Amazon EC2 instance can't update or use yum

Question 1

Looks like the host is having trouble contacting the yum server. Make sure the instance has outbound internet access (check security groups etc). If the instance is in a VPC and the security groups look good you may need to use a nat appliance or attach an elastic IP.

Good luck-

Question 2

If you have an S3 endpoint on your VPC then this will cause yum to fail as repo file is stored in S3. To fix this add the following policy to S3 VPC endpoint:

{
"Version": "2012-10-17",
"Statement": [
    {
        "Effect": "Allow",
        "Principal": "*",
        "Action": "*",
        "Resource": [
            "arn:aws:s3:::repo.eu-west-1.amazonaws.com",
            "arn:aws:s3:::repo.eu-west-1.amazonaws.com/*"
        ]
    }
]
}

Replace eu-west-1 with the relevant region code that your S3 endpoint is in.

Question 3

A lot of first time users of Amazon EC2 run into this issue. In my experience, it's usually the result of not setting the allowed outgoing connections on their instance's security group. The tutorial that Amazon has for configuring Amazon Linux instances only mentions setting the Incoming connections so it's easy to forget that you never set the allowed outgoing ones. Simply allowing HTTP and HTTPS requests to any IP Address should fix the issue.

Question 4

I have the same problem and was related to name resolution. I used the following to correct:

EC2 instance has no public DNS

This is the good explanation from Mat:

Go to console.aws.amazon.com
Go To Services -> VPC
Open Your VPCs
select your VPC connected to your EC2 and
Edit Summary ---> Change DNS hostnames: to YES

Question 5

just assign the default security group along with the one you may have created. This solved my problem. ;)

Question 6

Check if your outbound entries are deleted/modified from assigned Security group. Normally Outbound entries are set to "All traffic" and allow any IP.

In my case, outbound was deleted. I again set to "All traffic" and it works.

Question 7

I had the same problem and the way I solved it, was by allowing inbound traffic for the HTTPS protocol port 443 on the security group of your NAT instance. Most of the repositories use HTTPS protocol. Make sure you haven't missed this.

Question 8

I had the same problem, turns out another sysadmin decided to route outbound internet traffic through a proxy. I found this by noticing some wearied proxy env settings, dug a little deeper, and then noticed an entry in my /etc/yum.conf file.

Commented out the proxy= line and all worked again.

[main]
cachedir=/var/cache/yum/$basearch/$releasever
keepcache=0
debuglevel=2
logfile=/var/log/yum.log
exactarch=1
obsoletes=1
gpgcheck=1
plugins=1
installonly_limit=5
bugtracker_url=http://bugs.centos.org/set_project.php?project_id=23&ref=http://bugs.centos.org/bug_report_page.php?category=yum
distroverpkg=centos-release
#proxy=http://pos-proxy-in-my-way-of-doing-actual-real-work:666

Question 9

With chadneal's comment. It is necessary to set the DNS Resolution to Yes.

Go to console.aws.amazon.com
Go To Services -> VPC
Open Your VPCs
Select your VPC connected to your EC2
Click Edit DNS Resolution and set it Yes

Question 10

I was getting the same exact error message for yum as described in the question. In my case I had a NACL that allowed all outgoing traffic but restricted incoming traffic to HTTP/HTTPS, SSH and All ICMP. Since NACLS are stateless attempting to run yum failed as incoming ephemeral connections that yum uses were not explicitly allowed and were therefore dropped.

Question 11

Loaded plugins: priorities, update-motd, upgrade-helper Could not retrieve mirrorlist http://repo.us-east-1.amazonaws.com/latest/main/mirror.list error was 12: Timeout on http://repo.us-east-1.amazonaws.com/latest/main/mirror.list: (28, 'Connection timed out after 10001 milliseconds')

One of the configured repositories failed (Unknown), and yum doesn't have enough cached data to continue. At this point the only safe thing yum can do is fail. There are a few ways to work "fix" this:

Contact the upstream for the repository and get them to fix the problem.
Reconfigure the baseurl/etc. for the repository, to point to a working upstream. This is most often useful if you are using a newer distribution release than is supported by the repository (and the packages for the previous distribution release still work).
Disable the repository, so yum won't use it by default. Yum will then just ignore the repository until you permanently enable it again or use --enablerepo for temporary usage:
```
yum-config-manager --disable <repoid>
```
Configure the failing repository to be skipped, if it is unavailable. Note that yum will try to contact the repo. when it runs most commands, so will have to try and fail each time (and thus. yum will be be much slower). If it is a very temporary problem though, this is often a nice compromise:
```
yum-config-manager --save --setopt=<repoid>.skip_if_unavailable=true
```

Cannot find a valid baseurl for repo: amzn-main/latest

Same error I was also having from last week tried almost everything but not able to install server and start httpd service.

Resolved it by just allowing all traffic IN/OUT to and From Security Group and NACL... try it it will be resolved defiantly.

Question 12

If you're using NACL on the subnet were the EC2 is located.

Quick fix

You will have to open inbound Ephemeral ports for this yum update.

For example adding the #100 inbound rule below:

Notice that this is still necessary even if the outbound rules allow all traffic:

Why did have to do this?

When yum opens an outbound connection on ports like 80/443 it comes back at a random high port (Ephemeral port).
Network ACLs are stateless (not like Security groups) and will not allow returned connection on the same port by default.

You can read more in here.

