xpd

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#2177130 12-Feb-2019 13:05

Something weird going on....... changed it back, and still no network. Yet after the initial install, I had network.

Might try another distro.

XPD / Gavin

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#2177369 12-Feb-2019 21:33

Does ‘dmesg’ give any clues?

I’m suspicious that it might be something systemd related ... (that is just me though ... :-))

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#2177399 12-Feb-2019 22:58

So what traffic does tcpdump/tshark/wireshark capture? At that PC and at the router, if possible. Do the ping requests actually leave the Debian system? Does the router see them? Does it send replies? Does the Debian system see the reply packets at all?

alexx

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#2177404 12-Feb-2019 23:06

xpd:

All I did was modify the interface to static and added the address/net/gw details. (As per every site I found)

Interesting, here is the one that I was using on Debian 8 with static ip:

$ cat /etc/network/interfaces
# interfaces(5) file used by ifup(8) and ifdown(8)

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
allow-hotplug eth0
iface eth0 inet static
address 192.168.1.22
netmask 255.255.255.0
network 192.168.1.0
broadcast 192.168.1.255
gateway 192.168.1.1

# Include files from /etc/network/interfaces.d:
source /etc/network/interfaces.d/*.cfg

Now I've switched to a bridge interface with Debian 9 (mostly because it gave more flexibility for things like running VMs under KVM), something like this:

$ cat /etc/network/interfaces
# interfaces(5) file used by ifup(8) and ifdown(8)

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
allow-hotplug eth0
iface eth0 inet manual

auto br0
iface br0 inet static
address 192.168.1.22
netmask 255.255.255.0
network 192.168.1.0
broadcast 192.168.1.255
gateway 192.168.1.1
bridge_ports eth0
bridge_stp off
bridge_fd 0
bridge_maxwait 0

# Include files from /etc/network/interfaces.d:
source /etc/network/interfaces.d/*.cfg

Perhaps your config is fine and perhaps I didn't need 'network' and 'broadcast' in mine as I've seen a lot of examples with just 'address', 'netmask' and 'gateway', but it is one thing you could try (although I expect your problems are elsewhere).

Do you have any possibility of setting up static addresses in your DHCP server?

Then you can just configure your hosts as DHCP and do all your configuration in the DHCP server.

#include <standard.disclaimer>

alexx

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#2177406 12-Feb-2019 23:40

xpd:

Dont think it matters, but the Debian install is on a HyperV session.

I'm not familiar with HyperV, but if your Debian is a VM guest under VMware and others, you have to set the networking to Bridged (in the VMware or KVM in my case). There are some other options that will not work for static ip addresses in the VM Guest.

Like I said, I'm not familiar with HyperV, but I expect there is a setting somewhere. Some virtualisation software will have the default setting set to the one that won't use any more ip addresses in the host subnet (might be a NAT option). This appears to be the "keep the LAN administrator happy" default, but it won't work for static ip addresses in the guest.

#include <standard.disclaimer>