By using AWS re:Post, you agree to the Terms of Use

Questions tagged with Networking & Content Delivery

Sort by most recent

Browse through the questions and answers listed below or filter and sort to narrow down your results.

EC2 mysteriously loses connectivity - telnet google.com 80 not working - AMI on another EC2 works without problems

I have an ec2 instance on a public subnet with Ubuntu running for months without problems. Today, when connecting to it via ssh I have seen the following error: ``` Failed to connect to https://changelogs.ubuntu.com/meta-release-lts. Check your Internet connection or proxy settings ``` Investigating a little more in depth I see that a simple ``` telnet google.com 80 Trying 172.217.19.238... ``` does not work, it does not establish a connection. I have also tried ``` nslookup google.com Server: 127.0.0.53 Address: 127.0.0.53#53 Non-authoritative answer: Name: google.com Address: 172.217.19.238 Name: google.com Address: 2a00:1450:4007:80d::200e ``` and it works fine. A telnet to another instance of the same vpc and subnet works ok. The systemd-resolved.service is up and without errors: ``` systemctl status systemd-resolved.service ● systemd-resolved.service - Network Name Resolution Loaded: loaded (/lib/systemd/system/systemd-resolved.service; enabled; vendor preset: enabled) Active: active (running) since Tue 2022-08-23 10:37:22 UTC; 46min ago Docs: man:systemd-resolved.service(8) https://www.freedesktop.org/wiki/Software/systemd/resolved https://www.freedesktop.org/wiki/Software/systemd/writing-network-configuration-managers https://www.freedesktop.org/wiki/Software/systemd/writing-resolver-clients Main PID: 1586 (systemd-resolve) Status: "Processing requests..." Tasks: 1 (limit: 4637) Memory: 4.3M CGroup: /system.slice/systemd-resolved.service └─1586 /lib/systemd/systemd-resolved Aug 23 10:37:22 ip-172-31-34-169 systemd[1]: Starting Network Name Resolution... Aug 23 10:37:22 ip-172-31-34-169 systemd-resolved[1586]: Positive Trust Anchors: Aug 23 10:37:22 ip-172-31-34-169 systemd-resolved[1586]: . IN DS 20326 8 2 e06d44b80b8f1d39a95c0b0d7c65d08458e880409bbc683457104237> Aug 23 10:37:22 ip-172-31-34-169 systemd-resolved[1586]: Negative trust anchors: 10.in-addr.arpa 16.172.in-addr.arpa 17.172.in-addr> Aug 23 10:37:22 ip-172-31-34-169 systemd-resolved[1586]: Using system hostname 'ip-172-31-34-169'. Aug 23 10:37:22 ip-172-31-34-169 systemd[1]: Started Network Name Resolution. ``` I have created an AMI of this instance and I have raised another ec2 with this AMI, and everything works correctly, the new ec2 is in the same vpc and subnet and has the same security group, so I rule out connectivity problems in the vpc, route table , ACL, internet gateway etc... Could it be due to some problem in the network interface? Any idea what could be happening?
2
answers
0
votes
34
views
asked a month ago