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- Newsgroups: comp.security.unix,comp.security.misc
- Subject: SSH (Secure Shell) FAQ - Frequently Asked Questions
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-
- Ssh (Secure Shell) FAQ - Frequently asked questions
- by Thomas K÷nig Thomas.Koenig@ciw.uni-karlsruhe.de
- $Date: 1996/03/27 14:17:53 $
-
- This document is a list of Frequently Asked Questions (plus hopefully
- correct answers) about the Secure Shell, ssh. IMPORTANT: There is a
- security bug in all versions of ssh before 1.2.12.92. Upgrade to a
- newer version is recommended.
-
-
- 1. Meta-questions
- 1.1. Where do I get this document?
- 1.2. Where do I send questions, corrections etc. about this document?
-
-
- 2. Ssh basics
- 2.1. What is ssh?
- 2.2. Why should I use it?
- 2.3. What kinds of attacks does ssh protect against?
- 2.4. What kind of attacks does ssh not protect against?
- 2.5. How does it work?
-
-
- 3. Obtaining and installing ssh
- 3.1. What is the latest version of ssh?
- 3.2. May I legally run ssh?
- 3.3. What about commercial use of ssh?
- 3.4. Where can I obtain ssh?
- 3.5. How do I install it?
- 3.6. Where do I get help?
- 3.7. Are there any versions for other operating systems than UNIX?
- 3.8. What about administration of ssh?
-
-
- 4. Ssh Applications
- 4.1. Can I run backups over ssh?
- 4.2. Should I turn encryption off, for performance reasons?
- 4.3. Can I use ssh to communicate across a firewall?
- 4.4. Can I distribute files with ssh, as with rdist?
- 4.5. Can I use ssh to securely connect two subnets across the
- Internet?
- 4.6. Can I use ssh to securely forward UDP-based services, such as NFS
- or NIS?
- 4.7. Can I forward SGI GL connections over ssh?
- 4.8. Can I use ssh to protect services like ftp or POP?
-
-
- 5. Problems
- 5.1. ssh otherhost xclient & does not work!
- 5.2. Ssh fails with "Resource temporarily unavailable" for Solaris 2.4
- 5.3. X11 forwarding does not work for an SCO binary with the iBCS2
- emulator under Linux.
- 5.4. Ssh is doing wrong things for multi-homed hosts!
- 5.5. Userid swapping is broken under AIX!
- 5.6. ssh-keygen dumps core on Alpha OSF!
- 5.7. ssh-keygen dumps core on Solaris or SunOS
- 5.8. On Linux, compilation aborts with some error message about
- libc.so.4
- 5.9. X authorization sometimes fails.
- 5.10. Ssh on Irix 5 tells me "You don't exist, go away!"
- 5.11. Ssh asks me for passwords despite .rhosts!
- 5.12. Why does ssh loop with "Secure connection refused'?
- 5.13. ssh-agent does not work with rxvt! rxvt closes all file
- descriptors when starting up, including the one used by
-
- 6. Miscellaneous
- 6.1. How widespread is use of ssh?
- 6.2. Credits
-
- 1. Meta-questions
-
- 1.1. Where do I get this document?
-
- The latest version of this document is available from http://www.uni-
- karlsruhe.de/~ig25/ssh-faq/. It will also be posted, on a regular
- basis, to the Usenet newsgroups comp.security.misc,
- comp.security.unix, comp.answers and news.answers. This version is
- PGP-signed, and will be available from
- ftp://rtfm.mit.edu/pub/usenet/news.answers/computer-security/ssh-faq
- and from http://www.uni-karlsruhe.de/~ig25/ssh-faq/ssh-faq.faq.
-
- The original SGML file is at http://www.uni-karlsruhe.de/~ig25/ssh-
- faq/ssh-faq.sgml.
-
- Also of interest is the ssh home page, at http://www.cs.hut.fi/ssh/.
-
- 1.2. Where do I send questions, corrections etc. about this document?
-
- Please send them to the maintainer, Thomas.Koenig@ciw.uni-karlsruhe.de
-
- 2. Ssh basics
-
-
- 2.1. What is ssh?
-
- To quote the README file:
-
- Ssh (Secure Shell) is a program to log into another computer over a
- network, to execute commands in a remote machine, and to move files
- from one machine to another. It provides strong authentication and
- secure communications over insecure channels. It is intended as a
- replacement for rlogin, rsh, and rcp.
