I have Comcast business internet with a static IP and Comcast's model SMCD3G router. I was shocked to discover that I could connect to the configuration page and login with the default username/password from a remote site. I couldn't see a way to disable this feature, so I decided to change the password to something really long and difficult to brute force. I did a cut and paste, so I know and have record of what I changed it to, but now I can't login even from inside my LAN. It just gives "incorrect login".
But it may be paritally my fault.
For the first password I entered (e.g.):
"There are more things in heaven and earth, Horatio"
This was so long, I had no idea if it took all the characters or it was truncated. So, for the second password I entered something shorter, and something that did not match the first (e.g.):
"There are more things in heaven"
I hit enter expecting it to say they did not match, but it accepted them as the same, so some truncating is going on, but I can't seem to login. I've tried leading substrings from 8 to full length, but nothing works. I did try the original password and it does not work either.
I'm guessing that the password change form truncated these somehow, or that maybe the password change page truncates them longer than the login page, that is, you are allowed to change to a password longer than you are allowed to login with.
So I have some questions. (1) Does anybody know anything about string truncation, max password length, etc. for this device, and (2) how do I reset the box back to the default password, and I guess (3), how can I turn off the ability to login to the router from the Internet side?
Passwords are case-sensitive and can contain up to 32 alphanumeric characters. Spaces count as password characters.
Restoring Factory Defaults
Using the Reset button on the back panel, you can power cycle the Gateway and return it to its original factory default settings. As a result, any changes you made to the Gateway’s default settings will be removed.
1. Leave power plugged into the Gateway. 2. Find the Reset button on the back panel, then press and hold it for at least 10 seconds. 3. Release the Reset button.
Turning off the ability to log in to the router from the Internet is covered under "Configuring Access Control" / "Remote IPs" on pp. 39-40 (I think). Actually, I don't see anything that says that router configuration can be accessed from the internet.
(1) Does anybody know anything about string truncation, max password length, etc. for this device?
(2) how do I reset the box back to the default passwor?
(3), how can I turn off the ability to login to the router from the Internet side?
(1) As already noted, the max is 32 alphanumeric chars. This seems to include space, but no other chars are mentioened, so I would stay away from anything other than letters, numbers, and space.
(2) Press and hold hte recessed Reset button on the back of the device for 10 seconds to reset all settings to factory defaults, so the userid is "cusadmin" and the password is "password".
(3) There does not appear to be a setting to control this on this device, at least not according to the manual. There are many normal router/gateway features missing from this device, unfortunately. Comb through the admin interface on your device, there might be options not described in the manual. Otherwise, call Comcast or SMC for more in depth help.
I see your post is a little old but I'm in the same boat except that the password I used was way under 32 characters.
I had not tested access from outside but I'm a little disappointed to see that it could be logged into with that default information from the outside interface. Even Verizon DSL Westell devices have that blocked. You have to login from inside first and enable remote login.
Anyway, any luck or did you resort to resetting to factory defaults?