1

I use PuTTY on Windows to establish an SSH connection to a remote server and am trying to set up google-authenticator two-factor authentication, so I installed it on the remote server and run it to set up the QR code with an app on my phone, however the URL, which should appear right above the QR code, and QR code are clipped, rendering it invalid.

Why does this happen when using PuTTY?

  • When I try scrolling up in PuTTY, I can't see the whole QR code: Screenshot1

  • Not reproducible within a Linux terminal: Screenshot2

Update

I took a look at the Putty Settings: Terminal and Window sections but I'm not sure what I'm supposed to be seeing there. I have 500 Lines of scrollback. I would have thought that would let me scroll up the screen to see all the QR code.

As requested here is the registry key for the OSMC profile I was using to make that ssh connection in Putty. I redacted anything private.

Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\SimonTatham\PuTTY\Sessions\OSMC]
"Present"=dword:00000001
"HostName"="192.168.1.3"
"LogFileName"="putty.log"
"LogType"=dword:00000000
"LogFileClash"=dword:ffffffff
"LogFlush"=dword:00000001
"SSHLogOmitPasswords"=dword:00000001
"SSHLogOmitData"=dword:00000000
"Protocol"="ssh"
"PortNumber"=dword:00000016
"CloseOnExit"=dword:00000001
"WarnOnClose"=dword:00000001
"PingInterval"=dword:00000000
"PingIntervalSecs"=dword:00000000
"TCPNoDelay"=dword:00000001
"TCPKeepalives"=dword:00000000
"TerminalType"="xterm"
"TerminalSpeed"="38400,38400"
"TerminalModes"="CS7=A,CS8=A,DISCARD=A,DSUSP=A,ECHO=A,ECHOCTL=A,ECHOE=A,ECHOK=A,ECHOKE=A,ECHONL=A,EOF=A,EOL=A,EOL2=A,ERASE=A,FLUSH=A,ICANON=A,ICRNL=A,IEXTEN=A,IGNCR=A,IGNPAR=A,IMAXBEL=A,INLCR=A,INPCK=A,INTR=A,ISIG=A,ISTRIP=A,IUCLC=A,IUTF8=A,IXANY=A,IXOFF=A,IXON=A,KILL=A,LNEXT=A,NOFLSH=A,OCRNL=A,OLCUC=A,ONLCR=A,ONLRET=A,ONOCR=A,OPOST=A,PARENB=A,PARMRK=A,PARODD=A,PENDIN=A,QUIT=A,REPRINT=A,START=A,STATUS=A,STOP=A,SUSP=A,SWTCH=A,TOSTOP=A,WERASE=A,XCASE=A"
"AddressFamily"=dword:00000000
"ProxyExcludeList"=""
"ProxyDNS"=dword:00000001
"ProxyLocalhost"=dword:00000000
"ProxyMethod"=dword:00000000
"ProxyHost"="proxy"
"ProxyPort"=dword:00000050
"ProxyUsername"=""
"ProxyPassword"=""
"ProxyTelnetCommand"="connect %host %port\\n"
"Environment"=""
"UserName"="osmc"
"UserNameFromEnvironment"=dword:00000000
"LocalUserName"=""
"NoPTY"=dword:00000000
"Compression"=dword:00000000
"TryAgent"=dword:00000001
"AgentFwd"=dword:00000000
"GssapiFwd"=dword:00000000
"ChangeUsername"=dword:00000000
"Cipher"="aes,chacha20,blowfish,3des,WARN,arcfour,des"
"KEX"="ecdh,dh-gex-sha1,dh-group14-sha1,rsa,WARN,dh-group1-sha1"
"RekeyTime"=dword:0000003c
"RekeyBytes"="1G"
"SshNoAuth"=dword:00000000
"SshBanner"=dword:00000001
"AuthTIS"=dword:00000000
"AuthKI"=dword:00000001
"AuthGSSAPI"=dword:00000001
"GSSLibs"="gssapi32,sspi,custom"
"GSSCustom"=""
"SshNoShell"=dword:00000000
"SshProt"=dword:00000003
"LogHost"=""
"SSH2DES"=dword:00000000
"PublicKeyFile"="anonymized"
"RemoteCommand"=""
"RFCEnviron"=dword:00000000
"PassiveTelnet"=dword:00000000
"BackspaceIsDelete"=dword:00000001
"RXVTHomeEnd"=dword:00000000
"LinuxFunctionKeys"=dword:00000000
"NoApplicationKeys"=dword:00000000
"NoApplicationCursors"=dword:00000000
"NoMouseReporting"=dword:00000000
"NoRemoteResize"=dword:00000000
"NoAltScreen"=dword:00000000
"NoRemoteWinTitle"=dword:00000000
"RemoteQTitleAction"=dword:00000001
"NoDBackspace"=dword:00000000
"NoRemoteCharset"=dword:00000000
"ApplicationCursorKeys"=dword:00000000
"ApplicationKeypad"=dword:00000000
"NetHackKeypad"=dword:00000000
"AltF4"=dword:00000001
"AltSpace"=dword:00000000
"AltOnly"=dword:00000000
"ComposeKey"=dword:00000000
"CtrlAltKeys"=dword:00000001
"TelnetKey"=dword:00000000
"TelnetRet"=dword:00000001
"LocalEcho"=dword:00000002
"LocalEdit"=dword:00000002
"Answerback"="PuTTY"
"AlwaysOnTop"=dword:00000000
"FullScreenOnAltEnter"=dword:00000000
"HideMousePtr"=dword:00000000
"SunkenEdge"=dword:00000000
"WindowBorder"=dword:00000001
"CurType"=dword:00000000
"BlinkCur"=dword:00000000
"Beep"=dword:00000000
"BeepInd"=dword:00000000
"BellWaveFile"=""
"BellOverload"=dword:00000001
