Getting Data in and out of your AS/400 - Revision history

PoC: De-whichified

2020-03-12T21:59:57Z

De-whichified

PoC: /* A word on data encryption */ Rewrote

2019-03-04T22:57:01Z

A word on data encryption: Rewrote

← Older revision		Revision as of 00:57, 5 March 2019
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	=== A word on data encryption ===		=== A word on data encryption ===
	The AS/400 actually ''can'' encrypt data. The OS supports telnet/ssl and https. Given the rapid development in cryptographic knowledge, the crypto support in older OS/400 versions is so horribly outdated and possibly crippled by former US export restrictions that it's best to stop even considering to utilize crypto on the box itself.		The AS/400 actually ''can'' encrypt data. The OS supports telnet/ssl and https. Given the rapid development in cryptographic knowledge, the crypto support in older OS/400 versions is so horribly outdated and possibly crippled by former US export restrictions that it's best to stop even considering to utilize crypto on the box itself. Even worse, crypto implementations on common systems may fail to negotiate a connection, because old, weak and known-to-be-broken algorithms offered by OS/400 aren't accepted and newer algorithms aren't supported by old OS/400 releases.

	If one likes the idea of exposing AS/400 services to the internet, it's best to use proxy services in front of the machine. A Linux box with a recent Distro and Apache or Nginx can ~~talk~~ SSL to the outside world and use plain http to the AS/400 in the ~~internal~~ (hopefully) secure internal LAN.<br />		If one still likes the idea of exposing AS/400 services to the internet, it's best to use proxy services in front of the machine. A Linux box with a recent Distro and Apache or Nginx can offer SSL services to the outside world and use plain http to talk to the AS/400 in the (hopefully) secure internal LAN.<br />
	Same goes for tn5250 access: Stunnel works fine in the same manner: telnet/ssl to the outside world, plain telnet inside.		Same goes for tn5250 access: Stunnel works fine in the same manner, telnet/ssl to the outside world, plain telnet inside.

	It's very likely that a near-20-year-old OS/400 may have security holes. Searching the CVE database reveals not all too much but that maybe because the AS/400 is not exactly a well-known hacker target. Please keep this in mind when deciding to expose AS/400 services to the Internet.		It's very likely that a near-20-year-old OS/400 may have security holes. Searching the CVE database reveals not all too much but that maybe because the AS/400 is not exactly a well-known hacker target. Please keep this in mind when deciding to expose AS/400 services to the Internet.

PoC: /* Charset handling */ Better

2019-03-04T22:50:53Z

Charset handling: Better

← Older revision		Revision as of 00:50, 5 March 2019
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	=== Charset handling ===		=== Charset handling ===
	An obstacle to keep in mind is the the different character set of the AS/400 vs. todays ~~conventional~~ systems. The AS/400 utilizes the [[wikipedia:EBDIC\|EBCDIC]] character set which was invented by IBM in the punch card age, whereas common platforms utilize character sets based on [[wikipedia:ASCII\|ASCII]] and it's multibyte successors.		An obstacle to keep in mind is the the different character set of the AS/400 vs. todays common systems. The AS/400 utilizes the [[wikipedia:EBDIC\|EBCDIC]] character set which was invented by IBM in the punch card age, whereas common platforms utilize character sets based on [[wikipedia:ASCII\|ASCII]] and it's multibyte successors.

	Terminal access, FTP mode ASCII transfers<ref>This comes in handy when handling large amounts of source code.</ref> and ODBC do the necessary conversions invisibly in the background. Users have no need to care. Lpr does this when ''host transform'' is enabled in the printer queue configuration. NFS does no conversation and handles everything as binary data.		Terminal access, FTP mode ASCII transfers<ref>This comes in handy when handling large amounts of source code.</ref> and ODBC do the necessary conversions invisibly in the background. Users have no need to care. Lpr does this when ''host transform'' is enabled in the printer queue configuration. NFS does no conversation and handles everything as binary data.

	Modern ~~conventional~~ systems utilize UTF-8 as character set. Special chars will be encoded with two or more Bytes, while as ASCII utilizes only a single Byte.<br />		Modern common systems utilize UTF-8 as character set. Special chars will be encoded with two or more Bytes, while as ASCII utilizes only a single Byte.<br />
	Documentation for OS/400 mentions DBCS, Double-Byte Character Support, which is the IBM-Flavor of UTF-8. It seems that this support needs a special installation media set of OS/400.		Documentation for OS/400 mentions DBCS, Double-Byte Character Support, which is the IBM-Flavor of UTF-8. It seems that this support needs a special installation media set of OS/400.

