Want to know needed open ports for internet connection

Hi all!

I just have internet at home and i want to know the minimum numbers of
ports which must be open to my connection works properly.
a nmap localhost gives :
111/tcp open rpcbind
139/tcp open netbios-ssn
445/tcp open microsoft-ds
6000/tcp open X11

but did the ports 111, 139, 445 (which i know are vulnerable under
win... bip )
must be open?

I use the following script :
http://monmotha.mplug.org/firewall/index.php
for my firewall. Moreover when launching this, it gives :

Setting up drop chains chains: iptables: No chain/target/match by that
name
LDROP iptables: No chain/target/match by that name
LREJECT TREJECT iptables: No chain/target/match by that name
Setting up per-proto ACCEPT: iptables: No chain/target/match by that
name
TCPACCEPT iptables: No chain/target/match by that name

the others messages look good..

Thanks

Kennux, a french linux addict

On 20 Jan 2004 04:48:29 -0800, (E-Mail Removed) (kennux) wrote:

>Hi all!
>
>I just have internet at home and i want to know the minimum numbers of
>ports which must be open to my connection works properly.
>a nmap localhost gives :
>111/tcp open rpcbind
>139/tcp open netbios-ssn
>445/tcp open microsoft-ds
>6000/tcp open X11
>
>but did the ports 111, 139, 445 (which i know are vulnerable under
>win... bip )
>must be open?

Only if you want to test your vulnerability to viruses...

What ports need to be open depends on exactly what you're doing/want
to do. Take a look thru /etc/services.

Mike-

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(E-Mail Removed) (kennux) said:
>I just have internet at home and i want to know the minimum numbers of
>ports which must be open to my connection works properly.

Depends on your use. F.ex. I don't have any specific inbound openings,
and my connection works fine.

In _very_ short form:

# set up default policies
iptables -P FORWARD DROP
iptables -P OUTPUT ACCEPT
iptables -P INPUT DROP
# empty&delete all current rules
iptables -F
iptables -X
# define acceptable inbound traffic
iptables -I INPUT -i lo -j ACCEPT
iptables -I INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT

The above will allow all locally-initiated communication, but drop to
floor all connection attempts that come from outside. Start from that,
check groups.google.com for my other postings either in this group or in
comp.os.linux.security to work your way from the above to fill your
specific connectivity needs.

>a nmap localhost gives :

Note, your fw rules may well be set up so that there's no filtering for
traffic arriving from localhost interface - so nmap localhost may give
very different results than scanning from outside.

>but did the ports 111, 139, 445 (which i know are vulnerable under
>win... bip )
>must be open?

No need for your Internet connectivity. Do you want to provide samba
(Windows file-share) services to someone over the Internet?

>I use the following script :
>http://monmotha.mplug.org/firewall/index.php
>for my firewall.

Do you understand it?
If not, then don't use it until you understand. Anyway, it's changing the
security settings of your system - and I consider changing security
settings without understanding the details is a bad habit.
--
Wolf a.k.a. Juha Laiho Espoo, Finland
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