"BellOverloadN"=dword:00000005
"BellOverloadT"=dword:000007d0
"BellOverloadS"=dword:00001388
"ScrollbackLines"=dword:000001f4
"DECOriginMode"=dword:00000000
"AutoWrapMode"=dword:00000001
"LFImpliesCR"=dword:00000000
"CRImpliesLF"=dword:00000000
"DisableArabicShaping"=dword:00000000
"DisableBidi"=dword:00000000
"WinNameAlways"=dword:00000001
"WinTitle"=""
"TermWidth"=dword:00000078
"TermHeight"=dword:00000020
"Font"="Courier New"
"FontIsBold"=dword:00000000
"FontCharSet"=dword:00000000
"FontHeight"=dword:0000000c
"FontQuality"=dword:00000000
"FontVTMode"=dword:00000004
"UseSystemColours"=dword:00000000
"TryPalette"=dword:00000000
"ANSIColour"=dword:00000001
"Xterm256Colour"=dword:00000001
"BoldAsColour"=dword:00000001
"Colour0"="187,187,187"
"Colour1"="255,255,255"
"Colour2"="0,0,0"
"Colour3"="85,85,85"
"Colour4"="0,0,0"
"Colour5"="0,255,0"
"Colour6"="0,0,0"
"Colour7"="85,85,85"
"Colour8"="187,0,0"
"Colour9"="255,85,85"
"Colour10"="0,187,0"
"Colour11"="85,255,85"
"Colour12"="187,187,0"
"Colour13"="255,255,85"
"Colour14"="0,0,187"
"Colour15"="85,85,255"
"Colour16"="187,0,187"
"Colour17"="255,85,255"
"Colour18"="0,187,187"
"Colour19"="85,255,255"
"Colour20"="187,187,187"
"Colour21"="255,255,255"
"RawCNP"=dword:00000000
"PasteRTF"=dword:00000000
"MouseIsXterm"=dword:00000000
"RectSelect"=dword:00000000
"MouseOverride"=dword:00000001
"Wordness0"="0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0"
"Wordness32"="0,1,2,1,1,1,1,1,1,1,1,1,1,2,2,2,2,2,2,2,2,2,2,2,2,2,1,1,1,1,1,1"
"Wordness64"="1,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,1,1,1,1,2"
"Wordness96"="1,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,1,1,1,1,1"
"Wordness128"="1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1"
"Wordness160"="1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1"
"Wordness192"="2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,1,2,2,2,2,2,2,2,2"
"Wordness224"="2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,1,2,2,2,2,2,2,2,2"
"LineCodePage"="UTF-8"
"CJKAmbigWide"=dword:00000000
"UTF8Override"=dword:00000001
"Printer"=""
"CapsLockCyr"=dword:00000000
"ScrollBar"=dword:00000001
"ScrollBarFullScreen"=dword:00000000
"ScrollOnKey"=dword:00000000
"ScrollOnDisp"=dword:00000001
"EraseToScrollback"=dword:00000001
"LockSize"=dword:00000000
"BCE"=dword:00000001
"BlinkText"=dword:00000000
"X11Forward"=dword:00000000
"X11Display"=""
"X11AuthType"=dword:00000001
"X11AuthFile"=""
"LocalPortAcceptAll"=dword:00000000
"RemotePortAcceptAll"=dword:00000000
"PortForwardings"=""
"BugIgnore1"=dword:00000000
"BugPlainPW1"=dword:00000000
"BugRSA1"=dword:00000000
"BugIgnore2"=dword:00000000
"BugHMAC2"=dword:00000000
"BugDeriveKey2"=dword:00000000
"BugRSAPad2"=dword:00000000
"BugPKSessID2"=dword:00000000
"BugRekey2"=dword:00000000
"BugMaxPkt2"=dword:00000000
"StampUtmp"=dword:00000001
"LoginShell"=dword:00000001
"ScrollbarOnLeft"=dword:00000000
"BoldFont"=""
"BoldFontIsBold"=dword:00000001
"BoldFontCharSet"=dword:02aa64a6
"BoldFontHeight"=dword:77704dcd
"WideFont"=""
"WideFontIsBold"=dword:00000001
"WideFontCharSet"=dword:0018ff78
"WideFontHeight"=dword:776c3436
"WideBoldFont"=""
"WideBoldFontIsBold"=dword:00000001
"WideBoldFontCharSet"=dword:0018faf0
"WideBoldFontHeight"=dword:01006446
"ShadowBold"=dword:00000000
"ShadowBoldOffset"=dword:00000001
"SerialLine"="COM1"
"SerialSpeed"=dword:00002580
"SerialDataBits"=dword:00000008
"SerialStopHalfbits"=dword:00000002
"SerialParity"=dword:00000000
"SerialFlowControl"=dword:00000001
"WindowClass"=""
"LogHeader"=dword:00000001
"ProxyLogToTerm"=dword:00000001
"HostKey"="ed25519,ecdsa,rsa,dsa,WARN"
"GssapiRekey"=dword:00000002
"AuthGSSAPIKEX"=dword:00000001
"NoRemoteClearScroll"=dword:00000000
"TrueColour"=dword:00000001
"UTF8linedraw"=dword:00000000
"PasteControls"=dword:00000000
"MouseAutocopy"=dword:00000001
"MousePaste"="explicit"
"CtrlShiftIns"="explicit"
"CtrlShiftCV"="none"
"BugOldGex2"=dword:00000000
"BugWinadj"=dword:00000000
"BugChanReq"=dword:00000000
"ConnectionSharing"=dword:00000000
"ConnectionSharingUpstream"=dword:00000001
"ConnectionSharingDownstream"=dword:00000001
"SSHManualHostKeys"=""

