1 IN.RLOGIND(1M) Maintenance Commands IN.RLOGIND(1M) 2 3 NAME 4 in.rlogind, rlogind - remote login server 5 6 SYNOPSIS 7 /usr/sbin/in.rlogind [-k5eExXciPp] [-s tos] [-S keytab] 8 [-M realm] 9 10 11 DESCRIPTION 12 in.rlogind is the server for the rlogin(1) program. The server 13 provides a remote login facility with authentication based on Kerberos 14 V5 or privileged port numbers. 15 16 17 in.rlogind is invoked by inetd(1M) when a remote login connection is 18 established. When Kerberos V5 authentication is required (see option -k 19 below), the authentication sequence is as follows: 20 21 o Check Kerberos V5 authentication. 22 23 o Check authorization according to the rules in 24 krb5_auth_rules(5). 25 26 o Prompt for a password if any checks fail and /etc/pam.conf 27 is configured to do so. 28 29 30 In order for Kerberos authentication to work, a host/<FQDN> Kerberos 31 principal must exist for each Fully Qualified Domain Name associated 32 with the in.rlogind server. Each of these host/<FQDN> principals must 33 have a keytab entry in the /etc/krb5/krb5.keytab file on the in.rlogind 34 server. An example principal might be: 35 36 37 host/bigmachine.eng.example.com 38 39 40 See kadmin(1M) for instructions on adding a principal to a krb5.keytab 41 file. See for a discussion of Kerberos authentication. 42 43 44 If Kerberos V5 authentication is not enabled, then the authentication 45 procedure follows the standard rlogin protocol: 46 47 o The server checks the client's source port. If the port is 48 not in the range 512-1023, the server aborts the connection. 49 50 o The server checks the client's source address. If an entry 51 for the client exists in both /etc/hosts and 52 /etc/hosts.equiv, a user logging in from the client is not 53 prompted for a password. If the address is associated with a 54 host for which no corresponding entry exists in /etc/hosts, 55 the user is prompted for a password, regardless of whether 56 or not an entry for the client is present in 57 /etc/hosts.equiv. See hosts(4) and hosts.equiv(4). 58 59 60 Once the source port and address have been checked, in.rlogind 61 allocates a pseudo-terminal and manipulates file descriptors so that 62 the subsidiary half of the pseudo-terminal becomes the stdin, stdout, 63 and stderr for a login process. The login process is an instance of 64 the login(1) program, invoked with the -r. 65 66 67 The login process then proceeds with the pam(3PAM) authentication 68 process. See SECURITY below. If automatic authentication fails, it 69 reprompts the user to login. 70 71 72 The parent of the login process manipulates the manager side of the 73 pseudo-terminal, operating as an intermediary between the login process 74 and the client instance of the rlogin program. In normal operation, a 75 packet protocol is invoked to provide Ctrl-S and Ctrl-Q type facilities 76 and propagate interrupt signals to the remote programs. The login 77 process propagates the client terminal's baud rate and terminal type, 78 as found in the environment variable, TERM. 79 80 OPTIONS 81 The following options are supported: 82 83 -5 84 Same as -k, for backwards compatibility. 85 86 87 -c 88 Requires Kerberos V5 clients to present a cryptographic 89 checksum of initial connection information like the name 90 of the user that the client is trying to access in the 91 initial authenticator. This checksum provides additionl 92 security by preventing an attacker from changing the 93 initial connection information. This option is mutually 94 exclusive with the -i option. 95 96 97 -e 98 Creates an encrypted session. 99 100 101 -E 102 Same as -e, for backwards compatibility. 103 104 105 -i 106 Ignores authenticator checksums if provided. This option 107 ignores authenticator checksums presented by current 108 Kerberos clients to protect initial connection 109 information. Option -i is the opposite of option -c. 110 111 112 -k 113 Allows Kerberos V5 authentication with the .k5login access 114 control file to be trusted. If this authentication system 115 is used by the client and the authorization check is 116 passed, then the user is allowed to log in. 117 118 119 -M realm 120 Uses the indicated Kerberos V5 realm. By default, the 121 daemon will determine its realm from the settings in the 122 krb5.conf(4) file. 123 124 125 -p 126 Prompts for authentication only if other authentication 127 checks fail. 128 129 130 -P 131 Prompts for a password in addition to other authentication 132 methods. 133 134 135 -s tos 136 Sets the IP TOS option. 137 138 139 -S keytab 140 Sets the KRB5 keytab file to use. The 141 /etc/krb5/krb5.keytab file is used by default. 142 143 144 -x 145 Same as -e, for backwards compatibility. 146 147 148 -X 149 Same as -e, for backwards compatibility. 