Netgate SG-1000 microFirewall

Author Topic: Change default TTL value  (Read 123 times)

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Offline bkcberry

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Change default TTL value
« on: December 05, 2017, 12:03:25 pm »
Hey guys, quick question. I can run the command
Code: [Select]
sysctl net.inet.ip.ttl=128 and get the TTL to change, but if i add

Code: [Select]
net.inet.ip.ttl=128
to /etc/sysctl.conf and reboot, nothing happens. Anyone know how to make this stick?

Offline johnpoz

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Re: Change default TTL value
« Reply #1 on: December 05, 2017, 12:08:58 pm »
you would create it in the gui section for that.

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Offline bkcberry

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Re: Change default TTL value
« Reply #2 on: December 05, 2017, 12:17:42 pm »
Awesome, thanks!!

Offline johnpoz

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Re: Change default TTL value
« Reply #3 on: December 05, 2017, 12:35:42 pm »
If you don't mind why are you needing to change the ttl - that damn curiosity kat of mine is a PITA ;)
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Offline JKnott

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Re: Change default TTL value
« Reply #4 on: December 05, 2017, 01:05:44 pm »
Quote
If you don't mind why are you needing to change the ttl - that damn curiosity kat of mine is a PITA ;)

I was wondering the same thing.

Offline johnpoz

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Re: Change default TTL value
« Reply #5 on: December 05, 2017, 01:13:46 pm »
I saw an issue long time ago 2012 where the dhcp client was setting low ttl of 16 and someone in the EU was unable to get dhcp from their isp.. because it was so many hops away.  Had to recompile the dhcp client for them - even filed a bug with freebsd, which they finally fixed in 2014, like 1 month shy of 2 years later ;)

But other than something like that not sure why would need to change the ttl..

Here is the bug I filed - its the only freebsd bug I ever filed ;)
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=170279

But something like that is really only reason why I would think you would have to set that.. So yeah that damn kat keeps meowing at me on what the problem is ;)
- An intelligent man is sometimes forced to be drunk to spend time with his fools.
- Please don't PM me for personal help
- if you want to say thanks applaud or https://www.freebsdfoundation.org/donate/
1x SG-2440 2.3.4_p1 (work)
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Offline JKnott

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Re: Change default TTL value
« Reply #6 on: December 05, 2017, 01:43:01 pm »
^^^^
A quick peek with Wireshark shows TTL/Hop Limit of 64 outgoing and various values in the 50s incoming.

Offline johnpoz

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Re: Change default TTL value
« Reply #7 on: December 05, 2017, 02:04:32 pm »
Yeah 64 is common default.. 128 is a lot of freaking hops ;)  Which is why so curious to why would need to change to 128..
- An intelligent man is sometimes forced to be drunk to spend time with his fools.
- Please don't PM me for personal help
- if you want to say thanks applaud or https://www.freebsdfoundation.org/donate/
1x SG-2440 2.3.4_p1 (work)
1x SG-4860 2.4.2-RELEASE-p1 (home)

Offline JKnott

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Re: Change default TTL value
« Reply #8 on: December 05, 2017, 02:08:26 pm »
Yeah 64 is common default.. 128 is a lot of freaking hops ;)  Which is why so curious to why would need to change to 128..

Maybe he has a really BIG network.   ;)