Can't connect outside local subnet.

[Ken D'Ambrosio]

On 2019-11-26 15:42, bdushok at luzerne.edu wrote:

> Ken, 
> 
> I've just deleted one of the gateways.   The other didn't reappear immediately.   
> 
> I tried using netplan apply again and the second route reappeared.   I deleted it again to see if the problem reappears.   I'm going to look through my config to see if there is anything odd.

Yeah... something wonky, then.  That just shouldn't be happening. 
Curious to see what you dig up in the configs! 

-Ken 

> Thanks again for your reply! 
> Bob 
> 
> Bob Dushok
> Director of Enterprise Systems and Computer Labs
> Luzerne County Community College
> 
> 1-800-377-5222 ext 7327
> bdushok at luzerne.edu 
> 
>> ----- Original message -----
>> From: "Ken D'Ambrosio" <ken at jots.org>
>> Sent by: "ubuntu-users" <ubuntu-users-bounces at lists.ubuntu.com>
>> To: bdushok at luzerne.edu
>> Cc: ubuntu-users at lists.ubuntu.com
>> Subject: Re: Can't connect outside local subnet.
>> Date: Tue, Nov 26, 2019 10:01 AM
>> 
>> On 2019-11-26 09:14, bdushok at luzerne.edu wrote: 
>> 
>> * 
>> Ken,
>> 
>> Thanks for your reply.
>> 
>> I'm pinging by IP address to avoid any potential DNS problems.   I have been testing using two ping commands as follows:
>> ping 10.1.1.10
>> ping 8.8.8.8
>> 
>> When this problem is occurring both fail.   Both of these IP addresses are outside the subnet used by our DMZ servers (the Ubuntu servers).
>> 
>> I don't have IPv6 running.
>> 
>> Oddly, I do appear to have two default gateways:
>> root at libproxy:/etc/netplan# netstat -rn | grep "^0\.0\.0\.0"
>> 0.0.0.0         10.3.0.1        0.0.0.0         UG        0 0          0 ens160
>> 0.0.0.0         10.3.0.1        0.0.0.0         UG        0 0          0 ens160
>> 
>> Both are the same and correct.   I find it odd that two are present. 
>> 
>> That *is* odd -- I mean, any time you have multiple default gateways, something's probably not quite right, but two going to the same place is... weird.  In your shoes, as at least a datapoint, I'd probably do a
>> route del default gw
>> and see what happens.  That should delete *one* of the two.  I'm curious to see:
>> * If the second one comes back, and
>> * If the problem presents itself while you only have one default gateway.
>> 
>> Good luck!
>> 
>> -Ken
>> 
>> * 
>> Bob
>> 
>> Bob Dushok
>> Director of Enterprise Systems and Computer Labs
>> Luzerne County Community College
>> 
>> 1-800-377-5222 ext 7327
>> bdushok at luzerne.edu
>> 
>> * ----- Original message -----
>> From: "Ken D'Ambrosio" <ken at jots.org>
>> To: "Ubuntu user technical support, not for general discussions" <ubuntu-users at lists.ubuntu.com>
>> Cc: bdushok at luzerne.edu
>> Subject: Re: Can't connect outside local subnet.
>> Date: Tue, Nov 26, 2019 9:06 AM 
>> 
>> * On 2019-11-26 08:44, bdushok at luzerne.edu wrote:
>> 
>> * * "A device outside the subnet:" are you pinging by hostname or IP?
>> 
>> * * What, exactly, is the syntax of your ping?
>> 
>> * * Do you have IPv6 running?  (Most default to at least having the interfaces up.)  I'm not sure this is relevant, but when I put "connect: invalid argument" into Google, most of the top hits involved IPv6, which makes me wonder.
>> 
>> * I'd also be interested in seeing if you might have more than one default gateway: "netstat -rn | grep "^0\.0\.0\.0" would show that.
>> 
>> * -Ken
>> 
>> * Recently I've been encountering random problems where Ubuntu Server 18.04 can't connect to devices outside of it's subnet.    The default gateway shown within netstat -rn is accurate during the problem times but all connections outside of the subnet fail.   I haven't yet performed a packet capture to see what it shows.
>> 
>> * A ping to a device outside the subnet results in "connect: invalid argument".
>> 
>> * Executing netplan apply fixes the problem, but several hours later the problem returns.
>> 
>> * The servers with this problem have all had patches applied on November 16th and the problem appeared to occur after these patches.   The servers have been online for many months prior without this problem.
>> 
>> * Has anyone encountered this problem?    Any suggestions on how I can fix this problem?
>> 
>> * Thanks,
>> * Bob
>> 
>> --
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>> ubuntu-users at lists.ubuntu.com
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