Hi,
I'm not sure where to ask this question, you, redhat or netfilter so I'll ask you guys first, hoping you can redirect me where this post belongs. I have an issue with my CentOS 6 box with named chains in iptables. Apparently there is a builtin #define to limit chain names up to 30 chars, but the test condition fails and iptables crashes with a stacktrace.
# cat /etc/redhat-release CentOS Linux release 6.0 (Final)
# rpm -qa | fgrep iptables iptables-ipv6-1.4.7-3.el6.x86_64 iptables-1.4.7-3.el6.x86_64
Use cases prove that you can create chains with names up to =30 chars but you can only reference <=28 chars named chains. Trying to reference a 29 or 30 chars named chains will crash iptables.
=====
Use cases with 28,29,30 and 31 chars long named chains:
# iptables -N $(for((i=0;i<28;i++));do printf "%s" "a";done) && echo ok || echo ko ok
# iptables -N $(for((i=0;i<29;i++));do printf "%s" "b";done) && echo ok || echo ko ok
# iptables -N $(for((i=0;i<30;i++));do printf "%s" "c";done) && echo ok || echo ko ok
iptables -N $(for((i=0;i<31;i++));do printf "%s" "d";done) && echo ok || echo ko iptables v1.4.7: chain name `ddddddddddddddddddddddddddddddd' too long (must be under 30 chars) Try `iptables -h' or 'iptables --help' for more information. ko
# iptables -I INPUT -j aaaaaaaaaaaaaaaaaaaaaaaaaaaa && echo ok || echo ko ok
# iptables -I INPUT -j bbbbbbbbbbbbbbbbbbbbbbbbbbbbb && echo ok || echo ko <stacktrace> ko
# iptables -I INPUT -j cccccccccccccccccccccccccccccc && echo ok || echo ko <stacktrace> ko
I can attach strace output or the stacktrace if required. Any infos where to report this issue much appreciated.
Florian.
Florian CROUZAT wrote on 2011-09-28:
Hi,
I'm not sure where to ask this question, you, redhat or netfilter so I'll ask you guys first, hoping you can redirect me where this post belongs. I have an issue with my CentOS 6 box with named chains in iptables. Apparently there is a builtin #define to limit chain names up to 30 chars, but the test condition fails and iptables crashes with a stacktrace.
# cat /etc/redhat-release CentOS Linux release 6.0 (Final)
# rpm -qa | fgrep iptables iptables-ipv6-1.4.7-3.el6.x86_64 iptables-1.4.7-3.el6.x86_64
Use cases prove that you can create chains with names up to =30 chars but you can only reference <=28 chars named chains. Trying to reference a 29 or 30 chars named chains will crash iptables.
=====
Use cases with 28,29,30 and 31 chars long named chains:
# iptables -N $(for((i=0;i<28;i++));do printf "%s" "a";done) && echo ok || echo ko ok
# iptables -N $(for((i=0;i<29;i++));do printf "%s" "b";done) && echo ok || echo ko ok
# iptables -N $(for((i=0;i<30;i++));do printf "%s" "c";done) && echo ok || echo ko ok
iptables -N $(for((i=0;i<31;i++));do printf "%s" "d";done) && echo ok || echo ko iptables v1.4.7: chain name `ddddddddddddddddddddddddddddddd' too long (must be under 30 chars) Try `iptables -h' or 'iptables --help' for more information. ko
# iptables -I INPUT -j aaaaaaaaaaaaaaaaaaaaaaaaaaaa && echo ok || echo ko ok
# iptables -I INPUT -j bbbbbbbbbbbbbbbbbbbbbbbbbbbbb && echo ok || echo ko <stacktrace> ko
# iptables -I INPUT -j cccccccccccccccccccccccccccccc && echo ok || echo ko
<stacktrace> ko
I can attach strace output or the stacktrace if required. Any infos where to report this issue much appreciated.
This bug is not reproducible on CentOS release 5.6 (Final).
Florian
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Florian CROUZAT