completely disable telenet access to a mullti layer switch

PashPash Member Posts: 1,600 ■■■■■□□□□□
We have a 6500 switch running CatOS at L2 and IOS at L3. The L3 part is easy with use of access list's, but the L2 part seems to be a stopgap. I was under the impression:

"set ip permit enable telnet" command without supplying a permit list would disable telnet access entirely, but our clients pen testers seem to believe differently.

Does anyone have any ideas how I can remove telenet access entirely from this 6500 switch?

Cheers,

Pash
DevOps Engineer and Security Champion. https://blog.pash.by - I am trying to find my writing style, so please bear with me.

Comments

  • jason_lundejason_lunde Member Posts: 567
    I am not a big CatOS guru, but I believe the command to disable it is:

    set ip permit X.X.X.X Y.Y.Y.Y telnet
    set ip permit disable telnet

    try that out, and let me know...
  • rwwest7rwwest7 Member Posts: 300
    Couldn't you also add:

    conf t
    line vty 0 X
    no password
    login


    Then if somebody is able to get through the access list, they would get the "password required but none set" error.
  • LBC90805LBC90805 Member Posts: 247
    rwwest7 wrote: »
    Couldn't you also add:

    conf t
    line vty 0 X
    no password
    login


    Then if somebody is able to get through the access list, they would get the "password required but none set" error.

    Those commands would just allow someone to log into the VTY without a password. Correct me if I'm wrong, someone, but that wouldn't turn off TELNET altogether.

    I was thinking something along the lines of "No Transport Input SOMETHING".
  • networker050184networker050184 Mod Posts: 11,962 Mod
    LBC90805 wrote: »
    Those commands would just allow someone to log into the VTY without a password. Correct me if I'm wrong, someone, but that wouldn't turn off TELNET altogether.

    You're thinking of no login.
    An expert is a man who has made all the mistakes which can be made.
  • amp2030amp2030 Member Posts: 253
    LBC90805 wrote: »
    I was thinking something along the lines of "No Transport Input SOMETHING".

    "Transport Input SSH" should do the trick...
  • tierstentiersten Member Posts: 4,505
    I am not a big CatOS guru, but I believe the command to disable it is:

    set ip permit X.X.X.X Y.Y.Y.Y telnet
    set ip permit disable telnet

    try that out, and let me know...
    This should do it.
  • tierstentiersten Member Posts: 4,505
    LBC90805 wrote: »
    Those commands would just allow someone to log into the VTY without a password. Correct me if I'm wrong, someone, but that wouldn't turn off TELNET altogether.

    I was thinking something along the lines of "No Transport Input SOMETHING".
    It is running CatOS and not IOS...
  • PashPash Member Posts: 1,600 ■■■■■□□□□□
    Thanks for response guys:

    set ip permit X.X.X.X Y.Y.Y.Y telnet
    set ip permit disable telnet

    We will try thaat jason thanks.

    Its actually a multi layer switch, so L2 catOS L3 IOS
    DevOps Engineer and Security Champion. https://blog.pash.by - I am trying to find my writing style, so please bear with me.
  • rwwest7rwwest7 Member Posts: 300
    LBC90805 wrote: »
    Those commands would just allow someone to log into the VTY without a password. Correct me if I'm wrong, someone, but that wouldn't turn off TELNET altogether.

    I was thinking something along the lines of "No Transport Input SOMETHING".
    No, those commands would basically disable Telnet. If you require a login but have no password set, then Cisco is smart enough to not allow telnet until a password is set.
  • LBC90805LBC90805 Member Posts: 247
    You're thinking of no login.

    I knew I was missing something. It's been awhile since I goofed around with the "line" commands.
Sign In or Register to comment.