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iptables on redhat 7.1

Posted on 2001-06-05
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Last Modified: 2010-04-20
i'm using redhat 7.1, and i have problem with iptables
everytime i want to use iptables, it always display this error message

/lib/modules/2.4.2-2/kernel/net/ipv4/netfilter/ip_tables.o: init_module: Device or resource busy
Hint: insmod errors can be caused by incorrect module parameters, including invalid IO or IRQ parameters/lib

/lib/modules/2.4.2-2/kernel/net/ipv4/netfilter/ip_tables.o: insmod /lib......../ip_tables.o failed

iptables 1.2.1a: can't initialize iptables table 'filter': iptables who? (do you need to insmod?) Perhaps iptables or your kernel needs to be upgraded

????
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Question by:ichen
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jlevie earned 100 total points
ID: 6159371
That sounds like ipchains is loaded, which is the default configuration for RH 7.1. To fix, disable ipchains ("chkconfig --level 2345 ipchains off" or via linuxconf) and reboot. Note that iptables won't actually start at boot time until you create a config file (/etc/sysconfig/iptables), but after the reboot you should be able to do "iptables -L".
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by:ichen
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what do you mean by config file?
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by:jlevie
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Well, iptables, like ipcahins, requires a configuation file to tell it what to do. When either are running they default to a filter set that passes everything, something like:

disorder> dwim iptables --list
Chain INPUT (policy ACCEPT)
target     prot opt source               destination        

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination        

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination        

You can see that no filtering is occuring because no rules have been specified manually or via a config file. You probably want to look at the HowTo's (http://netfilter.samba.org/unreliable-guides/) for an explanation of what you can do with iptables/NetFilter (i.e., what goes into the config file). And there are various "canned" config files on the Internet, http://mirkk.kurd.nu/~monmotha/firewall/index.php is one example.
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