Question 13

Check internet connectivity on your EC2 instance by pinging

ping google.com

You will get response by if you have working internet there. If not then go to etc/resolv.conf file and add below lines in that file:

nameserver 8.8.8.8 nameserver 1.1.1.1 nameserver 1.0.0.1

Now check if internet is working. If yes, you can easily resume you work!!!!

Question 14

Also, if you are unable to get any DNS working, check your DHCP options set. I had left an old one in place, and when I cleaned up a project involving active directory integrations, it broke. The answer is simply to change back to the original/saved options.

Question 15

The problem can occur at both levels Security Groups and NACLs. In my case, I figured out that even after modifying the security group, the update failed. However, when the NACLs were modified.. the update was successful

Question 16

I ran the following command with sudo (can't do yum alone if you're not root) and it fixed the issue.

yum-config-manager --save --setopt=dev.mysql.com_downloads_repo_yum_.skip_if_unavailable=true

Question 17

I had the same problem. In my case, I mistakenly deleted the outbound rules of my security group. Adding outbound rule to allow all traffic solved the problem.

Question 18

please follow the below step

Step 1 : go to AWS-VPC

Step 2 : find DHCP option

Step 3 : if you dont have any DHCP options create a new DHCP

Step 4 : add domaine name = ap-south-1.compute.internal (if your using other region please use other regionname)

Step 5 : add domain name server = AmazonProvidedDNS

Step 6 : then select your VPC --> actions -->edit your DHCP option set --> Select DHCP set which you just created --> Save

Step 7 : Then Reboot your Instance

Step 8 : Login Your Instance then Just type yum list installed --> It will defiantly give you the list of installed things

Thank you

Question 19

don't worry this is simple error. this is not connect internet also.

just to create new file with vi editor:

vi /etc/resolv.conf

nameserver 8.8.8.8
nameserver 8.8.4.4

and then type this to quit vi: :wq

Question 20

I am using the default VPC and DNS host resolution is enabled by default; wasn't my issue. I followed the advice to add the default security group and that resolved my issue.

Question 21

ACL in your vpc differs from the instances inbound or outbound rules. I see the vpc's acl get people every day multiple times.

Question 22

check for private hosted zone such as "eu-west-1.s3.eu-west-1.amazonaws.com" and make sure the EC2 has internet , for instance if your EC2 instance is in a private subnet you need to make sure your routes point to a nat gateway or instance.

Question 23

for me these helped, check

NACL
Security Groups
Routing table

Question 24

this problem is usually caused by not being able to connect to the internet.

Do the following basic test: ping google.com (ping google), if the answer is no, if you are not pinging it is simple, your server is not connecting to the internet.

To solve this, edit the resolv.conf (nano /etc/resolv.conf) when you open the file you will see that it is empty, in my case here I wrote these lines here:

; generated by /usr/sbin/dhclient-script
search ec2.internal
timeout options:2 attempts:5
name server 172.31.0.2

Do this on yours, save the file, and test the ping again on google.com, if it responds normally, you can run yum update -y and it will work.

Hope this helps.

Question 25

I experienced the very same issue but the problem was not my Security Group or NACL.

Background: I added a domain name via Route53. The domain name continues to be hosted with DiscountASP.net. The VPC was created manually (no wizard or default). I created a DHCP Option Set with my domain name and the 4 servers IP addresses given to me by Route53.

Analysis: First, I needed to prove that the problem was not the Security Group or the NACL. I did this by attatching the default DHCP Option Set to my new VPC. It worked! I could do the yum update and "curl http://www.google.com". No problem.

I then created a new DHCP Option Set using my domain name and the Google DNS Servers. 8.8.8.8 & 8.8.4.4 This also worked.

I then took 1 of the 4 DNS Servers IPs provided by Route 53 and used it with my domain name in a new DHCP Option Set. I ran a test and it failed. I repeated the same test with 2 of the remaining 4 DNS Servers IPs, creating two separate DHCP Option Sets. I ran tests and they both failed.

After checking the spelling of my domain name I could only conclude that the problem was the domain name servers.

Solution: Amazon Virtual Private Cloud User Guide (PDF page 222) Amazon DNS Server (Sub topic)

"When you create a VPC, we automatically create a set of DHCP options and associate them with the VPC. This set includes two options: domain-name-servers = AmazonProvidedDNS, and domain-name=domainname-for-your-region. AmazonProvidedDNS is an Amazon DNS server, and this option enables DNS for instances that need to communicate over the VPC's Internet gateway. The string AmazonProvidedDNS maps to a DNS server running on a reserved IP address at the base of the VPC IPv4 network range, plus two. For example, the DNS Server on a 10.0.0.0/16 network is located at 10.0.0.2."

From page 221: DHCP: domain-name-servers

Option Name Description "The IP addresses of up to four domain name servers, or AmazonProvidedDNS. The default DHCP option set specifies AmazonProvidedDNS. If specifying more than one domain name server, separate them with commas."

The IP addresses that its referring to are for external domain name servers (excluding the possibility you have created a custom DNS).

So I created my final DHCP Option Set using my domain name and domain-name-servers=AmazonProvidedDNS. It worked! By the way the VPC DNS Resolution = yes & DNS Hostname = no.

Question 26

Go to the security group for which EC2 is configured. And verify the below fields in its Inbound rules.If these below fields are not there then add it by clicking on button Edit inbound rules.

Type-: All traffic
Protocol-: All
Port range-: All
Destination-: 0.0.0.0/0

Hope this would resolve the issue.

Question 27

Hay! Here is perfect answer i found

go to outbound rules add

All Traffic

That's it