Hi, it really depends on your name resolution. If you access hostx.my.ipv6.domain and this name resolves to an ipv6 address, this will be used. Also, if you only access the short name hostx and have my.ipv6.domain in the list of domains in /etc/resolv.conf's search line before my.ipv4.domain it will be preferred.
Uli On Tue, Jan 20, 2026 at 9:48 AM Athanasios Silis <[email protected]> wrote: > > Ah this is a unix command. yeah it exists in slackware too. > Didn't think of this. Still is there a way (that you know of) to prioritize > ipv4 over ipv6 ? > for example I read that /etc/hosts file can lead to ipv6 resolution with > priority if the ::1 entry is above the 127.0.0.1 one. But this is not the > case in my case. > > Alternatively, is it possible to tell the X server to prefer ipv4 over ipv6 ? > > > On Tue, Jan 20, 2026 at 10:43 AM Ulrich Sibiller <[email protected]> > wrote: >> >> Hi, >> >> well, of course IPv4 should suffice. Maybe you should check if your >> name resolution yields IPv6 addresses. No idea how slackware handles >> this but there should be a straightforward way to disable IPv6. Using >> firewall rules seems wrong to me. >> >> In RedHat you can do this using sysctl and set >> "net.ipv6.conf.all.disable_ipv6 = 1". >> >> Uli >> >> On Mon, Jan 19, 2026 at 11:23 PM Athanasios Silis >> <[email protected]> wrote: >> > >> > Ok I have figured it out, but I don't think it should be like that. >> > >> > So I have completely disabled ipv6 on that laptop (policy is DROP for all >> > chains INPUT, OUTPUT and FORWARD). No it did not even accept localhost >> > connections in ipv6. >> > Once I changed the firewall to accept local ipv6 connections (accept from >> > localhost only and accept OUTgoing packets in output chain) things started >> > working again. >> > >> > The question is. Shouldn't ipv4 suffice for all this to work ? >> > >> > This question has no practical value but I would very much like to >> > understand why does ipv6 must be allowed internally. >> > >> > Thank you for your help Ulrich! >> > >> > >> > On Mon, Jan 19, 2026 at 11:03 PM Athanasios Silis >> > <[email protected]> wrote: >> >> >> >> hi Ulrich, >> >> thank you for the quick response. >> >> Definitely X11 systems across all the systems I admin - no wayland. >> >> >> >> The quick test does indeed create an nxagent window . It does delay >> >> unreasonably though for about 10seconds at some point. >> >> Eventually it does continue and I do see the black/empty window >> >> eventually. You'll notice that the nxagent on the server side is >> >> (thankfully) Version 3.5.99.26. >> >> Please note: the x2goserver resides on a slackware64-current system. But >> >> I have another reference system (slackware64-15.0) with the exact same >> >> x2goserver version. >> >> The reference version works fine and running the same test there works >> >> fine too, but it does not "halt" at the moment when the problematic halts >> >> for about 10 seconds. >> >> >> >> OK so the log in the problematic system is as follows: >> >> >> >> nass@whitestar$ ssh blackstar -X >> >> Last login: Mon Jan 19 22:37:27 2026 from 192.168.112.145 >> >> Linux 6.12.63. >> >> >> >> nass@blackstar:~$ nxagent :55 >> >> >> >> NXAGENT - Version 3.5.99.26 >> >> >> >> Copyright (c) 2001, 2011 NoMachine (http://www.nomachine.com) >> >> Copyright (c) 2008-2014 Oleksandr Shneyder <[email protected]> >> >> Copyright (c) 2011-2016 Mike Gabriel <[email protected]> >> >> Copyright (c) 2014-2016 Ulrich