Posts Tagged ‘server options’

Few sshd server Security Tips that will improve your server security

Monday, May 2nd, 2011

On each and every newly installed Linux or FreeBSD server. I’m always very cautious about three configuration directives for the ssh server.
This are X11Forwarding , Protocol and PermitRootLogin

One needs to be very watchful about this three ones, as tuning the right values surely prevents the server from many of the security issues that might rise up with the SSH server.

Many Linuxes like Debian and Ubuntu comes with X11Forwarding yes e.g. (X11Forwarding) enabled by default, this is an useless option in most of the cases as the servers I do administrate does not run a X environment.

Some older Linux distributions I have dealt with has the ssh Protocol 1 enabled by default and therefore, whether I do inherit an old server I have to start administrating the first thing I do is to check if the /etc/ssh/sshd_config‘s Protocol 1 option is enabled and if it is enabled I disable it.

PermitRootLogin is also an option which I often turn off as logging in via remote ssh is potentially dangerous as root password might get sniffed.

In overall the 3 sshd option’s I do check out in /etc/sshd/sshd_config on each newly installed Linux server are:

X11Forwarding yes
PermitRootLogin yes
Protocol 1

I always change this three options in my /etc/sshd/sshd_config
to:

X11Forwarding no
PermitRootLogin no
Protocol 2

One other options sshd server options which is good to be tuned is:

LoginGraceTime 120

Decreasing it to:

LoginGraceTime 60

is generally a good idea.

Of course after the changes I do restart the ssh daemon in order for the new configuration to take place:

linux:~# /etc/init.d/sshd restart
...

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Posted in FreeBSD, Linux, System Administration | No Comments »

Few nginx.conf configuration options for Nginx to improve webserver performance

Tuesday, April 12th, 2011

Nginx server main logo with russian star
From my previous two articles How to install nginx webserver from source on Debian Linux / Install Latest Nginx on Debian and How to enable output compression (gzipfile content compression) in nginx webserver , I have explained how the Nginx server can be installed and configured easily.

As I’m continuing my nginx adventures this days, by trying to take the best out of the installed nginx server, I’ve found few configuration options, which does improve nginx’s server performance and thought it might be nice to share it here in hope that some other nginx novice might benefit out if them.
To setup and start using the options you will have of course to place the conf directives in /usr/local/nginx/conf/nginx.conf or wherever your nginx.conf is located.

The configuration options should be placed in nginx’s conf section which starts up with:

http {

Here are the configuration options useful in hastening my nginx’s performance:

1. General options nginx settings

## General Options
ignore_invalid_headers on;
keepalive_requests 2000;
recursive_error_pages on;
server_name_in_redirect off;
server_tokens off;

2. Connection timeout nginx settings

## Timeouts
client_body_timeout 60;
client_header_timeout 60;
keepalive_timeout 60 60;
send_timeout 60;
expires 24h;

3. server options for better nginx tcp/ip performance

## TCP options
tcp_nodelay on;
tcp_nopush on;

4. Increase the number of nginx worker processes

Somewhere near the beginning of nginx.conf file you should have the directive option:

worker_processes 1;

Make sure you change this option to:

worker_processes 4;

This will increase the number of spawned nginx worker processes in a way that more spawned threaded servers will await for client connections:

Being done with all the above settings, as a next step you have to restart the nginx server, in my case via the init script:

debian:~# /etc/init.d/nginx restart
Restarting nginx: nginx.

Now to check everything is fine with nginx and more specific that the worker_processes 4 options has taken place issue the command:

debian:~# ps axu |grep -i nginx|grep -v grep
root 20456 0.0 0.0 25280 816 ? Ss 10:35 0:00 nginx: master process /usr/local/nginx/sbin/nginx
nobody 20457 0.0 0.0 25844 1820 ? S 10:35 0:00 nginx: worker process
nobody 20458 0.0 0.0 25624 1376 ? S 10:35 0:00 nginx: worker process
nobody 20459 0.0 0.0 25624 1376 ? S 10:35 0:00 nginx: worker process
nobody 20460 0.0 0.0 25624 1368 ? S 10:35 0:00 nginx: worker process

Above you notice the 4 nginx processes running with user nobody, they’re the same configured worker_processes I just pointed out above.

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Posted in Linux, System Administration | 2 Comments »