How to find out If Program/Application is compiled with TCP Wrappers Or Not?

https://access.redhat.com/solutions/47176

 SOLUTION 已验证 - 已更新 2013年十一月17日04:12 - 

English 

环境

• Red Hat Enterprise Linux (All versions)
• tcp_wrappers

问题

• How to find out which application are compiled with tcp_wrapper support?
• How to find out If Program/Application is compiled with TCP Wrappers Or Not?

决议

Use ldd command to determine whether a given executable daemon /path/to/daemon supports TCP Wrapper.

Raw

 $ ldd /path/to/daemon | grep libwrap.so

If this command returns any output, then the daemon supports TCP Wrapper.

Raw

# ldd /usr/sbin/vsftpd | grep libwrap
libwrap.so.0 => /lib64/libwrap.so.o (0x000xxxxxxxx)

ldd is used to see if libwrap.so is a dependency or not. Some services don't use 'libwrap' library. For these services, execute following command.

Raw

# strings $(which <service_name>) | grep hosts
e.g.
hosts_access
/etc/hosts.allow
/etc/hosts.deny

If the results contain /etc/hosts.{allow,deny}, the service is handled by tcpwrapper.

NOTE: xinetd is a TCP wrapped super service. A service on xinetd can be restricted by xinetd with libwrap, even if the service program doesn't link to libwrap.so. Refer to another solution for the detail of xinetd.