Would be handy if anyone could work out how to allow multiple telnet instances. Could be another handy feature to add to customized firmware builds.
Earlier versions of Zyxel firmwares allowed this, then Zyxel randomly limited it to 1 session. It means if something like DslStats hangs then the modem effectively locks you out of telnet until the session eventually times out.
I'm looking at you Johnson
So I had a play with what could be changed to allow more than one telnet/ssh session. Unfortunately messing with these firmwares is not much fun as all the important features and settings are hidden inside binaries with no source supplied in the GPL package.
Seems the change to telnet sessions was hardcoded in the telnetd binary as the "A telnet session already exist, cannot creat new telnet session" message is contained within it.
As far as I can tell this seems to be the only change to it since the version which allowed multiple sessions (all the way back with AAJZ.3 from 2014) so I just swapped in that version and it seems to work fine. This is probably both
bad and
wrong, but given we are using telnet anyway and it seems they have not upgraded it since release, I guess we are not that concerned about its possible security holes.
No joy trying the same approach with ssh sessions, as far as I can tell ssh doesnt even work for me with the AAJZ.03 release.
So here are 4 more firmwares with the old telnetd binary to allow multiple sessions:
https://www.dropbox.com/sh/q4y2y2kbhb7mb1i/AAA6C520hnZVD0RtStqvRz_da?dl=0As per the last link the -oldtelnet.bin just have the jumbo frames patches and old binary, with -3925.bin the updated adsl_phy.bin.
Hope someone finds them useful, but a warning that I have only tried the 1312-B10A version out, so maybe wait until I have tried the 8324, might do it in a minute actually.