Helper program to bind sockets to privileged ports without root
/usr/lib/authbind/helper addr4-hex port-hex <socket
/usr/lib/authbind/helper addr6-hex port-hex 6 <socket
helper is the program used by 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 authbind. Its standard input should be a TCP/IP socket, and it should be passed two or three arguments.
The arguments are the address and port number, respectively, to which the caller desires that the socket be bound, and the address family (ommitted for IPv4; the fixed string 6 for IPv6). addr4-hex and port-hex should be hex strings, without leading 0x, of exactly the right length (8 and 4 digits, respectively), being a pair of hex digits for each byte in the address or port number when expressed in host byte order. For example, the port argument is the result of something like sprintf(arg, %04X , sin.sin_port). addr6-hex should be a string of 32 hex digits, being a pair for each byte in the address, in network byte order.
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 helper.
authbind and this manpage were written by Ian Jackson. They are Copyright (C)1998,2012 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.