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Operating Systems BSD Deny logon for x hours if login failed x times Post 302253557 by brightstorm on Friday 31st of October 2008 10:39:24 PM
Old 10-31-2008
Deny logon for x hours if login failed x times

Hello,

I have a small inquiry.
Sometimes, my good friend, Charlie Root, sends me security notifications that a possible breakin attempt has occured. It looks like this:

Oct 29 06:58:17 cigva sshd[<random port>]: reverse mapping checking getaddrinfo for 180.144.164.220.broad.sm.yn.dynamic.163data.com.cn [220.164.144.180] failed - POSSIBLE BREAK-IN ATTEMPT!

(goonet.info is probably the worst culprit yet on my system with downright spamming).

As far as I can see, that connection is not one I'd want to allow. I do not recognize any of the IP adresses above. My system rejects it but I would like to add a bit extra to help get rid of these would-be hackers.

Does any of you know what people are actually trying to do? Are they scanning for SSH connections to abuse or...?

Is it possible to either:

1. Prevent this from being able to be done every second (i.e. increase it to a 10 seconds delay between the attempts on <whatever he is doing>?

2. Can you deny logon for specified time from a given IP if several login attempts from that IP is made (ex. >= 3 failed)?

Thanks,
Klaus Smilie

Last edited by brightstorm; 10-31-2008 at 11:44 PM..
 

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ttys(4) 						     Kernel Interfaces Manual							   ttys(4)

NAME
ttys - Terminal control database file (Enhanced Security) DESCRIPTION
Notes The secure terminal database file, /etc/securettys, controls root logins for all security levels. The file is described in the securet- tys(4) reference page. By default, the enhanced security terminal control information is stored in database format (ttys.db). The information was formerly stored in the ttys file and is converted to database format in an update installation. The convauth utility converts an existing ttys file to database format. The enhanced security terminal control database (ttys.db) contains an entry for each terminal or X displayname that can be used for logging in. It supports wildcarding of the entire terminal name or displayname only. Authentication programs use information in the terminal con- trol database to determine if a login is permitted on the specified terminal. Information from the device assignment database (/etc/auth/system/devassign) can also affect terminal login permissions. Successful and unsuccessful login attempts on the terminal are optionally recorded in the terminal control database, and the information can be used to disable terminal logins when breakin attempts are suspected. The /usr/tcb/bin/dxdevices GUI provides a way to create terminal control database entries and to alter the system default values for the fields. The edauth utility can also be used to display and modify terminal control database entries. A terminal control database entry consists of keyword field identifiers and values for those fields. If a necessary value is not specified in an entry, a default value for the field is supplied from the system default file (/etc/auth/system/default). For more information on the field format, see the authcap(4) reference page. The following keyword field identifiers are supported: This field defines the terminal device name for the entry. The system expects that terminal devices are in the /dev directory and therefore this prefix should not be specified. If the terminal entry describes the /dev/tty1 device, the t_devname field should contain tty1. This field is ignored if it is set in a template or in the default database. This field contains the user ID of the last user who successfully logged in using the terminal device. This field is ignored if it is set in a tem- plate or in the default database. This field is a time_t value that records the last successful login time to the terminal device. This field is ignored if it is set in a template or in the default database. This field contains the user ID of the last user who unsuccess- fully attempted to log in using the terminal device. This field is ignored if it is set in a template or in the default database. This field is a time_t value that records the last unsuccessful login time to the terminal device. This field is ignored if it is set in a tem- plate or in the default database. This field contains the user ID of the user who successfully logged in before the user identified in the t_uid field. This represents the UID of the previous login session. This field is ignored if it is set in a template or in the default database. This field is a time_t value that contains the system time of last logout associated with this terminal device. This value marks the end of the previous login session associated with the user identified by t_prevuid. This field records the number of consecutive unsuccessful login attempts to the terminal device. This field is ignored if it is set in a template or in the default database. This field specifies the maximum number of consecutive unsuccessful login attempts permitted using the terminal before the terminal is locked. Once the terminal is locked, it must be unlocked by an authorized administrator. This field is a time_t value that identifies the login delay enforced by authentication programs between unsuccessful login attempts. This field is designed to slow the rate at which penetration attempts on a terminal device can occur. This field indicates whether the terminal device has been administratively locked. This field is manipulated by authorized administrators only. This field specifies the time interval in seconds after t_unsuctime to wait before ignoring t_failures. Zero means never ignore t_failures. This field specifies the login time-out value in seconds. If a login attempt is initiated by entering a user name at the login prompt but successful authentication is not completed within the time-out interval specified, the login attempt is aborted. This field indicates that the entry is an X window display managed by rather than a terminal device. This field is ignored if it is set in a template or in the default database. EXAMPLES
The following example shows a typical terminal control database entry: console:t_devname=console: :t_uid=jdoe:t_logtime#675430072: :t_unsucuid=jdoe:t_unsuctime#673610809: :t_prevuid=root:t_prevtime#671376915: :chkent: This entry is for the system console device, /dev/console. The most recent successful login session was for the user jdoe. The most recent unsuccessful login attempt was also by user jdoe. Before the most recent successful login session, the root account was used to log in to the console. The entry records the system time for the current successful login, the end of the previous successful login session, and the time of the most recent unsuccessful login attempt. FILES
Specifies the pathname of the database. RELATED INFORMATION
Commands: login(1) Functions: getprtcent(3) Files: authcap(4), default(4), securettys(4) delim off ttys(4)
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