Host name syntax
Note: This special syntax is generally not used from the user interfaces of wc3270 or wx3270, except in scripts or at the x3270> prompt. Those user interfaces allow these options to be specified separately, and construct a properly-formatted host name from them.
Basic syntax
The basic syntax is:
- [prefix:...] host [:port] [=accept-name]
Prefixes
A prefix sets an option for a single host session, rather than for all sessions created by the emulator. A prefix is a single letter, separated from the host name by a colon (:), e.g.:
L:host.foo.com
To specify multiple prefixes, separate each of them with a colon, e.g.:
L:Y:host.foo.com
- A - NVT-only session
- Marks the host as supporting NVT mode only. The emulator does not attempt to negotiate 3270 mode, and defaults the terminal name to
xterm(if a monochrome display) orxterm-color(if a color display, New in 4.2). - B - No-op
- Formerly caused a change in bind-unlock behavior, but this has now been subsumed by the default value of the bindUnlock resource.
- C - CICS host
- Disables the automatic keyboard lock after connecting to a host, waiting for the host to format the screen. This is needed for CICS hosts, for example, which do not initially format the screen.
- L - Use a TLS tunnel
- Causes the emulator to set up a TLS tunnel for the host connection. TLS negotiation happens before TELNET negotiation, so the entire session is encrypted.
- N - Disable TN3270E
- Disables TN3270E mode. If the host attempts to negotiate TN3270E when this prefix is in use, the emulator will reject it.
- T - No-TELNET host
- Disables the TELNET protocol for the session. The emulator will no longer treat the TELNET IAC character (0xff) specially.
- Y - Disable TLS host certificate checking
- Disables TLS host certificate checking. It overrides the value of the verifyHostCert resource.
Host
The host is either a fully-qualified domain name (e.g., foo.bar.com) or a numeric address in either IPv4 dotted-decimal or IPv6 hexadecimal format. A numeric IPv6 addres must be surrounded by square-bracket characters, e.g., [100:200::1], to keep the colon characters from being misinterpreted.
Port
The optional port is a number separated from the host name by a colon. It overrides the default value of 23 (the TELNET port).
Accept-name
The optional accept-name is separated from the host and optional port by an equals sign (=). It overrides the value of the acceptHostname resource, specifying a name to match against the host's TLS certificate.
URI syntax
New in 4.4
A host can also be specified using a Uniform Resource Identifier (URI), e.g., tn3270://host.foo.com
URIs use the following standard syntax:
- scheme :// [username[:password]@] host [:port] [?query]
x3270 supports the following URI schemes:
| Query Options | |||||||
|---|---|---|---|---|---|---|---|
| Scheme | Meaning | Default Terminal Name |
Default Port |
?accepthostname | ?lu | ?verifyhostcert | ?waitoutput |
| telnet | TELNET protocol | xterm | 23 | ✓ | |||
| telnets | Secure TELNET protocol TLS tunnel created |
xterm | 992 | ✓ | ✓ | ✓ | |
| tn3270 | TN3720 or TN3270E protocol | IBM-3279-2-E | 23 | ✓ | ✓ | ||
| tn3270s | Secure TN3720/TN3270E protocol TLS tunnel created |
IBM-3279-2-E | 992 | ✓ | ✓ | ✓ | ✓ |
Query Options
- ?accepthostname=name
- Specifies the subject name to compare against the host TLS certificate.
- ?lu=lu-list
- Specifies a Logical Unit (LU) name or a comma-separated list of Logical Unit names to connect to.
- ?verifyhostcert=false
- If set to false, do not verify the host TLS certificate. Equivalent to the Y: prefix.
- ?waitoutput=false
- If set to false, do not wait for the host to produce output before unlocking the keyboard the first time. Equivalent to the C: prefix.
Notes
The telnet and telnets schemes are equivalent to using the A: prefix.
Passwords are always ignored. Fragments are not allowed.
The default port associated with a URI overrides the port resource.
Examples
Connect to foo.bar.com in 3270 mode, without a TLS tunnel, on port 23.
foo.bar.com tn3270://foo.bar.com
Connect to foo.bar.com in 3270 mode, with a TLS tunnel but not verifying the host certificate, on port 9100.
L:Y:foo.bar.com:9100 tn3270s://foo.bar.com:9011?verifyhostcert=false
Connect to IPv4 address 1.2.3.4 in 3270 mode on port 23.
1.2.3.4 tn3270://1.2.3.4
Connect to IPv6 address 100:200::1 in 3270 mode on port 23.
[100:200::1] tn3270://[100:200::1]
Connect to IPv6 address 100:200::1, in 3270 mode, on port 9100 with a TLS tunnel, using myhost to match the name from the host's TLS certificate.
L:[100:200::1]:9100=myhost tn3270s://[100:200::1]:9100?accepthostname=myhost
Connect to host foo.bar.com in 3270 mode, in port 23, specifying Logical units ABC123 and FOO999.
ABC123,[email protected] tn3270://foo.bar.com?lu=ABC123,FOO999
Connect to host foo.bar.com in NVT mode
A:foo.bar.com telnet://foo.bar.com
Connect to foo.bar.com in NVT mode, with a TLS tunnel on port 992.
L:foo.bar.com:992 telnets://foo.bar.com
Connect to foo.bar.com in NVT mode, specifying username bob.
telnet://[email protected]