Possible reasons for timeout when trying to access

Question

I cannot SSH into my instance - Operation timed out. What could be the reasons why, and what can I do to resolve it? Rebooting normally takes a long time to take effect, and might just makes things worst

UPDATE: It is not about permissions - i can log in normally just fine. I suspect it might be because of memory issues

Answer 1

For me it was the apache server hosted on a t2.micro linux EC2 instance, not the EC2 instance itself.

I fixed it by doing:

sudo su

service httpd restart

Answer 2

Building off @ted.strauss's answer, you can select SSH and MyIP from the drop down menu instead of navigating to a third party site.

Answer 3

If SSH access doesn't work for your EC2 instance, you need to check:

• Security Group for your instance is allowing Inbound SSH access (check: view rules).

If you're using VPC instance (you've VPC ID and Subnet ID attached to your instance), check:

1. In VPC Dashboard, find used Subnet ID which is attached to your VPC.
2. Check its attached Route table which should have 0.0.0.0/0 as Destination and your Internet Gateway as Target.

On Linux, you may also check route info in System Log in Networking of the instance, e.g.:

++++++++++++++++++++++++++++++++++++++Net device info+++++++++++++++++++++++++++++++++++++++
+--------+------+------------------------------+---------------+-------+-------------------+
| Device |  Up  |           Address            |      Mask     | Scope |     Hw-Address    |
+--------+------+------------------------------+---------------+-------+-------------------+
|   lo   | True |          127.0.0.1           |   255.0.0.0   |   .   |         .         |
|  eth0  | True |         172.30.2.226         | 255.255.255.0 |   .   | 0a:70:f3:2f:82:23 |
+--------+------+------------------------------+---------------+-------+-------------------+
++++++++++++++++++++++++++++Route IPv4 info+++++++++++++++++++++++++++++
+-------+-------------+------------+---------------+-----------+-------+
| Route | Destination |  Gateway   |    Genmask    | Interface | Flags |
+-------+-------------+------------+---------------+-----------+-------+
|   0   |   0.0.0.0   | 172.30.2.1 |    0.0.0.0    |    eth0   |   UG  |
|   1   |   10.0.3.0  |  0.0.0.0   | 255.255.255.0 |   lxcbr0  |   U   |
|   2   |  172.30.2.0 |  0.0.0.0   | 255.255.255.0 |    eth0   |   U   |
+-------+-------------+------------+---------------+-----------+-------+

where UG flags showing you your internet gateway.

For more details, check: Troubleshooting Connecting to Your Instance at Amazon docs.

Answer 4

Just reboot the Ec2 Instance once you applied Rules

Answer 5

To connect use ssh like so:

ssh -i keyname.pem [e-mail]

Where keyname.pem is the name of your private key, username is the correct username for your os distribution, and xxx.xx.xxx.xx is the public ip address.

When it times out or fails, check the following:

Security Group

Make sure to have an inbound rule for tcp port 22 and either all ips or your ip. You can find the security group through the ec2 menu, in the instance options.

Routing Table

For a new subnet in a vpc, you need to change to a routing table that points 0.0.0.0/0 to internet gateway target. When you create the subnet in your vpc, by default it assigns the default routing table, which probably does not accept incoming traffic from the internet. You can edit the routing table options in the vpc menu and then subnets.

Elastic IP

For an instance in a vpc, you need to assign a public elastic ip address, and associate it with the instance. The private ip address can't be accessed from the outside. You can get an elastic ip in the ec2 menu (not instance menu).

Username

Make sure you're using the correct username. It should be one of ec2-user or root or ubuntu. Try them all if necessary.

Private Key

Make sure you're using the correct private key (the one you download or choose when launching the instance). Seems obvious, but copy paste got me twice.

Answer 6

To enable ssh access from the Internet for instances in a VPC subnet do the following:

• Attach an Internet gateway to your VPC.
• Ensure that your subnet's route table points to the Internet gateway.
• Ensure that instances in your subnet have a globally unique IP address (public IPv4 address, Elastic IP address, or IPv6 address).
• Ensure that your network access control (at VPC Level) and security group rules (at ec2 level) allow the relevant traffic to flow to and from your instance. Ensure your network Public IP address is enabled for both. By default, Network AcL allow all inbound and outbound traffic except explicitly configured otherwise