authbind-helper - helper program to bind sockets to privileged ports without root
I /usr/lib/authbind/helper addr-hex port-hex < socket
helper is the program used by R libauthbind , which is in turn used by authbind to allow programs which do not or should not run as root to bind to low-numbered ports in a controlled way. See authbind(1).
It may also be used standalone, i.e. without assistance from R authbind . Its standard input should be a TCP/IP socket, and it should be passed two arguments.
The arguments are the address and port number, respectively, to which the caller desires that the socket be bound. They should be hex strings, without leading R 0x , of exactly the right length (8 and 4 digits, respectively), being a pairs of hex digits for each byte in the address or port number when expressed in network byte order.
helper will not bind to ports 512 and onwards, because programs like rshd expect these to be used for outgoing connections, so allowing a user to bind to one of these would open up security hole(s).
helper will exit with code 0 on success.
If possible, helper will return an appropriate errno value as its exit status. If this is not possible it may exit with status 255 or with an exit status corresponding to ENOSYS (Function not implemented).
See authbind(1) for details of the access control regime implemented by R helper .
authbind and this manpage were written by Ian Jackson. They are Copyright (C)1998 by him and released under the GNU General Public Licence; there is NO WARRANTY. See /usr/doc/authbind/copyright and /usr/doc/copyright/GPL for details.