-
- Additionally, ssh provides secure X connections and secure forwarding
- of arbitrary TCP connections.
-
- 2.2. Why should I use it?
-
- The traditional BSD 'r' - commmands (rsh, rlogin, rcp) are vulnerable
- to different kinds of attacks. Somebody who has root access to
- machines on the network, or physical access to the wire, can gain
- unauthorized access to systems in a variety of ways. It is also
- possible for such a person to log all the traffic to and from your
- system, including passwords (which ssh never sends in the clear).
-
- The X Window System also has a number of severe vulnerabilities. With
- ssh, you can create secure remote X sessions which are transparent to
- the user. As a side effect, using remote X clients with ssh is more
- convenient for users.
-
- Users can continue to use old .rhosts and /etc/hosts.equiv files;
- changing over to ssh is mostly transparent for them. If a remote site
- does not support ssh, a fallback mechanism to rsh is included.
-
- 2.3. What kinds of attacks does ssh protect against?
-
- Ssh protects against:
-
- o IP spoofing, where a remote host sends out packets which pretend to
- come from another, trusted host. Ssh even protects against a
- spoofer on the local network, who can pretend he is your router to
- the outside.
-
- o IP source routing, where a host can pretend that an IP packet comes
- from another, trusted host.
-
- o DNS spoofing, where an attacker forges name server records
-
- o Interception of cleartext passwords and other data by intermediate
- hosts.
-
- o Manipulation of data by people in control of intermediate hosts
-
- o Attacks based on listening to X authentication data and spoofed
- connection to the X11 server.
-
- In other words, ssh never trusts the net; somebody hostile who has
- taken over the network can only force ssh to disconnect, but cannot
- decrypted or play back the traffic, or hijack the connection.
-
- The above only holds if you actually use encryption. Ssh does have an
- option to use encryption of type "none" this is only for debugging
- purposes, and should not be used.
-
- 2.4. What kind of attacks does ssh not protect against?
-
- Ssh will not help you with anything that compromises your host's
- security in some other way. Once an attacker has gained root access to
- a machine, he can then subvert ssh, too.
-
- If somebody malevolent has access to your home directory, then
- security is nonexistent. This is very much the case if your home
- directory is exported via NFS.
-
- 2.5. How does it work?
-
- For more extensive information, please refer to the README and RFC
- files in the ssh directory. The proposed RFC is also available as an
- Internet Draft, as draft-ylonen-ssh-protocol-00.txt.
-
- All communications are encrypted using IDEA or one of several other
- ciphers (three-key triple-DES, DES, RC4-128, TSS). Encryption keys are
- exchanged using RSA, and data used in the key exchange is destroyed
- every hour (keys are not saved anywhere). Every host has an RSA key
- which is used to authenticate the host. Encryption is used to protect
- against IP-spoofing; public key authentication is used to protect
- against DNS and routing spoofing.
-
- RSA keys are also used to authenticate hosts.
-
- 3. Obtaining and installing ssh
-
-
- 3.1. What is the latest version of ssh?
-
- The latest officially released version is 1.2.0. The latest
- development version is 1.2.13.
-
- ssh-1.2.12.92 and later versions contain an important security fix.
- Using it instead of earlier versions is recommended. The fix here is
- intended to be temporary, and upgrading to the next release after that
- is highly recommended when it becomes available. The temporary fix
- has some drawbacks. For more information, read the ssh mailing list
- archive at
- http://www.cs.hut.fi/ssh/ssh-archive/.
-
-
- Ssh currently runs on UNIX or related systems, plus under OS/2. Ports
- have been successful to all "mainstream" UNIX systems. The current
- Windows version is believed to be unstable.
-
- At present, there are no known working versions for other operating
- systems (but see below).
-
- 3.2. May I legally run ssh?
-
- Ssh is free software, and can be freely used by anyone for any
- purpose.
-
- However, in some countries, particularly France, Russia, Iraq, and
- Pakistan, it may be illegal to use any encryption at all without a
- special permit.
-
- If you are in the United States, you should be aware that, while ssh
- was written outside the United States using information publicly
- available everywhere, the US Government may consider it a criminal
- offence to export this software from the US once it has been imported,
- including putting it on a ftp site. Contact the Office of Defence
- Trade Controls if you need more information.
-
- The algorithms RSA and IDEA, which are used by ssh, are claimed as
- patented in different countries, including the US. Linking against the
- RSAREF2 library, which is possible, may or may not make it legal to
- use ssh for non-commercial purposes in the US. You may need to obtain
- licenses for commercial use of IDEA; ssh can be configured to work
- without it. Ssh works perfectly fine without IDEA, however.