Thanks

8
  • 1
    This is likely due to the SettingsTerminal and/or SettingsWindows configuration. If you're unable to determine which setting, please add the output of the following registry key, within a code box, to your question: HKCU\SOFTWARE\SimonTatham\PuTTY\Sessions\<session name> (where <session name> is the name of the saved profile - if not using a saved profile: Default%20Settings. Please anonymize the following DWORDs and Strings before posting: HostName, PortForwardings, PublicKeyFile, and ProxyTelnetCommand)
    – JW0914
    Nov 1 '20 at 13:06
  • I updated my question. Any help much appreciated. Cheers. Nov 2 '20 at 2:51
  • 1
    If you used an OpenSSH Client instance instead of putty does it behave as you might expect?
    – Ramhound
    Nov 2 '20 at 6:04
  • 1
    @FlexMcMurphy Try increasing scrollback (I use 100000) and changing ConnectionDataTerminal-type String to xterm-256color. If neither of those fix it, you may want to submit a bug report, and you may also want to check the termcap config on the remote server if it's using one (e.g. /usr/share/misc/termcap, with the location varying by OS)
    – JW0914
    Nov 2 '20 at 11:48
  • @Ramhound I don't understand what you mean by "an OpenSSH Client instance"? I tried from a terminal on Raspbian OS and it worked. When it doesn't work in Putty I first ssh in to a Raspberry Pi then from there I use mosh to ssh to the remote server and run google-authenticate from the remote server. I guess the mosh command creates an OpenSSH Client instance? Nov 2 '20 at 11:49
1

In PuTTY's settings, increase the scrollback and change terminal-type to xterm-256color:

  1. WindowLines of scrollback: 100000
  2. Connection → Data → Terminal-type String: xterm-256color

If neither of these fix the issue, please check the terminfo/termcap config on the remote server for the settings configured for xterm, xterm-256color, or other terminal-type string being used.

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