PoC: /* Charset handling */ Better

2019-03-04T22:50:11Z

Charset handling: Better

← Older revision		Revision as of 00:50, 5 March 2019
Line 69:		Line 69:

	=== Charset handling ===		=== Charset handling ===
	An obstacle to keep in mind is the the different character set of the AS/400 vs. todays conventional systems. The AS/400 utilizes the [[wikipedia:EBDIC\|EBCDIC]] character set which was invented by IBM in the punch card age, whereas ~~conventional~~ platforms utilize character sets based on [[wikipedia:ASCII\|ASCII]] and it's multibyte successors.		An obstacle to keep in mind is the the different character set of the AS/400 vs. todays conventional systems. The AS/400 utilizes the [[wikipedia:EBDIC\|EBCDIC]] character set which was invented by IBM in the punch card age, whereas common platforms utilize character sets based on [[wikipedia:ASCII\|ASCII]] and it's multibyte successors.

	Terminal access, FTP mode ASCII transfers<ref>This comes in handy when handling large amounts of source code.</ref> and ODBC do the necessary conversions invisibly in the background. Users have no need to care. Lpr does this when ''host transform'' is enabled in the printer queue configuration. NFS does no conversation and handles everything as binary data.		Terminal access, FTP mode ASCII transfers<ref>This comes in handy when handling large amounts of source code.</ref> and ODBC do the necessary conversions invisibly in the background. Users have no need to care. Lpr does this when ''host transform'' is enabled in the printer queue configuration. NFS does no conversation and handles everything as binary data.

PoC: /* Communication options of the AS/400 */ Reworked

2019-03-04T22:47:03Z

Communication options of the AS/400: Reworked

← Older revision		Revision as of 00:47, 5 March 2019
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	* IPX.		* IPX.

	It is not clear if the ''NetServer''-feature<ref>Basically a piece of software which provides NetBIOS-Services: File Sharing and Printing.</ref> also provides support for [[wikipedia:NetBIOS Frames protocol\|NetBIOS Frames protocol]], and which releases of OS/400 support this, if any.		It is not clear if the ''NetServer'' feature<ref>Basically a piece of software which provides NetBIOS-Services: File Sharing and Printing. Kind of ''Samba from IBM''.</ref> also provides support for [[wikipedia:NetBIOS Frames protocol\|NetBIOS Frames protocol]], and which releases of OS/400 support this, if any.

	Additionally with the so called ''AnyNet''-feature, OS/400 allows any of the above mentioned protocols be encapsulated in any other of the above. For that, it's possible to transfer SNA traffic across LAN segments and over WAN/VPNs built on IP. In fact, the AS/400 must (and thus can) act as an IP and IPX router between separate network segments.<br />		Additionally with the so called ''AnyNet''-feature, OS/400 allows any of the above mentioned protocols be encapsulated in any other of the above. For that, it's possible to transfer SNA traffic across LAN segments and over WAN/VPNs built on IP. In fact, the AS/400 must (and thus can) act as an IP and IPX router between separate network segments to be able to do this encapsulation.<br />
	This facility has been superseded by the ''Enterprise Extender'' feature, which only permits the extension of SNA networks over IP networks. Routing and Encapsulation Support was shifted to special multiprotocol routers.		This facility has been superseded by the ''Enterprise Extender'' feature, which only permits the extension of SNA networks over IP networks. Routing and Encapsulation Support for other protocol combinations was shifted to special multiprotocol routers.

	Newer releases also support IPv6.		Newer releases also support IPv6.

PoC at 17:19, 31 December 2018

2018-12-31T17:19:30Z

← Older revision		Revision as of 19:19, 31 December 2018
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	== Footnotes ==		== Footnotes ==
	<references />		<references />

			[[Category: Basic Knowledge]]

PoC: /* Charset handling */ Better

2018-12-31T16:05:09Z

Charset handling: Better

← Older revision		Revision as of 18:05, 31 December 2018
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	Documentation for OS/400 mentions DBCS, Double-Byte Character Support, which is the IBM-Flavor of UTF-8. It seems that this support needs a special installation media set of OS/400.		Documentation for OS/400 mentions DBCS, Double-Byte Character Support, which is the IBM-Flavor of UTF-8. It seems that this support needs a special installation media set of OS/400.