-
- For more detail, refer to the file COPYING in the ssh source
- distribution.
-
- For information on software patents in general, see the Leauge for
- Programming Freedom's homepage at http://lpf.org/.
-
-
- 3.3. What about commercial use of ssh?
-
- Ssh has been freely available in the Unix environment, and almost
- certainly will remain to be so in future.
-
- Tatu Yl÷nen, the original author of ssh, has started a company, SSH
- Communications Security Oy, that will provide commercial support and
- licenses for ssh. He is working on licensing the patents to be able
- to provide fully licensed commercial versions. The negotiations are
- still underway, and it will take a couple more weeks before it is
- known what the situation will really be.
-
- About commercial issues, it is best to contact him directly for now.
- I can best be reached by e-mail as
- ylo@cs.hut.fi, or by fax at +358-0-4354 3206.
-
- 3.4. Where can I obtain ssh?
-
- The central site for distributing ssh is ftp://ftp.cs.hut.fi/pub/ssh/.
-
- Official releases are PGP-signed, with the key ID
-
- DCB9AE01 1995/04/24 Ssh distribution key <ylo@cs.hut.fi>
- Key fingerprint = C8 90 C8 5A 08 F0 F5 FD 61 AF E6 FF CF D4 29 D9
-
-
- The latest development version is available from
- ftp://ftp.cs.hut.fi/pub/ssh/snapshots/.
-
- Ssh is also available via anonymous ftp from the following sites:
-
- Australia:
- ftp://coombs.anu.edu.au/pub/security/tools
-
- Chile:
- ftp://ftp.inf.utfsm.cl/pub/security/ssh
-
- Finland:
- ftp://ftp.funet.fi/pub/unix/security/login/ssh
-
- Germany:
- ftp://ftp.cert.dfn.de/pub/tools/net/ssh
-
- Hungary:
- ftp://ftp.kfki.hu/pub/packages/security/ssh
-
- Ireland:
- ftp://odyssey.ucc.ie/pub/ssh
-
- Poland:
- ftp://ftp.agh.edu.pl/pub/security/ssh
-
- Portugal:
- ftp://ftp.ci.uminho.pt/pub/security/ssh
-
- Russia:
- ftp://ftp.kiae.su/unix/crypto
-
- Slovenia:
- ftp://ftp.arnes.si/security/ssh
-
- United Kingdom:
- ftp://ftp.exweb.com/pub/security/ssh
-
- United States:
- ftp://ftp.net.ohio-state.edu/pub/security/ssh
-
- United States:
- ftp://ftp.gw.com/pub/unix/ssh
-
- Some mirrors may not have the most recent snapshots available.
-
- 3.5. How do I install it?
-
- Get the file from a site near you, then unpack it with
-
- gzip -c -d ssh-1.2.13.tar.gz | tar xvf -
-
-
- then change into the directory ssh-1.2.13, read the file INSTALL, and
- follow the directions in it.
-
- 3.6. Where do I get help?
-
- First of all, read the documentation, this document :-) and the ssh
- home page, at http://www.cs.hut.fi/ssh/.
-
- If this doesn't help, you can send mail to the mailing list for ssh
- users at ssh@clinet.fi. To subscribe, send mail to
- majordomo@clinet.fi with
-
- subscribe ssh
-
-
- in the body of the message.
-
- Before subscribing, you might like to take a look at the archives of
- the mailing list, at http://www.cs.hut.fi/ssh/ssh-archive.
-
- 3.7. Are there any versions for other operating systems than UNIX?
-
- Heikki Suonsivu (hsu@clinet.fi) and Michael Henits (moi@dio.com) each
- offered a US$ 100 reward for the first stable, freely redistributable
- version for either Windows or MacOS.
-
- There is a preliminary version for Windows by Cedomir.Igaly@srce.hr,
- available from http://public.srce.hr/~cigaly/ssh/; you might want to
- test this. A mirror is avialable from
- ftp://ftp.cs.hut.fi/pub/ssh/windows/cigaly/; the filename is
- ssh-1-2-.zip.
-
- Tatu Yl÷nen, the original author of ssh, is currently working on a
- Windows version.
-
- Bernt.Budde@udac.uu.se is working on a Mac port.
-
- A port to VMS, by Mark Martinec (Mark.Martinec@nsc.ijs.si), is being
- worked on.
