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User-Agent: Mozilla/4.76 [en] (X11; U; Linux 2.4.1 i686)
The "ipchains-restore" script automatically creates chains mentioned as
rule targets. Built-in targets, however, are not created as chains. These
include REJECT, DENY, ACCEPT, REDIRECT, and MASQ.
That list *should* also include RETURN, but it does not. If a rule uses
the built-in RETURN target, ipchains-restore will instead create an empty
Once that happens, will matched packets use the built-in RETURN target or
will they go to this bogus RETURN chain? I'm not sure. If the later, then
this bug has the potential to seriously compromise sites' packet filtering
Steps to Reproduce:
As root, run the following commands:
# ipchains -A input -j RETURN
# service ipchains save
# service ipchains restore
Actual Results: Diagnostic output: "Auto-creating chain RETURN".
Running "ipchains -L" confirms the incorrect creation of a RETURN chain.
Expected Results: No diagnostic output, and no creation of a RETURN
chain. Rules with target RETURN use the built-in RETURN target, not a
chain named RETURN.
The following patch fixes the problem in the obvious manner:
--- ipchains-restore-bad Thu Feb 1 19:03:18 2001
+++ ipchains-restore Thu Feb 1 19:03:32 2001
@@ -53,6 +53,7 @@
+ RETURN) ;;
*) $IPCHAINS -N $arg 2>/dev/null >/dev/null && if [ $VERBOSE ]; then
echo Auto-creating chain $arg; fi
Created attachment 8699 [details]
suggested fix; same as in original report, but without screwey line wrapping