Port Forwarding List disappeared!

brobin

Occasional Visitor
RT-AC1750 B1 running f/w 3.0.0.4.386_49703 with 3 AiMesh nodes. All of a sudden I couldn't connect to my cameras or other devices while I was traveling. When I got home I looked at the Port Forwarding list in the router and it was blank - NADA - no entries. All other settings in the router and the static address list were fine. I restored from a backup and all has been well since but I'd like to understand how this happened and what, if anything, can be done to prevent it from happening again. Ideas?
 

Dr.Mxyztplk

Occasional Visitor
I have a similar issue. When I enter the values it shows them, but if I go to another page & come back they are gone. There's no [SAVE] button or anything & from what I have found online a lot of people have this issue & there are a few solutions, but none of them have worked for me. For me when that happens I clear some space on the NVRAM & it work again until the NVRAM gets full again.

The most common is that the JFFS partition is full. Restoring from a backup could have solved this problem. For me the JFFS Partition only has 3.07/62.75 MB used, so that definitely isn't my problem.

Personally I have chronically low NVRAM (56765/65536 bytes used) currently, after running a script to remove unused entries, & when it gets full my Port Forwarding always disappear, similar to what you are saying. Restoring from a backup could also have fixed this problem.

So for some reason some people have them stored on JFFS (I wish I was one of them) while others, like me, seem to have it stored in NVRAM. Whichever case you are in when the location gets full the router seems to toss them to make room for other things. So far I have found no solution to this problem
 

brobin

Occasional Visitor
Thanks, that gives me a direction to look at. It's only happened once in the 4 years I've had it so if it takes that long to fill up either of those I'll probably have a new router by then.
 

Dr.Mxyztplk

Occasional Visitor
Thanks, that gives me a direction to look at. It's only happened once in the 4 years I've had it so if it takes that long to fill up either of those I'll probably have a new router by then.
For me the DHCP Reservations is a big NVRAM Hog. So are QoS Rules, VPN Settings, things like that. If you've filled it up it's not really a time thing, it's going to get full again.

There are only 64KB of NVRAM on my router & I know a lot have the same. it shows as 63697/65536 bytes. 1 byte is a single letter in ASCII, but if using Unicode each character is 2 bytes. I'll assume everything that it uses will be in ASCII, but I know you can have Unicode characters in a WiFi SSID or Password, & I believe if it uses a single Unicode character for a variable setting the whole thing is Unicode, so standard lowercase & capitals, numbers, spaces, hyphens, underscores, all each take a bit or 2.
It fills up pretty quick, especially since each space, comma, enter return, colon, etc each count for one. 65,000 doesn't seem like a lot anymore.

So lets say you use a DHCP Reservation for Tom's Laptop, That's 12 just for the name, 15 for the IP address, 17 for the MAC, & then at least 3 characters separating each set, another for the return to the next line we're at almost 50 bytes per entry. That's on top of what it uses for the global parameters & to format & control the file itself.

You're thinking 64,000bytes is a lot. But most of that isn't even your settings. I don't know how much exactly & I think it differs between releases & devices, but for me after I take out all the things that I can see in the NVRAM Table I get from nvram show | awk '{print length(), $0 | "sort -n -r"}' | cut -d"=" -f 1 | head -n 20 that leaves 55,874 bytes unaccounted for, those are used by the OS, I know part of that is used by the Default ASUSwrt firmware, but Merlin uses more. But if we assume 56K of your 64K is already taken before you add any config... That's only 8,000 bytes that you have to work with. It goes quick.

Now all of those things are things that if you move to a different router you will probably be using the same.

Unless you are switching to something other than merlin. In which case you're on stock firmware which won't have theses issues or are on a similar Custom Firmware & will likely have the same issues.
 

dosborne

Very Senior Member
Given all the security attacks that typically target devices that use port forwarding such as cameras, NAS (search on "deadbolt ransomware" for example) and many others, you may be wise to look at setting up a VPN service to handle all your remote connections. In the end it is usually much better (simple access to your entire Lan and all devices through one tool) and considerably more secure.

Just a thought for you to consider.
 

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