Security-Enhanced Linux secures the telnetd processes via flexible mandatory access control.
If you want to allow users to resolve user passwd entries directly from ldap rather then using a sssd serve for the telnetd_t, you must turn on the authlogin_nsswitch_use_ldap boolean.
setsebool -P authlogin_nsswitch_use_ldap 1
If you want to allow confined applications to run with kerberos for the telnetd_t, you must turn on the kerberos_enabled boolean.
setsebool -P kerberos_enabled 1
You can see the context of a file using the -Z option to lsP Policy governs the access confined processes have to these files. SELinux telnetd policy is very flexible allowing users to setup their telnetd processes in as secure a method as possible.
The following file types are defined for telnetd:
telnetd_exec_t
- Set files with the telnetd_exec_t type, if you want to transition an executable to the telnetd_t domain.
telnetd_keytab_t
- Set files with the telnetd_keytab_t type, if you want to treat the files as kerberos keytab files.
telnetd_tmp_t
- Set files with the telnetd_tmp_t type, if you want to store telnetd temporary files in the /tmp directories.
telnetd_var_run_t
- Set files with the telnetd_var_run_t type, if you want to store the telnetd files under the /run directory.
Note: File context can be temporarily modified with the chcon command. If you want to permanently change the file context you need to use the semanage fcontext command. This will modify the SELinux labeling database. You will need to use restorecon to apply the labels.
You can see the types associated with a port by using the following command:
semanage port -l
Policy governs the access confined processes have to these ports. SELinux telnetd policy is very flexible allowing users to setup their telnetd processes in as secure a method as possible.
The following port types are defined for telnetd:
Default Defined Ports: tcp 23
You can see the context of a process using the -Z option to psP Policy governs the access confined processes have to files. SELinux telnetd policy is very flexible allowing users to setup their telnetd processes in as secure a method as possible.
The following process types are defined for telnetd:
telnetd_t
Note: semanage permissive -a PROCESS_TYPE can be used to make a process type permissive. Permissive process types are not denied access by SELinux. AVC messages will still be generated.
The SELinux user type telnetd_t can manage files labeled with the following file types. The paths listed are the default paths for these file types. Note the processes UID still need to have DAC permissions.
initrc_var_run_t
/var/run/utmp
/var/run/random-seed
/var/run/runlevel.dir
/var/run/setmixer_flag
krb5_host_rcache_t
/var/cache/krb5rcache(/.*)?
/var/tmp/nfs_0
/var/tmp/host_0
/var/tmp/imap_0
/var/tmp/HTTP_23
/var/tmp/HTTP_48
/var/tmp/ldap_55
/var/tmp/ldap_487
/var/tmp/ldapmap1_0
security_t
/selinux
telnetd_tmp_t
telnetd_var_run_t
user_tmp_t
/var/run/user(/.*)?
/tmp/gconfd-.*
wtmp_t
/var/log/wtmp.*