I'd like to create a single rule in iptables (if possible) that uses multiple source IP addresses. Is this possible?
This is only possible if you can aggregate the source IP's you want into a contiguous range. eg
iptables -A INPUT -s 192.168.0.0/24 -d 192.168.0.5 -p tcp -j ACCEPT
If you cannot find a common netmask that covers the IP's you want, you'll have to write several identical rules to do what you want.
There are several iptables frameworks around which can deal with the low level of writing the iptables rules, allowing you to define your rules at a more symolic level. Shorewall is a common one that ships with most current linux distributions.
you can use the iprange module in combination with '--src-range' like for e.x.:
-A INPUT -i eth0 -m iprange --src-range 192.168.1.90-192.168.1.101 -j ACCEPT
Source: iptables 1.4.7 man page
iprange This matches on a given arbitrary range of IP addresses. [!] --src-range from[-to] Match source IP in the specified range. [!] --dst-range from[-to] Match destination IP in the specified range.
(i know this is like a 4 year old question, but just to answer for anyone who seeks this on the net)
The original question is from May 2009, but since May 2011 the Linux kernel has had a feature to address this need called ipset.
Here is an example creating an ipset, adding addresses to it, and then using it in a firewall rule:
ipset -N office365 iphash ipset -A office365 220.127.116.11 ipset -A office365 18.104.22.168 ipset -A office365 22.214.171.124 ipset -A office365 126.96.36.199 ipset -A office365 188.8.131.52 ipset -A office365 184.108.40.206 ipset -A office365 220.127.116.11 ipset -A office365 18.104.22.168 ipset -A office365 22.214.171.124 ipset -A office365 126.96.36.199 iptables -A OUTPUT -m set --match-set office365 dst -j ACCEPT
man iptables and
man ipset for more info.
In addition to the comment of Bòss King, you can also simply specify several addresses seperated with a comma:
[!] -s, --source address[/mask][,...] Source specification. Address can be either a network name, a hostname, a network IP address (with /mask), or a plain IP address. Hostnames will be resolved once only, before the rule is submitted to the kernel. Please note that specifying any name to be resolved with a remote query such as DNS is a really bad idea. The mask can be either a network mask or a plain number, specifying the number of 1's at the left side of the network mask. Thus, a mask of 24 is equivalent to 255.255.255.0. A "!" argument before the address specification inverts the sense of the address. The flag --src is an alias for this option. Multiple addresses can be specified, but this will expand to multiple rules (when adding with -A), or will cause multiple rules to be deleted (with -D).
You can define multiple chains such that you can combine independent lists of requirements. I doubt this is exactly what you want, but it's still pretty handy. We use this to define lists of valid user-types by IP, and then apply port restrictions to the source networks. So, for instance:
# Allow SMTP from anywhere -A tcp_inbound -p tcp -m tcp -s 0/0 --dport 25 -j allowed # # Define the set of IP ranges we'll send to the tcp_user_inbound chain -A tcp_inbound -p tcp -m tcp -s 172.19.1.0/24 -j tcp_user_inbound -A tcp_inbound -p tcp -m tcp -s 172.19.6.0/23 -j tcp_user_inbound -A tcp_inbound -p tcp -m tcp -s 172.19.8.0/24 -j tcp_user_inbound -A tcp_inbound -p tcp -m tcp -s 172.19.10.0/23 -j tcp_user_inbound -A tcp_inbound -p tcp -m tcp -s 172.19.12.0/23 -j tcp_user_inbound -A tcp_inbound -p tcp -m tcp -s 172.19.4.0/23 -j tcp_user_inbound # # Ports we allow access to based on a source-address prereq. # SSH -A tcp_user_inbound -p tcp -m tcp --dport 22 -j allowed # VNC -A tcp_user_inbound -p tcp -m tcp --dport 5950:5958 -j allowed # https -A tcp_user_inbound -p tcp -m tcp --dport 443 -j allowed
Let's say for example that you only want to accept SMTP packets that come from 10.0.0.2 or 192.168.1.2. You can user the following rules:
# create a new chain iptables --new-chain multiple_sources_smtp # send all SMTP connections to the new chain iptables --append INPUT --protocol tcp --dport 25 --jump multiple_sources_smtp # use the default INPUT rules for packets coming from allowed sources iptables --append multiple_sources_smtp --source 10.0.0.2 --jump RETURN iptables --append multiple_sources_smtp --source 192.168.1.2 --jump RETURN # drop packets from anywhere else iptables --append multiple_sources_smtp -j DROP
Or as the output of
# Generated by iptables-save v1.4.14 on Sat Dec 6 09:17:11 2014 *filter :INPUT ACCEPT [32:13325] :FORWARD ACCEPT [0:0] :OUTPUT ACCEPT [25:3084] :multiple_sources_smtp - [0:0] -A INPUT -p tcp -m tcp --dport 25 -j multiple_sources_smtp -A multiple_sources_smtp -s 10.0.0.2/32 -j RETURN -A multiple_sources_smtp -s 192.168.1.2/32 -j RETURN -A multiple_sources_smtp -j DROP COMMIT # Completed on Sat Dec 6 09:17:11 2014