	If the client for above mentioned services supports local conversion, there should be no ~~conversion problem~~ for standard characters and most umlauts from Single- to Double-Byte and vice versa. This is the case with most tn5250 emulators.		If the client for above mentioned services supports local conversion, there should be no problems for standard characters and most umlauts from Single- to Double-Byte and vice versa. This is the case with most tn5250 emulators.

	If the AS/400 in a Single-Byte Character-Set Installation is supposed to do the conversion, one cannot utilize UTF-8 on the client side but must make sure to handle data with the Latin1 (ISO-8859-1) Code Page. This is the case with FTP/ASCII transfers, and LPR with host transform.		If the AS/400 in a Single-Byte Character-Set Installation is supposed to do the conversion, one cannot utilize UTF-8 on the client side but must make sure to handle data with the Latin1 (ISO-8859-1) Code Page. This is the case with FTP/ASCII transfers, and LPR with host transform.

PoC: /* Charset handling */ Edit

2018-12-31T16:04:01Z

Charset handling: Edit

← Older revision		Revision as of 18:04, 31 December 2018
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	Terminal access, FTP mode ASCII transfers<ref>This comes in handy when handling large amounts of source code.</ref> and ODBC do the necessary conversions invisibly in the background. Users have no need to care. Lpr does this when ''host transform'' is enabled in the printer queue configuration. NFS does no conversation and handles everything as binary data.		Terminal access, FTP mode ASCII transfers<ref>This comes in handy when handling large amounts of source code.</ref> and ODBC do the necessary conversions invisibly in the background. Users have no need to care. Lpr does this when ''host transform'' is enabled in the printer queue configuration. NFS does no conversation and handles everything as binary data.

	Modern conventional systems utilize UTF-8 as character set. Special chars will be encoded with two or more Bytes, while as ASCII utilizes only a single Byte.		Modern conventional systems utilize UTF-8 as character set. Special chars will be encoded with two or more Bytes, while as ASCII utilizes only a single Byte.<br />

	Documentation for OS/400 mentions DBCS, Double-Byte Character Support, which is the IBM-Flavor of UTF-8. It seems that this support needs a special installation media set of OS/400.		Documentation for OS/400 mentions DBCS, Double-Byte Character Support, which is the IBM-Flavor of UTF-8. It seems that this support needs a special installation media set of OS/400.

PoC: /* Charset handling */ Typo

2018-12-31T16:02:49Z

Charset handling: Typo

← Older revision		Revision as of 18:02, 31 December 2018
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	=== Charset handling ===		=== Charset handling ===
	An obstacle to keep in mind ~~are~~ the the different character ~~sets~~ of the AS/400 vs. todays conventional systems. The AS/400 utilizes the [[wikipedia:EBDIC\|EBCDIC]] character set which was invented by IBM in the punch card age, whereas conventional platforms utilize character sets based on [[wikipedia:ASCII\|ASCII]] and it's multibyte successors.		An obstacle to keep in mind is the the different character set of the AS/400 vs. todays conventional systems. The AS/400 utilizes the [[wikipedia:EBDIC\|EBCDIC]] character set which was invented by IBM in the punch card age, whereas conventional platforms utilize character sets based on [[wikipedia:ASCII\|ASCII]] and it's multibyte successors.

	Terminal access, FTP mode ASCII transfers<ref>This comes in handy when handling large amounts of source code.</ref> and ODBC do the necessary conversions invisibly in the background. Users have no need to care. Lpr does this when ''host transform'' is enabled in the printer queue configuration. NFS does no conversation and handles everything as binary data.		Terminal access, FTP mode ASCII transfers<ref>This comes in handy when handling large amounts of source code.</ref> and ODBC do the necessary conversions invisibly in the background. Users have no need to care. Lpr does this when ''host transform'' is enabled in the printer queue configuration. NFS does no conversation and handles everything as binary data.

