Topic: exposing ports on a debian server

[tdelacour]

Hi all and thanks in advance.

I am trying to set up a simple apache server. Right now I'm stuck on the fact that I cannot access the server from the outside world. Say the host is named "a.b.c.d".

Here is what I can do:
ping a.b.c.d
ssh account@a.b.c.d
curl localhost (after ssh-ing into the host)

Here is what I cannot do:
curl a.b.c.d
curl a.b.c.d:80
curl a.b.c.d:443
(similar with telnet)

I am guessing that this means that ports 80 and/or 443 are not exposed, or publicly available on the internet. Unfortunately I don't have enough knowledge to understand specifically what this means and how to fix it.

Details about the machine:
- Debian Jessie
- Apache2 2.4.10
:~$ netstat -an | egrep 'Proto|LISTEN'
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 127.0.0.1:53 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:5432 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:953 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:3306 0.0.0.0:* LISTEN
tcp6 0 0 :::80 :::* LISTEN
tcp6 0 0 :::22 :::* LISTEN
tcp6 0 0 ::1:5432 :::* LISTEN
tcp6 0 0 ::1:953 :::* LISTEN
tcp6 0 0 :::443 :::* LISTEN
tcp6 0 0 :::32769 :::* LISTEN
tcp6 0 0 :::32770 :::* LISTEN

I can also provide config details for apache.

Also, small note: I have sudo access to this machine, but not root access. I read that this might be a problem with ports under 1024. If this is the case, that is OK because I really only need to have a couple of high-number ports open, which I am forwarding to the port 80 on some docker containers (also running apache). As it stands now, I cannot curl into those ports either, e.g. curl a.b.c.d:32769 does not work either.

Thanks and please let me know if I can clarify anything or provide additional information!

[James Blond]

By default debian doesn't block any port.
The question for internal access is if those names are in the /etc/hosts file aka local DNS.

Having sudo is like being root


What is the Listen set to in the apache config files?
Just plain Listen 80 and Listen 443 or are they bind to an IP adress?

you might also check the iptables with

sudo iptables -L

to see if the ports are blocked.