Sibiller <[email protected]> >> >> Copyright (c) 2014-2016 Mihai Moldovan <[email protected]> >> >> Copyright (c) 2015-2016 Qindel Group (http://www.qindel.com) >> >> See https://github.com/ArcticaProject/nx-libs for more information. >> >> >> >> Info: Agent running with pid '17964'. >> >> Session: Starting session at 'Mon Jan 19 22:49:53 2026'. >> >> >> >> [It seemingly blocks for about 10seconds here. Then it continues...] >> >> >> >> Info: Using alpha channel in render extension. >> >> Info: Not using local device configuration changes. >> >> Warning: Cannot read keystroke file >> >> '/home/nass/.nx/config/keystrokes.cfg'. >> >> Info: using keystrokes file '/etc/nxagent/keystrokes.cfg' >> >> Currently known keystrokes: >> >> close_session : Ctrl+Alt+t >> >> switch_all_screens : Ctrl+Alt+f >> >> fullscreen : Ctrl+Shift+Alt+f >> >> minimize : Ctrl+Alt+m >> >> defer : Ctrl+Alt+e >> >> force_synchronization : Ctrl+Alt+j >> >> resize : Ctrl+Alt+r >> >> viewport_move_left : Ctrl+Shift+Alt+Left >> >> viewport_move_left : Ctrl+Shift+Alt+KP_Left >> >> viewport_move_up : Ctrl+Shift+Alt+Up >> >> viewport_move_up : Ctrl+Shift+Alt+KP_Up >> >> viewport_move_right : Ctrl+Shift+Alt+Right >> >> viewport_move_right : Ctrl+Shift+Alt+KP_Right >> >> viewport_move_down : Ctrl+Shift+Alt+Down >> >> viewport_move_down : Ctrl+Shift+Alt+KP_Down >> >> viewport_scroll_left : Ctrl+Alt+Left >> >> viewport_scroll_left : Ctrl+Alt+KP_Left >> >> viewport_scroll_up : Ctrl+Alt+Up >> >> viewport_scroll_up : Ctrl+Alt+KP_Up >> >> viewport_scroll_right : Ctrl+Alt+Right >> >> viewport_scroll_right : Ctrl+Alt+KP_Right >> >> viewport_scroll_down : Ctrl+Alt+Down >> >> viewport_scroll_down : Ctrl+Alt+KP_Down >> >> reread_keystrokes : Ctrl+Alt+k >> >> autograb : Ctrl+Alt+g >> >> dump_clipboard : Ctrl+Shift+Alt+c >> >> error opening security policy file /usr/local/share/nx/SecurityPolicy >> >> Info: Keycode conversion auto-determined as on >> >> Session: Session started at 'Mon Jan 19 22:50:04 2026'. >> >> Info: Screen [0] resized to geometry [1280x965] fullscreen [0]. >> >> >> >> At this stage the nxagent window fired up in the server side, has been >> >> drawn in the client desktop environment as a separate window. >> >> >> >> >> >> >> >> >> >> On Mon, Jan 19, 2026 at 9:42 PM Ulrich Sibiller >> >> <[email protected]> wrote: >> >>> >> >>> Hi, >> >>> >> >>> You are using nxproxy 3 >> >>> 5.99.23 which should not be a problem, despite being very old. But maybe >> >>> you are also using this ancient version on the server. Which IS a >> >>> problem. Please ensure you use 3.5.99.26 or 27. >> >>> >> >>> A quick test to rule out some things: ssh -X ro the server, then run >> >>> nxagent :55. Do you see an nxagent window? >> >>> >> >>> Also, are you sure you have an X desktop running on the server and not >> >>> wayland? And on the client? >> >>> >> >>> Uli >> >>> >> >>> >> >>> >> >>> Athanasios Silis <[email protected]> schrieb am Mo., 19. Jan. >> >>> 2026, 19:34: >> >>>> >> >>>> Hi all, >> >>>> I recently installed x2goserver (and x2goclient but this is probably >> >>>> not relevant in this case) on a fresh slackware-current system. >> >>>> >> >>>> Then, using x2goclients from other computers (other slackware64-15.0, >> >>>> ubuntu20.04 and 24.04 and debian systems) I want to "fetch" a desktop >> >>>> from this fresh system to one of the other client systems. >> >>>> >> >>>> The connection seems to go through normally but I never see a desktop >> >>>> window poping up. I