PoC: /* The AS/400 in a modern network */ +Link

2018-12-31T16:01:53Z

The AS/400 in a modern network: +Link

← Older revision		Revision as of 18:01, 31 December 2018
Line 61:		Line 61:
	ODBC is also a nice way to utilize the AS/400 green screen interface basically as database file content editor, while programs or scripts on a Linux machine use this data to do some actual work.<ref>As you will see, it's relatively easy to create forms and accompanying programs for editing table content. It's definitely a lot less effort compared to achieve the same functionality in Linux with the [[wikipedia:curses (programming library)\|Curses Library]].</ref>		ODBC is also a nice way to utilize the AS/400 green screen interface basically as database file content editor, while programs or scripts on a Linux machine use this data to do some actual work.<ref>As you will see, it's relatively easy to create forms and accompanying programs for editing table content. It's definitely a lot less effort compared to achieve the same functionality in Linux with the [[wikipedia:curses (programming library)\|Curses Library]].</ref>

	It's also possible to use ''ftp'' to the AS/400 to get and put content. This is especially useful when handling ''save files'', which are the AS/400 equivalent of a ''tar file'' and must reside in the ''QSYS.LIB'' file system. Also FTP can be utilized for uploading binary stream files (graphics) which could be embedded in HTML files served by the ''IBM HTTP Server for AS/400''.<br />		It's also possible to use ''ftp'' to the AS/400 to get and put content. This is especially useful when handling ''save files'', which are the AS/400 equivalent of a ''tar file'' and must reside in the ''QSYS.LIB'' file system. Also FTP can be utilized for uploading binary stream files (graphics) which could be embedded in HTML files served by the ''[[IBM HTTP-Server for AS/400 Configuration\|IBM HTTP Server for AS/400]]''.<br />
	The FTP server on the AS/400 also allows the execution of commands (those to be typed in a green screen command line), as a possible replacement for the rexec-facility which is broken in most modern Linux distros.		The FTP server on the AS/400 also allows the execution of commands (those to be typed in a green screen command line), as a possible replacement for the rexec-facility which is broken or even non-existant in most modern Linux distros.

	Parts of the [[Filesystems and Files on the AS/400\|Filesystem]] can be exported via ''NFS'' to access data more directly. The NFS implementation on V4R5 is known to be painfully slow, though. Multiple seconds until a small directory list is displayed and transfer speeds in the low double-digit KBytes/s range are quite normal.		Parts of the [[Filesystems and Files on the AS/400\|Filesystem]] can be exported via ''NFS'' to access data more directly. The NFS implementation on V4R5 is known to be painfully slow, though. Multiple seconds until a small directory list is displayed and transfer speeds in the low double-digit KBytes/s range are quite normal.

← Older revision		Revision as of 23:59, 12 March 2020
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	Support for inter-vendor communications was provided with the licensed product ''TCP/IP Connectivity Utilities for AS/400'', [https://books.google.de/books?id=DR0EAAAAMBAJ&pg=PA1#v=onepage&q&f=false introduced by IBM in 1990].		Support for inter-vendor communications was provided with the licensed product ''TCP/IP Connectivity Utilities for AS/400'', [https://books.google.de/books?id=DR0EAAAAMBAJ&pg=PA1#v=onepage&q&f=false introduced by IBM in 1990].

	Today, IP on the AS/400 allows a multitude of communication tasks utilizing IP instead of SNA, ~~which~~ is way better understood by newbies in the IBM world of networking, then SNA.		Today, IP on the AS/400 allows a multitude of communication tasks utilizing IP instead of SNA, that is way better understood by newbies in the IBM world of networking, then SNA.

	Even though that IBM moved some IP processing into the corresponding I/O processor(s), IP transfers have a comparatively high impact on CPU load. Slower machines like the 9401-150 benefit greatly from utilizing SNA for bulk data transfers, since SNA hogs about one third of the CPU compared to IP.		Even though that IBM moved some IP processing into the corresponding I/O processor(s), IP transfers have a comparatively high impact on CPU load. Slower machines like the 9401-150 benefit greatly from utilizing SNA for bulk data transfers, since SNA hogs about one third of the CPU compared to IP.
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	* IPX.		* IPX.

	It is not clear if the ''NetServer'' feature<ref>Basically a piece of software ~~which~~ provides NetBIOS-Services: File Sharing and Printing. Kind of ''Samba from IBM''.</ref> also provides support for [[wikipedia:NetBIOS Frames protocol\|NetBIOS Frames protocol]], and ~~which~~ releases of OS/400 support this, if any.		It is not clear if the ''NetServer'' feature<ref>Basically a piece of software that provides NetBIOS-Services: File Sharing and Printing. Kind of ''Samba from IBM''.</ref> also provides support for [[wikipedia:NetBIOS Frames protocol\|NetBIOS Frames protocol]], and that releases of OS/400 support this, if any.

