There are a few ways to sort server security, but one of the major ways to harden your server is to secure SSH. On a default machine you login as root directly, on the default port. This means you are susceptible to brute force and all other sorts of attacks. What I am going to write about is a short and simple guide about how to secure your SSH and what this does. You don’t have to do all of these although I would deeply recommend doing the steps below.
1. Changing SSH Protocol

I guess a good place to start would be what are the differences between the two SSH protocols (1 and 2), as not many people know this. You don’t need to know, but I think that you should know the reasons you are doing this. I will try to cut the crap out of it and keep it simple. Basically SSH2 uses separate protocols for transport, authentication and connections, splitting all your data up making it just that little bit more secure. It also has stronger cryptographic integrity checks and has better encryption. Basically what I am trying to say (but in tech talk) is that this is one change you should always make. Now lets get on to making the change.

Step 1) Use nano, pico or vi (your favorite text editor) to open up /etc/ssh/sshd_config for editing

Step 2) Find the Line #Protocol 2,1

Step 3) Uncomment the line and change it to

Protocol 2

2. Changing the SSH port

This is what we like to call security by obscurity, it is one extra thing the hacker has to guess before he can get in, although practically a port scan would be able to find the port. However i have found that changing the port does stop a lot of brute force attacks from occurring.

NOTE: Make sure you add the port you want to use to the firewall AND/or add yourself to the allow list so you can connect to the port and don’t lock yourself out.

Step 1) Again open up /etc/ssh/sshd_config with your favourite editor

Step 2) Find the line #Port 22

Step 3) Uncomment the line and replace with the following (where port 2777 is a random, unused port)

Port 2777

NB: To find out if the port is being used use the comand lsof -i:portnumber eg lsof -i:2777

3. Disable Direct Root Login

Unlike the other steps we have used this requires a bit more than editing the config file, but its not hard so dont worry about it. Again this is a little of security by obscurity adding an extra layer the hacker/cracker has to get through if he wants access to your machine, making that bit harder.

A lot of other guides you will see will tell you to add a cPanel account etc etc, but lets just make it easier shall we.

Step 1) Type the following in SSH replacing username with a random username eg sekadmin

adduser sekadmin

Step 2) Now lets give sekadmin a password

passwd sekadmin

You will now be given a password prompt twice. Make sure the word is not a dictionary word, I would recommend looking at my password article for the best password.

Step 3) Now we need to give sekadmin, the correct privileges so he can su – to root.

Step 4) Open up /etc/group with your favorite text editor. Find the line that starts with “wheel” and add your username on at the end of the line. Then close and save the file.

Step 5) Now you will need to test the login works so create a NEW ssh session and try to connect using the username that you just created. Once logged in type “su -” and then the root password to see if that works. If it works everything went ok and you continue on to the next step

Step 6) Once again open up our favourite file /etc/ssh/sshd_config in your text editor

Step 7) Find the line #PermitRootLogin yes, uncomment it and change it to no.

Other Methods

There are also some other methods that you can use. One of the other methods I like to use is binding SSH to an IP. If you do this, the best thing to do is use a spare IP that is not being used by a website. This will offer the most security.

Another great thing to do is to disable password logins totally and use an ssh key. I will not write anything about that here, because it can be a blog post on its own for a rainy day

AFTER all changes

To make all your changes take effect you will have to restart ssh

service sshd restart

A common problem for many people is remembering their passwords and at the same time making it cryptic enough. I thought I would share my password “remembering” techniques with you, which will help you keep things secure. There are three main methods you can use and I will describe that below.

Rhythm/Pattern

Now it may sound weird to have rhythm in your password, but when you think about it, it isn’1 too strange. It is all about memory, and you are more likely to remember a password when it has some rhythm to it, that you can remember. For example remembering a password such as

sardines0012a

is not going to be easy. (At least I dont think so). Whereas if you have a password with rhythm/a pattern

sand00handx

its much easier to remember.

Words

Another method that can also be very easy to use is to remember a word and then add your birth date on the end. An example of this is

Seeksadmin1980

This is very effective and very easy to remember as its 2 very memorable facts. It is also pretty hard to guess unless you know what word I had use and what number (it doesnt have to be birthdate, it could be the date you ordered the server)

Pattern

Now this is my favorite and preferred method. This is also different to the pattern/rhythm method i described above. So what is it about? Well that’s pretty simple, you make a pattern on your key board. Here is an example

!@#$%67890

if you are very clever you will have noticed that is holding the shift key pressing 1 to 5 and then letting go of shift and pressing the rest of the numbers. It is very easy to remember as its just a pattern on the keyboard. It does not really require you to remember each number/letter just the pattern. The last example ill give is

zaqwsx.;[]‘/

Which is z -> q, w->x ,->[, ]->/. This type of password is pretty much impossible to guess, and yet in my opinion is one of the easiest to remember.

Other Tips

Vary the methods you use of remembering your passwords and of course vary the passwords you use. Whether its something simple such as changing 1 digit for each server or adding the server name on the end of the password, it is important that the servers have different passwords. If you have a secure password, this is one less way a hacker can gain access to your system.