161437Sbostic.\" Copyright (c) 1983, 1991, 1993 261437Sbostic.\" The Regents of the University of California. All rights reserved. 319000Smckusick.\" 443769Strent.\" %sccs.include.redist.man% 519000Smckusick.\" 6*67329Sah.\" @(#)rexecd.8 8.3 (Berkeley) 06/01/94 735734Sbostic.\" 847462Scael.Dd 947462Scael.Dt REXECD 8 1047462Scael.Os BSD 4.2 1147462Scael.Sh NAME 1247462Scael.Nm rexecd 1347462Scael.Nd remote execution server 1447462Scael.Sh SYNOPSIS 1547462Scael.Nm rexecd 1647462Scael.Sh DESCRIPTION 1747462Scael.Nm Rexecd 1819000Smckusickis the server for the 1947462Scael.Xr rexec 3 2019000Smckusickroutine. The server provides remote execution facilities 2127903Slepreauwith authentication based on user names and 2219000Smckusickpasswords. 2347462Scael.Pp 2447462Scael.Nm Rexecd 2519000Smckusicklistens for service requests at the port indicated in 2619000Smckusickthe ``exec'' service specification; see 2747462Scael.Xr services 5 . 2819000SmckusickWhen a service request is received the following protocol 2919000Smckusickis initiated: 3047462Scael.Bl -enum 3147462Scael.It 3219000SmckusickThe server reads characters from the socket up 3347462Scaelto a NUL 3447462Scael.Pq Ql \e0 3547462Scaelbyte. The resultant string is 3647462Scaelinterpreted as an 3747462Scael.Tn ASCII 3847462Scaelnumber, base 10. 3947462Scael.It 4019000SmckusickIf the number received in step 1 is non-zero, 4119000Smckusickit is interpreted as the port number of a secondary 4219000Smckusickstream to be used for the 4347462Scael.Em stderr . 4419000SmckusickA second connection is then created to the specified 4519000Smckusickport on the client's machine. 4647462Scael.It 4747462ScaelA NUL terminated user name of at most 16 characters 4819000Smckusickis retrieved on the initial socket. 4947462Scael.It 5047462ScaelA NUL terminated, unencrypted password of at most 5119000Smckusick16 characters is retrieved on the initial socket. 5247462Scael.It 5347462ScaelA NUL terminated command to be passed to a 5419000Smckusickshell is retrieved on the initial socket. The length of 5519000Smckusickthe command is limited by the upper bound on the size of 5619000Smckusickthe system's argument list. 5747462Scael.It 5847462Scael.Nm Rexecd 5919000Smckusickthen validates the user as is done at login time 6019000Smckusickand, if the authentication was successful, changes 6119000Smckusickto the user's home directory, and establishes the user 6219000Smckusickand group protections of the user. 6319000SmckusickIf any of these steps fail the connection is 6419000Smckusickaborted with a diagnostic message returned. 6547462Scael.It 6647462ScaelA NUL byte is returned on the initial socket 6719000Smckusickand the command line is passed to the normal login 6819000Smckusickshell of the user. The 6919000Smckusickshell inherits the network connections established 7019000Smckusickby 7147462Scael.Nm rexecd . 7247462Scael.El 7347462Scael.Sh DIAGNOSTICS 7427903SlepreauExcept for the last one listed below, 7527903Slepreauall diagnostic messages are returned on the initial socket, 7619000Smckusickafter which any network connections are closed. 7719000SmckusickAn error is indicated by a leading byte with a value of 7819000Smckusick1 (0 is returned in step 7 above upon successful completion 7919000Smckusickof all the steps prior to the command execution). 8047462Scael.Pp 8147462Scael.Bl -tag -width Ds 8247462Scael.It Sy username too long 8319000SmckusickThe name is 8419000Smckusicklonger than 16 characters. 8547462Scael.It Sy password too long 8619000SmckusickThe password is longer than 16 characters. 8747462Scael.It Sy command too long 8819000SmckusickThe command line passed exceeds the size of the argument 8919000Smckusicklist (as configured into the system). 9047462Scael.It Sy Login incorrect. 9119000SmckusickNo password file entry for the user name existed. 9247462Scael.It Sy Password incorrect. 9365103SmckusickThe wrong password was supplied. 94*67329Sah.ne 1i 9547462Scael.It Sy \&No remote directory. 9619000SmckusickThe 9747462Scael.Xr chdir 9819000Smckusickcommand to the home directory failed. 9947462Scael.It Sy Try again. 10019000SmckusickA 10147462Scael.Xr fork 10219000Smckusickby the server failed. 10347462Scael.It Sy <shellname>: ... 10419000SmckusickThe user's login shell could not be started. 10527903SlepreauThis message is returned 10627903Slepreauon the connection associated with the 10747462Scael.Em stderr , 10827903Slepreauand is not preceded by a flag byte. 10947462Scael.El 11047462Scael.Sh SEE ALSO 11147462Scael.Xr rexec 3 11247462Scael.Sh BUGS 11319000SmckusickIndicating ``Login incorrect'' as opposed to ``Password incorrect'' 11419000Smckusickis a security breach which allows people to probe a system for users 11519000Smckusickwith null passwords. 11647462Scael.Pp 11727903SlepreauA facility to allow all data and password exchanges to be encrypted should be 11819000Smckusickpresent. 11947462Scael.Sh HISTORY 12047462ScaelThe 12147462Scael.Nm 12247462Scaelcommand appeared in 12347462Scael.Bx 4.2 . 124