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TTL with external router?

Posted: Mon Nov 30, 2020 8:30 am
by lawnmowerman
I have a MOFI in bridge mode, so acting just as a modem, connected to an external ASUS router. I want to confirm my TTL setting on the MOFI is set right to make sure Verizon sees internet traffic as coming from a phone and not a router/hotspot device.

Setting the TTL on MOFI to 64 or 117 gets fast speeds, while 65 is throttled. So based on this, I have the TTL on the MOFI set to 64. When my computer and/or phone is on the ASUS WIFI and I ping a site from either (say from the Windows command line), it shows TTL=63. I assume it's one less than 64 b/c of the router hop. Is that normal and expected? Or will that be a red flag for Verizon?

The speed is fine, so maybe that answers the question... I just want to make sure there's nothing about it that would indicate to Verizon I'm using a phone plan sim in a non-phone device.

Re: TTL with external router?

Posted: Mon Nov 30, 2020 5:28 pm
by Viper67857
That is normal... The value you see on a ping test is actually the remaining ttl on the return packet. If you didn't have custom firewall rules overwriting the ttl then it would vary a lot depending on the sites you're pinging and how many hops it takes along the way. Since the mofi is setting it to 64 on both incoming and outgoing packets, you'll always see 63 as your other router is decrementing it by 1.

Re: TTL with external router?

Posted: Mon Nov 30, 2020 5:44 pm
by lawnmowerman
Cool, thanks! Just wanted to make sure there was nothing there that would look suspect to VZ.