-
- A port to OS/2 can be obtained from ftp://ftp.cs.hut.fi/pub/ssh/os2/.
- The current maintainer, Robert Muchsel (rmuchsel@iiic.ethz.ch) does
- not have much time to continue supporting it; if you're interested in
- doing so, please drop him a line.
-
- There is a special mailing list for the OS/2 version of ssh. To
- subscribe, send mail to majordomo@clinet.fi with
-
- subscribe ssh-os2
-
-
- in the body of the message.
-
- 3.8. What about administration of ssh?
-
- The central problem of administering ssh is the management of host
- keys. You can collect them automatically each night using either
- make-ssh-known-hosts.pl (distributed with the ssh source distribution)
- or with the much faster ssh-keyscan, from
- ftp://cag.lcs.mit.edu/pub/dm/ (also available from
- ftp://ftp.cs.hut.fi/ssh/contrib/).
-
- Thomas K÷nig has written a script to process output from one of these
- utilities, check for new keys, warn about hosts which have changed
- their keys (which could be an indication of a man in the middle
- attack) and generate a complete new file. This script is available
- from http://www.uni-karlsruhe.de/~ig25/ssh-faq/comp-host-list.
-
- With these utilities, you can write scripts to verify public keys on a
- regular basis. When new machines are running ssh or people have
- changed public keys, you may want to contact the people in question
- directly, to make sure there were no man in the middle attacks (to
- which these utilities are vulnerable).
-
- A fingerprint scheme (equivalent to PGP fingerprints) has been
- proposed to make this easier; it will probably be implemented in the
- next release.
-
-
- 4. Ssh Applications
-
-
- 4.1. Can I run backups over ssh?
-
- Yes. Since ssh is a drop-in replacement for rsh, backup scripts should
- continue to work. If you use rdist, see below.
-
- 4.2. Should I turn encryption off, for performance reasons?
-
- No; you should keep it turned on, for security reasons.
-
- Today's CPUs are fast enough that performance losses (if any) only are
- noticable for local Ethernet speeds, or faster.
-
- You might want to specify RC4 encryption instead of the default, IDEA,
- with -c rc4, for faster operation.
-
- Following are some measurements where the different encryption methods
- were applied between a P5/90 and a 486/100, both running Linux, for
- copying files with scp across a lightly loaded Ethernet.
-
- The model chosen was t=a+x/b; a is the startup time in seconds, and b
- the sustainable transfer rate in kB/s. Also given are the 68.3%
- confidence intervals for the data, as determined by the Levenberg-
- Marquardt algorithm as implemented a pre-3.6 version of gnuplot.
-
-
- Encryption a[s] da[s] b[kB/s] db[kB/s]
- none 2.37 0.37 386.1 5.8
- rc4 1.96 0.27 318.2 2.9
- tss 2.33 0.37 298.5 3.5
- des 2.07 0.19 218.8 1.0
- idea 2.25 0.45 169.6 1.3
- 3des 1.92 0.11 118.2 0.2
-
-
- Across a heavily loaded Ethernet, rc4 encryption together with
- compression may actually be faster than using rcp.
-
- If you don't encrypt your sessions, you are vulnerable to all the
- attacks which are open on the "r" suite of utilities, and you might as
- well not use ssh.
-
- 4.3. Can I use ssh to communicate across a firewall?
-
- Yes; you can use TCP forwarding for that, by using its secure TCP
- forwarding features.
-
- 4.4. Can I distribute files with ssh, as with rdist?
-
- Stock rdist 6.1.0 does not work together with ssh, due to bugs in it.
- The 6.1.1 versions of rdist and later versions are believed to work.
-
- If you use rdist, don't forget to compile the path to ssh into it.
- Alternatively, you may specify the -P option so rdist uses ssh, and
- not rsh.
-
- 4.5. Can I use ssh to securely connect two subnets across the Inter¡
- net?
-
- This has been discussed on the ssh mailing list. A proposed solution
- was to run ppp with TCP forwarding; however, this has not been
- implemented yet.
-
- Another solution, proposed and executed by anthony.baxter@aaii.oz.au,
- is to use tunnel devices.
-
- If you have details of anything that works, please forward them to the
- ssh mailing list.
-
- 4.6. Can I use ssh to securely forward UDP-based services, such as
- NFS or NIS?
-
- There is a general working solution for RPC-based services, such as
- NIS. You can download it from ftp://ftp.tu-
- chemnitz.de/pub/Local/informatik/sec_rpc/. NIS, in particular, is
- working.