	Additionally with the so called ''AnyNet''-feature, OS/400 allows any of the above mentioned protocols be encapsulated in any other of the above. For that, it's possible to transfer SNA traffic across LAN segments and over WAN/VPNs built on IP. In fact, the AS/400 must (and thus can) act as an IP and IPX router between separate network segments to be able to do this encapsulation.<br />		Additionally with the so called ''AnyNet''-feature, OS/400 allows any of the above mentioned protocols be encapsulated in any other of the above. For that, it's possible to transfer SNA traffic across LAN segments and over WAN/VPNs built on IP. In fact, the AS/400 must (and thus can) act as an IP and IPX router between separate network segments to be able to do this encapsulation.<br />
	This facility has been superseded by the ''Enterprise Extender'' feature, ~~which~~ only permits the extension of SNA networks over IP networks. Routing and Encapsulation Support for other protocol combinations was shifted to special multiprotocol routers.		This facility has been superseded by the ''Enterprise Extender'' feature, that only permits the extension of SNA networks over IP networks. Routing and Encapsulation Support for other protocol combinations was shifted to special multiprotocol routers.

	Newer releases also support IPv6.		Newer releases also support IPv6.
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	== The AS/400 in a modern network ==		== The AS/400 in a modern network ==
	Today, the probably easiest solution is to connect the AS/400 machine to the ubiquitous Ethernet Network via a suitable Adapter Card. This card provides a ''line'' for the AS/400 ~~which~~ is to be configured with standard TCP/IP configuration parameters (Address, Netmask, Gateway). Additionally, a Domain Name System Server and Default DNS Domain can be supplied.		Today, the probably easiest solution is to connect the AS/400 machine to the ubiquitous Ethernet Network via a suitable Adapter Card. This card provides a ''line'' for the AS/400 that is to be configured with standard TCP/IP configuration parameters (Address, Netmask, Gateway). Additionally, a Domain Name System Server and Default DNS Domain can be supplied.

	The most important access method is ''tn5250'' to provide terminal access. This is basically a stock [[wikipedia:Telnet\|Telnet]] protocol, enriched with additional functionality for providing the necessary transport features for the 5250 data stream.<ref>IBM has published [https://tools.ietf.org/html/rfc1205 RFC1205] in 1991 and [https://tools.ietf.org/html/rfc2877 RFC2877] in 2000 ~~which~~ specify technical details.</ref>		The most important access method is ''tn5250'' to provide terminal access. This is basically a stock [[wikipedia:Telnet\|Telnet]] protocol, enriched with additional functionality for providing the necessary transport features for the 5250 data stream.<ref>IBM has published [https://tools.ietf.org/html/rfc1205 RFC1205] in 1991 and [https://tools.ietf.org/html/rfc2877 RFC2877] in 2000 that specify technical details.</ref>

	The AS/400 supports the configuration of Remote Printer Queues, being implicitly served by so called ''printer writer'' applications. These pick up spooled files, usually convert them to [[wikipedia:Printer Command Language\|PCL]] formatted ASCII data on the fly and transfer them to a [[wikipedia:Line Printer Daemon protocol\|LPR]] compatible printer, or host.<br />		The AS/400 supports the configuration of Remote Printer Queues, being implicitly served by so called ''printer writer'' applications. These pick up spooled files, usually convert them to [[wikipedia:Printer Command Language\|PCL]] formatted ASCII data on the fly and transfer them to a [[wikipedia:Line Printer Daemon protocol\|LPR]] compatible printer, or host.<br />
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	ODBC is also a nice way to utilize the AS/400 green screen interface basically as database file content editor, while programs or scripts on a Linux machine use this data to do some actual work.<ref>As you will see, it's relatively easy to create forms and accompanying programs for editing table content. It's definitely a lot less effort compared to achieve the same functionality in Linux with the [[wikipedia:curses (programming library)\|Curses Library]].</ref>		ODBC is also a nice way to utilize the AS/400 green screen interface basically as database file content editor, while programs or scripts on a Linux machine use this data to do some actual work.<ref>As you will see, it's relatively easy to create forms and accompanying programs for editing table content. It's definitely a lot less effort compared to achieve the same functionality in Linux with the [[wikipedia:curses (programming library)\|Curses Library]].</ref>

