Iptables: port 22 open only for my IP

Stuart Sears stuart at sjsears.com
Tue Jun 29 14:02:23 UTC 2004


Khan wrote:

> Hello,
>
> I am total beginner to Linux and I'm trying to learn iptables basics. 
> I would like to learn how to close all ports but 80, 20, and that 
> ports 22 and 10000 will be open only to my IP address.
>
> How can I do that.
>
> TNX!

first, a hint or two:
RTFM (man iptables, quite helpful actually, will explain what some of 
this actually does!)
http://www.netfilter.org has some very good simple guides to how this works.
http://www.tldp.org has some good howtos

now some ideas.

# set default policy on INPUT chain
# ie, what to do with packets that don't match my rules
iptables -P INPUT DROP
# accept tcp packets for port 80
iptables -t filter -A INPUT -p tcp --dport 80 -j ACCEPT
# accept tcp and udp packets for port 20
iptables -t filter -A INPUT -p tcp --dport 20 -j ACCEPT
iptables -t filter -A INPUT -p udp --dport 20 -j ACCEPT

#accept packets from your ip address for port 22 (ssh is tcp so i have 
used that)
iptables -t filter -A INPUT -m tcp -p tcp --dport 22 -s 
your.ip.addr.here -j ACCEPT
# incidentally, it will also accept --dport ssh if you like

# accept inbound packets for port 10000 from your ip
iptables -t filter -A INPUT  -p tcp --dport 10000 -s your.ip,addr,here 
-j ACCEPT
iptables -t filter -A INPUT -p udp --dport 10000 -s your.ip,addr,here -j 
ACCEPT






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