Hello Slugadonia,
Of late, I have had an inordinate amount of new Linux System
Administrators querying me in regard to an easy listing of ports
available for forwarding through a firewall. Notwithstanding, due to
the recent inquiry by Mr. Brandt and of others today, I am urged to
introduce the following advice --
A wonderful aspect of Linux, for most distributions anyway, is a list of
all the services available for forwarding. This list is located in the
file, aptly called, /etc/services.
How can one determine ports from this fabulous file? The easiest way is
by firing up your favorite terminal (xterm/konsole/gnome-terminal, etc.
etc,) and employing the following command line example I used to help a
new sys admin today, when perplexed as to what port MySQL listens:
thelogan@bofh$ grep mysql /etc/services
mysql 3306/tcp
mysql 3306/udp
Keep in mind the facility of this command, as I preformed it as a
regular user, not as root! Now, lets use the same method to resolve a
similiar perplexity posed by Mr. Brandt from the SLUG list:
thelogan@bofh$ grep https /etc/services
https 443/tcp # http protocol over TLS/SSL
https 443/udp
Succinctly put, the information in /etc/services can be extremely
helpful to those setting up an out-of-the-box firewall. For the wizened
who remember the days when they had to add things to /etc/services, such
as sane etc., or who grok the intricacies of ipfwadm, this posting was
not meant for you, but it is intended explicitly for the newest bevy of
Linux Systems Adminstrators.
Like it or not, when you start using Linux, you start becoming a Systems
Administrator. I am well aware of the other tools available for system
inquiries, in regard to which ports are actually listening, but that is
the stuff of further posts.
Hope this was useful,
The Logan
-- 20:05:01 up 63 days, 22:16, 4 users, load average: 0.28, 0.32, 0.21 We are ready for any unforeseen event that may or may not occur. -- Al Gore ICQ: 72101412 AIM/MSN/Yahoo/Jabber: logantheclever Registered Linux User: 277727
----------------------------------------------------------------------- This list is provided as an unmoderated internet service by Networked Knowledge Systems (NKS). Views and opinions expressed in messages posted are those of the author and do not necessarily reflect the official policy or position of NKS or any of its employees.
This archive was generated by hypermail 2.1.3 : Fri Aug 01 2014 - 18:42:28 EDT