Remember the post where I mentioned /etc/services? Let’s talk more about that file.  It’s a list of all possible services you could run on your Linux® system, it doesn’t mean that your system is running those.

What port do web services use?  Well, web services are formally known as http, or HyperText Transport Protocol.  We’ll just call it http.   We can grep for http in /etc/services by:

Alpha:~ computerlamp$ grep http /etc/services

I got 105 lines back from that simple command.  I know that because I did this command when the first one scrolled a lot:

Alpha:~ computerlamp$ grep http /etc/services | wc -l

That’s a lot of ports.  Let’s pipe that command thorugh less and see what we get:

Alpha:~ computerlamp$ grep http /etc/services | less
#       http://www.iana.org/assignments/port-numbers
http             80/udp     www www-http # World Wide Web HTTP
http             80/tcp     www www-http # World Wide Web HTTP
http-mgmt       280/udp     # http-mgmt
http-mgmt       280/tcp     # http-mgmt
https           443/udp     # http protocol over TLS/SSL
https           443/tcp     # http protocol over TLS/SSL
gss-http        488/udp     # gss-http
gss-http        488/tcp     # gss-http
http-alt        591/udp     # FileMaker, Inc. - HTTP Alternate (see Port 80)
http-alt        591/tcp     # FileMaker, Inc. - HTTP Alternate (see Port 80)
http-rpc-epmap  593/udp     # HTTP RPC Ep Map
http-rpc-epmap  593/tcp     # HTTP RPC Ep Map
multiling-http  777/udp     # Multiling HTTP
multiling-http  777/tcp     # Multiling HTTP
netconfsoaphttp 832/tcp     # NETCONF for SOAP over HTTPS
netconfsoaphttp 832/udp     # NETCONF for SOAP over HTTPS
llsurfup-http   1183/udp    # LL Surfup HTTP
llsurfup-http   1183/tcp    # LL Surfup HTTP
llsurfup-https  1184/udp    # LL Surfup HTTPS
llsurfup-https  1184/tcp    # LL Surfup HTTPS
compaq-https    2381/udp    # Compaq HTTPS

The first line is a comment and that points us to the website that has all the registered ports.

The second line is the UDP port for HTTP, which is port 80.  TCP uses the same port.  That’s the basic port that all web traffic goes over, unless it is encrypted.  If it’s encrypted, it uses port 443.  That’s what this sentence means ‘http protocol over TLS/SSL’, it means ‘http traffic that’s encrypted’.