1in.rshd(1M) System Administration Commands in.rshd(1M)
2
6 in.rshd, rshd - remote shell server
7
9 in.rshd [-k5eciU] [-s tos] [-S keytab] [-M realm]
10 [-L env_var] host.port
11
14 in.rshd is the server for the rsh(1) program. The server provides
15 remote execution facilities with authentication based on Kerberos V5 or
16 privileged port numbers.
17 in.rshd is invoked by inetd(1M) each time a shell service is requested.
20 When Kerberos V5 authentication is required (this can be set with Ker‐
23 beros-specific options listed below), the following protocol is initi‐
24 ated:
25 1. Check Kerberos V5 authentication.
27 2. Check authorization according to rules in
29 krb5_auth_rules(5).
30 3. A null byte is returned on the initial socket and the com‐
32 mand line is passed to the normal login shell of the user.
33 (The PATH variable is set to /usr/bin.) The shell inherits
34 the network connections established by in.rshd.
35 In order for Kerberos authentication to work, a host/<FQDN> Kerberos
38 principal must exist for each Fully Qualified Domain Name associated
39 with the in.rshd server. Each of these host/<FQDN> principals must have
40 a keytab entry in the /etc/krb5/krb5.keytab file on the in.rshd server.
41 An example principal might be:
42 host/bigmachine.eng.example.com
45 See kadmin(1M) or gkadmin(1M) for instructions on adding a principal to
48 a krb5.keytab file. See for a discussion of Kerberos authentication.
49 If Kerberos V5 authentication is not enabled, then in.rshd executes the
52 following protocol:
53 1. The server checks the client's source port. If the port is
55 not in the range 512-1023, the server aborts the connection.
56 The client's host address (in hex) and port number (in deci‐
57 mal) are the arguments passed to in.rshd.
58 2. The server reads characters from the socket up to a null ( )
60 byte. The resultant string is interpreted as an ASCII num‐
61 ber, base 10.
62 3. If the number received in step 2 is non-zero, it is inter‐
64 preted as the port number of a secondary stream to be used
65 for the stderr. A second connection is then created to the
66 specified port on the client's machine. The source port of
67 this second connection is also in the range 512-1023.
68 4. A null-terminated user name of at most 16 characters is
70 retrieved on the initial socket. This user name is inter‐
71 preted as the user identity on the client's machine.
72 5. A null terminated user name of at most 16 characters is
74 retrieved on the initial socket. This user name is inter‐
75 preted as a user identity to use on the server's machine.
76 6. A null terminated command to be passed to a shell is
78 retrieved on the initial socket. The length of the command
79 is limited by the upper bound on the size of the system's
80 argument list.
81 7. in.rshd then validates the user according to the following
83 steps. The remote user name is looked up in the password
84 file and a chdir is performed to the user's home directory.
85 If the lookup fails, the connection is terminated. If the
86 chdir fails, it does a chdir to / (root). If the user is not
87 the superuser, (user ID 0), and if the pam_rhosts_auth PAM
88 module is configured for authentication, the file
89 /etc/hosts.equiv is consulted for a list of hosts considered
90 "equivalent". If the client's host name is present in this
91 file, the authentication is considered successful. See the
92 SECURITY section below for a discussion of PAM authentica‐
93 tion.
94 If the lookup fails, or the user is the superuser, then the
96 file .rhosts in the home directory of the remote user is
97 checked for the machine name and identity of the user on the
98 client's machine. If this lookup fails, the connection is
99 terminated
100 8. A null byte is returned on the initial connection and the
102 command line is passed to the normal login shell of the
103 user. The PATH variable is set to /usr/bin. The shell inher‐
104 its the network connections established by in.rshd.
105
107 The following options are supported:
108 -5 Same as -k, for backwards compatibility
110 -c Requires Kerberos V5 clients to present a cryptographic
113 checksum of initial connection information like the name
114 of the user that the client is trying to access in the
115 initial authenticator. This checksum provides additionl
116 security by preventing an attacker from changing the ini‐
117 tial connection information. This option is mutually
118 exclusive with the -i option.
119 -e Requires the client to encrypt the connection.
122 -i Ignores authenticator checksums if provided. This option
125 ignores authenticator checksums presented by current Ker‐
126 beros clients to protect initial connection information.
127 Option -i is the opposite of option -c.
128 -k Allows Kerberos V5 authentication with the .k5login
131 access control file to be trusted. If this authentication
132 system is used by the client and the authorization check
133 is passed, then the user is allowed to log in.
134 -L env_var List of environment variables that need to be saved and
137 passed along.
138 -M realm Uses the indicated Kerberos V5 realm. By default, the
141 daemon will determine its realm from the settings in the
142 krb5.conf(4) file.