-
- In principle, this could also be adapted for NFS; this has not been
- done yet.
-
- Services which are based purely on UDP, such as DNS, have not been
- secured with ssh yet, although it is possible in principle.
-
- 4.7. Can I forward SGI GL connections over ssh?
-
- It is not likely that this will be implemented. GL uses a totally
- different protocol from X, and at least gld would have to be replaced.
-
- OpenGL, when run as an X server extension, should pose no problem.
-
- 4.8. Can I use ssh to protect services like ftp or POP?
-
- If you want to avoid sending ftp passwords in cleartext over the net,
- you can use ssh to encrypt your command channel. Suppose you are on a
- host called myhost and want to initiate a ftp connection to ftphost.
- On mymachine, you do
-
- mymachine$ ssh -L 1234:ftphost.do.main:21 ftphost
-
-
- This logs you on to ftphost and also forwards connections to 1234 on
- mymachine to ftphost.
-
- Then, in another window, you to
-
- mymachine$ ftp mymachine 1234
- 220 ftphost FTP server (Foonix 08/15) ready.
- Name: (mymachine:yourname):
- 331 Password required for yourname
- Password:
- 230 User yourname logged in.
-
-
- For POP, Stephane Bortzmeyer (bortzmeyer@pasteur.fr) has written a
- script which protects the mail transfer and passwords ussing ssh. It
- requires no modification to existing POP servers or clients, and is
- available from ftp://ftp.pasteur.fr/pub/Network/gwpop/.
-
- Other services could be secured by similar means.
-
- 5. Problems
-
- If you don't find your problem listed below, please submit a bug
- report to ssh-bugs@clinet.fi giving full details of
-
- o Version number of ssh and (if different) sshd
-
-
- o What you expected ssh to do
-
- o What ssh did instead (including all error messages)
-
- o The system you use (for example, the output of uname -a), and the
- output of config.guess.
-
- o The compiler you used, plus any compilation flags
-
- o The output of ssh -v
-
- o The output of the sshd daemon when run in debug mode, as sshd -d
-
- Please try the latest snapshot from
- ftp://ftp.cs.hut.fi/pub/ssh/snapshots/ before reporting any bug.
-
- 5.1. ssh otherhost xclient & does not work!
-
- No, it doesn't. Use "ssh -f otherhost xclient" instead, or "ssh -n
- otherhost xclient &" if you want a script to be compatible with rsh.
-
- 5.2. Ssh fails with "Resource temporarily unavailable" for Solaris
- 2.4
-
- This is a kernel bug in Solaris. Get the patch 101945-34 to fix it.
-
- 5.3. X11 forwarding does not work for an SCO binary with the iBCS2
- emulator under Linux.
-
- You need to set the hostname to the fully qualified domain name for
- this to work. Some Linux distributions set the hostname to the first
- part of the FQDN only.
-
- 5.4. Ssh is doing wrong things for multi-homed hosts!
-
- Check whether gethostbyname() really returns the complete lists of
- possible IP addresses (you might, for example, have your system
- configured to search /etc/hosts first, which might contain only one of
- the IP addresses).
-
- 5.5. Userid swapping is broken under AIX!
-
- This is a bug in AIX 3.2.5, reported as APAR IX38941, and fixed by
- patches U435001, U427862, U426915, and a few others. Contact your IBM
- representative for details.
-
- 5.6. ssh-keygen dumps core on Alpha OSF!
-
- For Alpha OSF/1 1.3.2, this is due to a bug in the vendor-supplied
- compiler with maximum optimization.
-
- Turn off all optimization for ssh-keygen, or use gcc.
-
- 5.7. ssh-keygen dumps core on Solaris or SunOS
-
- This is a bug in gcc 2.7.0, which causes it to generated incorrect
- code without optimization. Supply the "-O" or "-O -g" options to gcc
- when compiling. Alternatively, upgrade to gcc 2.7.2.
-
- 5.8. On Linux, compilation aborts with some error message about
- libc.so.4
-
- This is an incorrectly configured Linux system; do a "cd /usr/lib; ln
- -s libc.sa libg.sa" as root to remedy this.
-
-
- 5.9. X authorization sometimes fails.
-
- This is believed to be a bug in HP-UX 9 xauth, SR 5003209619. Patch
- PHSS_5568 is believed to fix this problem.
-
- If this occurs for any other platform, please mail details to
- ssh-bugs@clinet.fi.
