> On May 12, 2020, at 7:08 AM, Yousong Zhou <yszhou4t...@gmail.com> wrote:
>
> On Sat, 2 May 2020 at 03:21, Philip Prindeville
> <phil...@redfish-solutions.com> wrote:
>>
>> From: Philip Prindeville <phil...@redfish-solutions.com>
>>
>> If the start_time > stop_time on a rule, then the --contiguous arg
>> should be included in the rule.
>
> It seems that start_time >= stop_time has its defined meaning in
> xt_time module. Better add another uci option for this --contiguous
> flag.
>
> Regards,
> yousong
Sorry, not following. What would that UCI option look like?
From iptables-extensions:
time
This matches if the packet arrival time/date is within a given range.
All options are optional, but are ANDed when specified. All times are
interpreted as UTC by default.
--datestart YYYY[-MM[-DD[Thh[:mm[:ss]]]]]
--datestop YYYY[-MM[-DD[Thh[:mm[:ss]]]]]
Only match during the given time, which must be in ISO 8601 "T"
notation. The possible time range is 1970-01-01T00:00:00 to
2038-01-19T04:17:07.
If --datestart or --datestop are not specified, it will default
to 1970-01-01 and 2038-01-19, respectively.
--timestart hh:mm[:ss]
--timestop hh:mm[:ss]
Only match during the given daytime. The possible time range is
00:00:00 to 23:59:59. Leading zeroes are allowed (e.g. "06:03")
and correctly interpreted as base-10.
[!] --monthdays day[,day...]
Only match on the given days of the month. Possible values are 1
to 31. Note that specifying 31 will of course not match on
months which do not have a 31st day; the same goes for 28- or
29-day February.
[!] --weekdays day[,day...]
Only match on the given weekdays. Possible values are Mon, Tue,
Wed, Thu, Fri, Sat, Sun, or values from 1 to 7, respectively.
You may also use two-character variants (Mo, Tu, etc.).
--contiguous
When --timestop is smaller than --timestart value, match this as
a single time period instead distinct intervals. See EXAMPLES.
--kerneltz
Use the kernel timezone instead of UTC to determine whether a
packet meets the time regulations.
About kernel timezones: Linux keeps the system time in UTC, and always
does so. On boot, system time is initialized from a referential time
source. Where this time source has no timezone information, such as the
x86 CMOS RTC, UTC will be assumed. If the time source is however not in
UTC, userspace should provide the correct system time and timezone to
the kernel once it has the information.
Local time is a feature on top of the (timezone independent) system
time. Each process has its own idea of local time, specified via the TZ
environment variable. The kernel also has its own timezone offset vari‐
able. The TZ userspace environment variable specifies how the UTC-based
system time is displayed, e.g. when you run date(1), or what you see on
your desktop clock. The TZ string may resolve to different offsets at
different dates, which is what enables the automatic time-jumping in
userspace. when DST changes. The kernel's timezone offset variable is
used when it has to convert between non-UTC sources, such as FAT
filesystems, to UTC (since the latter is what the rest of the system
uses).
The caveat with the kernel timezone is that Linux distributions may
ignore to set the kernel timezone, and instead only set the system
time. Even if a particular distribution does set the timezone at boot,
it is usually does not keep the kernel timezone offset - which is what
changes on DST - up to date. ntpd will not touch the kernel timezone,
so running it will not resolve the issue. As such, one may encounter a
timezone that is always +0000, or one that is wrong half of the time of
the year. As such, using --kerneltz is highly discouraged.
EXAMPLES. To match on weekends, use:
-m time --weekdays Sa,Su
Or, to match (once) on a national holiday block:
-m time --datestart 2007-12-24 --datestop 2007-12-27
Since the stop time is actually inclusive, you would need the following
stop time to not match the first second of the new day:
-m time --datestart 2007-01-01T17:00 --datestop
2007-01-01T23:59:59
During lunch hour:
-m time --timestart 12:30 --timestop 13:30
The fourth Friday in the month:
-m time --weekdays Fr --monthdays 22,23,24,25,26,27,28
(Note that this exploits a certain mathematical property. It is not
possible to say "fourth Thursday OR fourth Friday" in one rule. It is
possible with multiple rules, though.)
Matching across days might not do what is expected. For instance,
-m time --weekdays Mo --timestart 23:00 --timestop 01:00 Will
match Monday, for one hour from midnight to 1 a.m., and then
again for another hour from 23:00 onwards. If this is unwanted,
e.g. if you would like 'match for two hours from Montay 23:00
onwards' you need to also specify the --contiguous option in the
example above.
This last section is the bit that I’m trying to address.
I’m in GMT-0700.
So if I want a rule granting access from 8am to 9pm… local, that’s 14:00 GMT …
03:00 GMT, but it requires the --contiguous flag for the above reason.
Are you suggesting adding an option like:
option contiguous true | false
that would cause the argument to get appended when timestart > timestop?
Would it always be appended or just when timestart > timestop (it’s not clear
what it does in the case where timestart < timestop && contiguous)?
>
>>
>> Signed-off-by: Philip Prindeville <phil...@redfish-solutions.com>
>> ---
>> iptables.c | 3 +++
>> 1 file changed, 3 insertions(+)
>>
>> diff --git a/iptables.c b/iptables.c
>> index
>> 559fe7defef3be85c4eb2934884caf549f932bc5..5c02e6e26c93468f4ef6a7f917069bb49985aad8
>> 100644
>> --- a/iptables.c
>> +++ b/iptables.c
>> @@ -1099,6 +1099,9 @@ fw3_ipt_rule_time(struct fw3_ipt_rule *r, struct
>> fw3_time *time)
>> fw3_ipt_rule_addarg(r, false, "--timestop", buf);
>> }
>>
>> + if (time->timestart && time->timestop && time->timestart >
>> time->timestop)
>> + fw3_ipt_rule_addarg(r, false, "--contiguous", NULL);
>> +
>> if (time->monthdays & 0xFFFFFFFE)
>> {
>> for (i = 1, p = buf; i < 32; i++)
>> --
>> 2.17.2
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