How to block local users ports and ips

How to block local users ports and ips - Printable Version

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How to block local users ports and ips - KobrAs - 2004-12-29

Want to block a local user to access a specific port or a specific ip ?

linux-noob.com will help you how to do that :

[root@test tmp]# id test

uid=503(test) gid=503(test) groups=503(test)

[root@test tmp]#

(look at uid= and gid=)

How to block a local user to access any outside ports ?

Code:
iptables -t filter -A OUTPUT -p tcp --dport 6667 --match owner --uid-owner 503 -j DROP

(you may need to change tcp to udp or icmp and --uid-owner to other uid)

How to block a local group to access any outside ports ?

(lets find group 'users' gid by doing grep -i users /etc/group)

Code:
iptables -t filter -A OUTPUT -p tcp --match owner --gid-owner 100 -j DROP

For blocking just specific ports just add --dport port or --sport port after -p protocol

Code:
iptables -t filter -A OUTPUT -p tcp --dport 6667 --match owner --uid-owner 503 -j DROP

Code:
iptables -t filter -A OUTPUT -p tcp --dport 6667 --match owner --gid-owner 100 -j DROP

How to block a specific range of ports ?

Code:
iptables -t filter -A OUTPUT -p tcp --dport 1:1024 --match owner --uid-owner 503 -j DROP

(you may need to change the range 1:1024 (all ports from 1 to 1024) and the uid)

How to block a specific ip destination or source or a specific class (a 256 ips class) on all protocols and ports or to specific port(s)?

destination :

Code:
iptables -t filter -A OUTPUT -d 199.9.9.9 --match owner --uid-owner 503 -j DROP

source :

Code:
iptables -t filter -A OUTPUT -s 199.9.9.9 --match owner --uid-owner 503 -j DROP

full class :

Code:
iptables -t filter -A OUTPUT -d 199.9.9.0/24 --match owner --uid-owner 503 -j DROP

Code:
iptables -t filter -A OUTPUT -s 199.9.9.0/24 --match owner --uid-owner 503 -j DROP

specific destination or source specific ports or range :

Code:
iptables -t filter -A OUTPUT -d 199.9.9.0/24 --dport 6667 --match owner --uid-owner 503 -j DROP

Code:
iptables -t filter -A OUTPUT -d 199.9.9.0/24 --dport 1:1024 --match owner --uid-owner 503 -j DROP

(you many need to change tcp to udp or icmp and --gid-owner to other gid)

(the ips and ports used here are just examples)

Thats all for today.

Greets goes out to ... linux-noob.com

How to block local users ports and ips - anyweb - 2004-12-29

thanks Kobras great post !

pinned !

cheers

anyweb

How to block local users ports and ips - znx - 2005-07-07

nice, proves the power of iptables