How iptables behaves on timezone change?

Question

I have doubt how iptables keep changing the info in iptables when timezone is change. I am using iptables s v 1.4.8

I have blocked one IP with following details

 # date
    Thu Jun 6 12:46:42 IST 2013

#iptables -A INPUT -s 10.0.3.128 -m time --datestart 2013-6-6T12:0:00 --datestop 2013-6-6T13:0:00 -j DROP

# iptables -L
Chain INPUT (policy ACCEPT)
target prot opt source destination
DROP all -- 10.0.3.128 anywhere TIME starting from 2013-06-06 12:00:00 until date 2013-06-06 13:00:00

Chain FORWARD (policy ACCEPT)
target prot opt source destination

Chain OUTPUT (policy ACCEPT)
target prot opt source destination

But after I change the timezone following things happened automatically .

AFTER TIME ZONE CHANGE +++++++++++++++++++++++

#date
Thu Jun 6 15:17:48 HKT 2013

# iptables -L
Chain INPUT (policy ACCEPT)
target prot opt source destination
DROP all -- 10.0.3.128 anywhere TIME starting from 2013-06-06 14:30:00 until date 2013-06-06 15:30:00

Chain FORWARD (policy ACCEPT)
target prot opt source destination

Chain OUTPUT (policy ACCEPT)
target prot opt source destination
#

The time value is changed in the rule . It is changing with the timezone how. Where iptables keeps track of timezone.

Kindly explain me.

Answer 1

It's not keeping track of anything. It converted the strings 2013-6-6T12:0:00 and 2013-6-6T13:0:00 to raw time_t when you added the rule, using the timezone that you had set up at that time. Then later when you run the -L, it converts that timestamp back to a readable string using the new current timezone.

The timezone information that was implicit in your initial command was lost immediately after it was done executing, and every execution of iptables -L attempts to reconstruct the original time string by applying the current timezone to the time_t.