	It's also possible to use ''ftp'' to the AS/400 to get and put content. This is especially useful when handling ''save files'', ~~which~~ are the AS/400 equivalent of a ''tar file'' and must reside in the ''QSYS.LIB'' file system. Also FTP can be utilized for uploading binary stream files (graphics) ~~which~~ could be embedded in HTML files served by the ''[[IBM HTTP-Server for AS/400 Configuration\|IBM HTTP Server for AS/400]]''.<br />		It's also possible to use ''ftp'' to the AS/400 to get and put content. This is especially useful when handling ''save files'', that are the AS/400 equivalent of a ''tar file'' and must reside in the ''QSYS.LIB'' file system. Also FTP can be utilized for uploading binary stream files (graphics) that could be embedded in HTML files served by the ''[[IBM HTTP-Server for AS/400 Configuration\|IBM HTTP Server for AS/400]]''.<br />
	The FTP server on the AS/400 also allows the execution of commands (those to be typed in a green screen command line), as a possible replacement for the rexec-facility ~~which~~ is broken or even non-existant in most modern Linux distros.		The FTP server on the AS/400 also allows the execution of commands (those to be typed in a green screen command line), as a possible replacement for the rexec-facility that is broken or even non-existant in most modern Linux distros.

	Parts of the [[Filesystems and Files on the AS/400\|Filesystem]] can be exported via ''NFS'' to access data more directly. The NFS implementation on V4R5 is known to be painfully slow, though. Multiple seconds until a small directory list is displayed and transfer speeds in the low double-digit KBytes/s range are quite normal.		Parts of the [[Filesystems and Files on the AS/400\|Filesystem]] can be exported via ''NFS'' to access data more directly. The NFS implementation on V4R5 is known to be painfully slow, though. Multiple seconds until a small directory list is displayed and transfer speeds in the low double-digit KBytes/s range are quite normal.
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	=== Charset handling ===		=== Charset handling ===
	An obstacle to keep in mind is the the different character set of the AS/400 vs. todays common systems. The AS/400 utilizes the [[wikipedia:EBDIC\|EBCDIC]] character set ~~which~~ was invented by IBM in the punch card age, whereas common platforms utilize character sets based on [[wikipedia:ASCII\|ASCII]] and it's multibyte successors.		An obstacle to keep in mind is the the different character set of the AS/400 vs. todays common systems. The AS/400 utilizes the [[wikipedia:EBDIC\|EBCDIC]] character set that was invented by IBM in the punch card age, whereas common platforms utilize character sets based on [[wikipedia:ASCII\|ASCII]] and it's multibyte successors.

	Terminal access, FTP mode ASCII transfers<ref>This comes in handy when handling large amounts of source code.</ref> and ODBC do the necessary conversions invisibly in the background. Users have no need to care. Lpr does this when ''host transform'' is enabled in the printer queue configuration. NFS does no conversation and handles everything as binary data.		Terminal access, FTP mode ASCII transfers<ref>This comes in handy when handling large amounts of source code.</ref> and ODBC do the necessary conversions invisibly in the background. Users have no need to care. Lpr does this when ''host transform'' is enabled in the printer queue configuration. NFS does no conversation and handles everything as binary data.

	Modern common systems utilize UTF-8 as character set. Special chars will be encoded with two or more Bytes, while as ASCII utilizes only a single Byte.<br />		Modern common systems utilize UTF-8 as character set. Special chars will be encoded with two or more Bytes, while as ASCII utilizes only a single Byte.<br />
	Documentation for OS/400 mentions DBCS, Double-Byte Character Support, ~~which~~ is the IBM-Flavor of UTF-8. It seems that this support needs a special installation media set of OS/400.		Documentation for OS/400 mentions DBCS, Double-Byte Character Support, that is the IBM-Flavor of UTF-8. It seems that this support needs a special installation media set of OS/400.

	If the client for above mentioned services supports local conversion, there should be no problems for standard characters and most umlauts from Single- to Double-Byte and vice versa. This is the case with most tn5250 emulators.		If the client for above mentioned services supports local conversion, there should be no problems for standard characters and most umlauts from Single- to Double-Byte and vice versa. This is the case with most tn5250 emulators.