-
- 5.10. Ssh on Irix 5 tells me "You don't exist, go away!"
-
- As of 1.2.12, you need to remove -lnsl in the Makefile. A later
- version of ssh might fix this.
-
- 5.11. Ssh asks me for passwords despite .rhosts!
-
- There are several possibilities why this could be the case; common
- ones include
-
- o The client host key is not stored in the known_hosts file. Note
- that this has to be the canonical (usually, the fully qualified)
- domain name.
-
- o The host does not have a reverse mapping in the name servers. Note
- that ssh requires that it has both a reverse mapping, and a forward
- mapping that contains the original IP address.
-
- o A multi-homed host does not have all of its IP addresses listed in
- the DNS entry. Note that versions prior to 1.2.12 have bugs in
- handling multi-homed hosts.
-
- o User's home directory or ~/.rhosts is world or group-writable (see
- StrictModes server configuration option).
-
- o On some machines, if the home directory is on an NFS volume,
- ~/.rhosts and your home directory may need to be world-readable.
-
- o The root account has to use ~/.rhosts or ~/.shosts;
- /etc/shosts.equiv and /etc/hosts.equiv are disregarded for root.
-
- o Confusion between RhostsRSAAuthentication and RSAAuthentication.
-
- RhostsRSAAuthentication is a functional replacement for the 'r'
- utilities; this requires the ssh program to be setuid root, a
- secret key in /etc/host_key file on the client, a corresponding
- public key entry in /etc/ssh_known_hosts, plus entries in
- ~/.[sr]hosts or /etc/[s]hosts.equiv.
-
- RSAAuthentication is done on a per-user basis and requires a
- ~/.ssh/identity file on the client side (to be generated with ssh-
- keygen), plus a matching ~/.ssh/authorized_keys on the server side.
-
- 5.12. Why does ssh loop with "Secure connection refused'?
-
- This is a configuration problem.
-
- Ssh attempts to fall back to the "r" commands when it cannot connect
- to an ssh daemon on the remote host. It does this by execing your old
- rsh to use the old protocol.
-
- There are two possibilities why this could be:
-
- o You probably have installed ssh as rsh, and forgotten to give the
- --with-rsh=PATH option to configure the second time. When ssh is
- looking for rsh, it keeps executing itself (or an older version of
- itself). To solve this, recompile ssh with the correct place for
- rsh.
- o You moved the old rsh and rlogin into a different directory and
- correctly are calling the old rsh. The old rsh has a hard-coded
- path to the old rlogin program, so you wind up execing the old rsh
- which in turn execs the new replacement (ssh)rlogin.
-
- In that case, you might want to move the old rsh and rlogin
- binaries into /usr/old, patch the old rsh binary by running the
- Perl script
-
- perl -pi.orig -e 's+/usr/(bin|ucb)/rlogin+/usr/old/rlogin+g ;' /usr/old/rsh
-
-
- which will generate a patched version of rsh and save the old one in
- /usr/old/rsh.orig.
-
- Reconfigure ssh with --with-rsh=/usr/old/rsh.
-
- 5.13. rxvt closes all file descriptors when starting up, including
- the one used by ssh-agent. Use xterm, or look at the mailing list
- archives at http://www.cs.hut.fi/ssh/ssh-archive/ for Timo Rinne's
- rxvt patch. ssh-agent does not work with rxvt!
-
- 6. Miscellaneous
-
-
- 6.1. How widespread is use of ssh?
-
- As with every piece of freely available software, this is difficult to
- find out. The best current estimates are that at least 1000
- insitutions in 40 countries use it. This estimate is based on
-
- o The number of people on the ssh mailing list, around 600, from 40
- different countries and several hundred domains
-
- o Each week, the ssh home pages are accessed from roughly 5000
- different machines, many of them web caches; also, these machines
- often are different from week to week.
-
-
- 6.2. Credits
-
- Most of the credit, of course, goes to Tatu Yl÷nen for writing ssh and
- making it available to the public. I have also used parts of his text
- from the documentation accompanying the ssh source distribution.
- Thanks also for his corrections for this FAQ.
-
- Also of invaluable help were corrections and additions from members of
- the ssh mailing list and the Usenet newsgroups, by Mark Martinec,
- Pedro Melo, Michael Soukas, Adrian Colley, Kenneth J. Hendrickson,
- Adam Hammer, Olaf Titz, David Mazieres and Wayne Schroeder.
-
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