143 -s tos Sets the IP TOS option.
146 -S keytab Sets the KRB5 keytab file to use.
149 The/etc/krb5/krb5.keytab file is used by default.
150 -U Refuses connections that cannot be mapped to a name
153 through the getnameinfo(3SOCKET) function.
154
157 rshd and in.rshd are IPv6-enabled. See ip6(7P). IPv6 is not currently
158 supported with Kerberos V5 authentication.
159 The Kerberized rshd service runs on port 544 (kshell). The correspond‐
162 ing FMRI entry is: :
163 svc:/network/shell:kshell (rshd with kerberos (ipv4 only))
165
169 in.rshd uses pam(3PAM) for authentication, account management, and ses‐
170 sion management. The PAM configuration policy, listed through
171 /etc/pam.conf, specifies the modules to be used for in.rshd. Here is a
172 partial pam.conf file with entries for the rsh command using rhosts
173 authentication, UNIX account management, and session management module.
174 rsh auth required pam_rhosts_auth.so.1
179 rsh account required pam_unix_roles.so.1
181 rsh session required pam_unix_projects.so.1
182 rsh session required pam_unix_account.so.1
183 rsh session required pam_unix_session.so.1
185 If there are no entries for the rsh service, then the entries for the
189 "other" service are used. To maintain the authentication requirement
190 for in.rshd, the rsh entry must always be configured with the
191 pam_rhosts_auth.so.1 module.
192 in.rshd can authenticate using Kerberos V5 authentication or pam(3PAM).
195 For Kerberized rsh service, the appropriate PAM service name is krsh.
196
198 /etc/hosts.equiv
199 $HOME/.k5login File containing Kerberos principals that are
201 allowed access.
202 /etc/krb5/krb5.conf Kerberos configuration file.
205
208 See attributes(5) for descriptions of the following attributes:
209 ┌─────────────────────────────┬─────────────────────────────┐
214 │ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
215 ├─────────────────────────────┼─────────────────────────────┤
216 │Availability │SUNWrcmds │
217 └─────────────────────────────┴─────────────────────────────┘
218
220 rsh(1), svcs(1), gkadmin(1M), inetadm(1M), inetd(1M), kadmin(1M),
221 svcadm(1M), pam(3PAM), getnameinfo(3SOCKET), hosts(4), krb5.conf(4),
222 pam.conf(4), attributes(5), environ(5), krb5_auth_rules(5), pam_auth‐
223 tok_check(5), pam_authtok_get(5), pam_authtok_store(5), pam_dhkeys(5),
224 pam_passwd_auth(5), pam_rhosts_auth(5), pam_unix_account(5),
225 pam_unix_auth(5), pam_unix_session(5), smf(5), ip6(7P)
226
231 The following diagnostic messages are returned on the connection asso‐
232 ciated with stderr, after which any network connections are closed. An
233 error is indicated by a leading byte with a value of 1 in step 8 above
234 (0 is returned above upon successful completion of all the steps prior
235 to the command execution).
236 locuser too long
238 The name of the user on the client's machine is longer than 16
240 characters.
241 remuser too long
244 The name of the user on the remote machine is longer than 16 char‐
246 acters.
247 command too long
250 The command line passed exceeds the size of the argument list (as
252 configured into the system).
253 Hostname for your address unknown.
256 No entry in the host name database existed for the client's
258 machine.
259 Login incorrect.
262 No password file entry for the user name existed.
264 Permission denied.
267 The authentication procedure described above failed.
269 Can't make pipe.
272 The pipe needed for the stderr was not created.
274 Try again.
277 A fork by the server failed.
279
282 The authentication procedure used here assumes the integrity of each
283 client machine and the connecting medium. This is insecure, but it is
284 useful in an "open" environment.
285 A facility to allow all data exchanges to be encrypted should be
288 present.
289 The pam_unix(5) module is no longer supported. Similar functionality is
292 provided by pam_authtok_check(5), pam_authtok_get(5), pam_auth‐
293 tok_store(5), pam_dhkeys(5), pam_passwd_auth(5), pam_unix_account(5),
294 pam_unix_auth(5), and pam_unix_session(5).
295 The in.rshd service is managed by the service management facility,
298 smf(5), under the service identifier:
299 svc:/network/shell:default
301 Administrative actions on this service, such as enabling, disabling, or
306 requesting restart, can be performed using svcadm(1M). Responsibility
307 for initiating and restarting this service is delegated to inetd(1M).
308 Use inetadm(1M) to make configuration changes and to view configuration
309 information for this service. The service's status can be queried using
310 the svcs(1) command.
311SunOS 5.11 10 Nov 2005 in.rshd(1M)