150 151 152 USAGE 153 rlogind and in.rlogind are IPv6-enabled. See ip6(7P). IPv6 is not 154 currently supported with Kerberos V5 authentication. 155 156 157 Typically, Kerberized rlogin service runs on port 543 (klogin) and 158 Kerberized, encrypted rlogin service runs on port 2105 (eklogin). The 159 corresponding FMRI entries are: 160 161 svc:/network/login:klogin (rlogin with kerberos) 162 svc:/network/login:eklogin (rlogin with kerberos and encryption) 163 164 165 166 SECURITY 167 in.rlogind uses pam(3PAM) for authentication, account management, and 168 session management. The PAM configuration policy, listed through 169 /etc/pam.conf, specifies the modules to be used for in.rlogind. Here 170 is a partial pam.conf file with entries for the rlogin command using 171 the "rhosts" and UNIX authentication modules, and the UNIX account, 172 session management, and password management modules. 173 174 175 176 177 rlogin auth sufficient pam_rhosts_auth.so.1 178 rlogin auth requisite pam_authtok_get.so.1 179 rlogin auth required pam_dhkeys.so.1 180 rlogin auth required pam_unix_auth.so.1 181 182 rlogin account required pam_unix_roles.so.1 183 rlogin account required pam_unix_projects.so.1 184 rlogin account required pam_unix_account.so.1 185 186 rlogin session required pam_unix_session.so.1 187 188 189 190 With this configuration, the server checks the client's source address. 191 If an entry for the client exists in both /etc/hosts and 192 /etc/hosts.equiv, a user logging in from the client is not prompted for 193 a password. If the address is associated with a host for which no 194 corresponding entry exists in /etc/hosts, the user is prompted for a 195 password, regardless of whether or not an entry for the client is 196 present in /etc/hosts.equiv. See hosts(4) and hosts.equiv(4). 197 198 199 When running a Kerberized rlogin service (with or without the 200 encryption option), the pam service name that should be used is 201 "krlogin". 202 203 204 If there are no entries for the rlogin service, then the entries for 205 the "other" service will be used. If multiple authentication modules 206 are listed, then the user may be prompted for multiple passwords. 207 Removing the pam_rhosts_auth.so.1 entry will disable the 208 /etc/hosts.equiv and ~/.rhosts authentication protocol and the user 209 would always be forced to type the password. The sufficient flag 210 indicates that authentication through the pam_rhosts_auth.so.1 module 211 is sufficient to authenticate the user. Only if this authentication 212 fails is the next authentication module used. 213 214 SEE ALSO 215 login(1), svcs(1), rlogin(1), in.rshd(1M), inetadm(1M), inetd(1M), 216 kadmin(1M), svcadm(1M), pam(3PAM), hosts(4), hosts.equiv(4), 217 krb5.conf(4), pam.conf(4), attributes(5), environ(5), 218 krb5_auth_rules(5), pam_authtok_check(5), pam_authtok_get(5), 219 pam_authtok_store(5), pam_dhkeys(5), pam_passwd_auth(5), 220 pam_unix_account(5), pam_unix_auth(5), pam_unix_session(5), smf(5) 221 222 223 224 DIAGNOSTICS 225 All diagnostic messages are returned on the connection associated with 226 the stderr, after which any network connections are closed. An error is 227 indicated by a leading byte with a value of 1. 228 229 Hostname for your address unknown. 230 231 No entry in the host name database existed for the client's 232 machine. 233 234 235 Try again. 236 237 A fork by the server failed. 238 239 240 /usr/bin/sh: ... 241 242 The user's login shell could not be started. 243 244 245 NOTES 246 The authentication procedure used here assumes the integrity of each 247 client machine and the connecting medium. This is insecure, but it is 248 useful in an ``open'' environment. 249 250 251 A facility to allow all data exchanges to be encrypted should be 252 present. 253 254 255 The pam_unix(5) module is no longer supported. Similar functionality is 256 provided by pam_authtok_check(5), pam_authtok_get(5), 257 pam_authtok_store(5), pam_dhkeys(5), pam_passwd_auth(5), 258 pam_unix_account(5), pam_unix_auth(5), and pam_unix_session(5). 259 260 261 The in.rlogind service is managed by the service management facility, 262 smf(5), under the service identifier: 263 264 svc:/network/login:rlogin (rlogin) 265 svc:/network/login:klogin (rlogin with kerberos) 266 svc:/network/login:eklogin (rlogin with kerberos and encryption) 267 268 269 270 271 Administrative actions on this service, such as enabling, disabling, or 272 requesting restart, can be performed using svcadm(1M). Responsibility 273 for initiating and restarting this service is delegated to inetd(1M). 274 Use inetadm(1M) to make configuration changes and to view configuration 275 information for this service. The service's status can be queried using 276 the svcs(1) command. 277 278 February 5, 2022 IN.RLOGIND(1M)