have tried "xfce" and "fluxbox" (as a custom >> >>>> command) both of which have been faithfully working in the past and in >> >>>> other installations. >> >>>> >> >>>> I used `x2goclient --debug` to invoke the session and see if there are >> >>>> any meaningful messages error messages from the client side, but I have >> >>>> not been able to figure out if there is anything relevant: >> >>>> >> >>>> $ x2goclient --debug >> >>>> qt5ct: using qt5ct plugin >> >>>> x2go-INFO-1> "Starting X2Go Client 4.1.2.2..." >> >>>> [...] >> >>>> x2go-INFO-3> "Started X2Go Client." >> >>>> [...] >> >>>> x2go-INFO-8> "Starting connection to server: x.x.x.x:22" >> >>>> [...] >> >>>> x2go-DEBUG-../src/sshmasterconnection.cpp:687> User authentication >> >>>> OK. >> >>>> [...] >> >>>> x2go-DEBUG-../src/sshmasterconnection.cpp:702> Login Check - OK >> >>>> x2go-DEBUG-../src/onmainwindow.cpp:2947> SSH connection established. >> >>>> x2go-DEBUG-../src/onmainwindow.cpp:3374> Continue normal X2Go >> >>>> session >> >>>> [...] >> >>>> x2go-DEBUG-../src/sshprocess.cpp:387> Starting tunnel via >> >>>> SshProcess object 2: "localhost":57842 -> "localhost":58842 >> >>>> [...] >> >>>> x2go-DEBUG-../src/sshmasterconnection.cpp:2065> Executing remote: >> >>>> "bash -l -c 'echo >> >>>> \"X2GODATABEGIN:1790db9f-7b15-48ca-9eec-7596bdb1cccf\"; export >> >>>> PATH=\"/usr/local/bin:/usr/bin:/bin\";export TERM=\"dumb\"; X2GODPI=141 >> >>>> X2GO_XINERAMA=no x2gostartagent 800x600 adsl 16m-jpeg-9 >> >>>> unix-kde-depth_24 us auto 1 D startfluxbox both; echo >> >>>> \"X2GODATAEND:1790db9f-7b15-48ca-9eec-7596bdb1cccf\";'" >> >>>> x2go-DEBUG-../src/onmainwindow.cpp:6142> "Starting NX proxy, >> >>>> command: nxproxy -S >> >>>> nx/nx,options=/home/user/.x2go/S-poker-50-1768844727_stDstartfluxbox_dp24/options:50" >> >>>> [...] >> >>>> x2go-DEBUG-../src/onmainwindow.cpp:6618> Proxy wrote on stderr: >> >>>> "\nNXPROXY - Version 3.5.99.23\n\nCopyright (c) 2001, 2011 >> >>>> NoMachine[...] >> >>>> Info: Connecting to remote host 'localhost:58842'.\n >> >>>> Info: Connected to remote proxy on FD#5.\n" >> >>>> >> >>>> >> >>>> So it seems ssh connection gets established, login is OK, >> >>>> `nxstartagent` is executed fine, and `nxproxy` also starts without >> >>>> errors. but then >> >>>> >> >>>> >> >>>> >> >>>> 2go-DEBUG-../src/sshprocess.cpp:109> New TCP connection. >> >>>> x2go-DEBUG-../src/sshprocess.cpp:114> New socket: 21 >> >>>> x2go-DEBUG-../src/onmainwindow.cpp:11659> "Searching proxy window: >> >>>> X2GO-nass-50-1768844727_stDstartfluxbox_dp24" >> >>>> x2go-DEBUG-../src/onmainwindow.cpp:13278> "Searching window with >> >>>> title: X2GO-nass-50-1768844727_stDstartfluxbox_dp24" >> >>>> x2go-DEBUG-../src/sshmasterconnection.cpp:1977> Creating new >> >>>> channel. >> >>>> >> >>>> x2go-DEBUG-../src/sshmasterconnection.cpp:1990> New >> >>>> channel:0x7f5b580102e0 >> >>>> >> >>>> x2go-DEBUG-../src/sshmasterconnection.cpp:1994> Forwarding >> >>>> parameters: from remote ("localhost":57842) to local ("localhost":35710) >> >>>> x2go-DEBUG-../src/sshmasterconnection.cpp:2028> Temporary session >> >>>> port after config file parse: 57842 >> >>>> x2go-DEBUG-../src/sshmasterconnection.cpp:2032> Temporary session >> >>>> host after config file parse: localhost >> >>>> x2go-DEBUG-../src/onmainwindow.cpp:11659> "Searching proxy window: >> >>>> X2GO-nass-50-1768844727_stDstartfluxbox_dp24" >> >>>> x2go-DEBUG-../src/onmainwindow.cpp:13278> "Searching window with >> >>>> title: X2GO-nass-50-1768844727_stDstartfluxbox_dp24" >> >>>> x2go-DEBUG-../src/onmainwindow.cpp:11659> "Searching proxy window: >> >>>> X2GO-nass-50-1768844727_stDstartfluxbox_dp24" >> >>>> x2go-DEBUG-../src/onmainwindow.cpp:13278> "Searching window with >> >>>> title: X2GO-nass-50-1768844727_stDstartfluxbox_dp24" >> >>>> x2go-DEBUG-../src/onmainwindow.cpp:11659> "Searching proxy window: >> >>>> X2GO-nass-50-1768844727_stDstartfluxbox_dp24" >> >>>> x2go-DEBUG-../src/onmainwindow.cpp:13278> "Searching window with >> >>>> title: X2GO-nass-50-1768844727_stDstartfluxbox_dp24" >> >>>> [...] >> >>>> x2go-DEBUG-../src/onmainwindow.cpp:6618> Proxy wrote on stderr: >> >>>> "Info: Aborting the procedure due to signal '15'.\nSession: Session >> >>>> terminated at 'Mon Jan 19 19:46:53 2026'.\n" >> >>>> x2go-DEBUG-../src/onmainwindow.cpp:6475> Deleting Proxy. >> >>>> x2go-DEBUG-../src/onmainwindow.cpp:6520> Waiting for proxy to exit. >> >>>> x2go-DEBUG-../src/onmainwindow.cpp:6544> Checking exit status. >> >>>> x2go-DEBUG-../src/sshprocess.cpp:199> Executing remote command via >> >>>> SshProcess object 3: "x2gocmdexitmessage >> >>>> nass-50-1768844727_stDstartfluxbox_dp24" >> >>>> x2go-DEBUG-../src/sshprocess.cpp:213> >> >>>> this=SshProcess(0x55f9bbed6c50) Running >> >>>> masterCon->addChannelConnection(this, >> >>>> '"475b1d25-5fe0-4e44-abcc-dea30df785f1"', '"bash -l -c 'echo >> >>>> \"X2GODATABEGIN:475b1d25-5fe0-4e44-abcc-dea30df785f1\"; export >> >>>> PATH=\"/usr/local/bin:/usr/bin:/bin\";export TERM=\"dumb\"; >> >>>> x2gocmdexitmessage nass-50-1768844727_stDstartfluxbox_dp24; echo \""'); >> >>>> x2go-DEBUG-../src/sshmasterconnection.cpp:1810> Locking SSH channel >> >>>> connection MUTEX. >> >>>> x2go-DEBUG-../src/sshmasterconnection.cpp:2055> >> >>>> "ssh_channel_open_forward failed": "No channel request of this type >> >>>> from server" >> >>>> >> >>>> x2go-DEBUG-../src/sshmasterconnection.cpp:2187> "ssh_channel_write >> >>>> failed": "Remote channel is closed" >> >>>> >> >>>> then it tries to resume >> >>>> >> >>>> x2go-DEBUG-../src/sshmasterconnection.cpp:2065> Executing remote: >> >>>> "bash -l -c 'echo >> >>>> \"X2GODATABEGIN:a6aca35a-a72c-4453-96b1-0a2e1b49dfcb\"; export >> >>>> PATH=\"/usr/local/bin:/usr/bin:/bin\";export TERM=\"dumb\"; >> >>>> x2goresume-session nass-50-1768844727_stDstartfluxbox_dp24 800x600 adsl >> >>>> 16m-jpeg-9 us auto 1 both no; echo >> >>>> \"X2GODATAEND:a6aca35a-a72c-4453-96b1-0a2e1b49dfcb\";'" >> >>>> >> >>>> x2go-DEBUG-../src/sshmasterconnection.cpp:2071> >> >>>> "ssh_channel_open_session failed": "Socket error: Success" >> >>>> >> >>>> x2go-DEBUG-../src/onmainwindow.cpp:11659> "Searching proxy window: >> >>>> X2GO-nass-50-1768844727_stDstartfluxbox_dp24" >> >>>> x2go-DEBUG-../src/onmainwindow.cpp:13278> "Searching window with >> >>>> title: X2GO-nass-50-1768844727_stDstartfluxbox_dp24" >> >>>> x2go-DEBUG-../src/sshprocess.cpp:478> I/O error: >> >>>> "ssh_channel_open_forward failed."" - No channel request of this type >> >>>> from server" (2). >> >>>> x2go-DEBUG-../src/sshprocess.cpp:478> I/O error: "ssh_channel_write >> >>>> failed."" - Remote channel is closed" (2). >> >>>> x2go-DEBUG-../src/sshprocess.cpp:478> I/O error: >> >>>> "ssh_channel_open_session failed."" - Received SSH_MSG_DISCONNECT: >> >>>> 2:oclose packet referred to nonexistent channel 0" (3). >> >>>> x2go-DEBUG-../src/sshprocess.cpp:478> I/O error: >> >>>> "ssh_channel_open_session failed."" - Socket error: Success" (4). >> >>>> x2go-DEBUG-../src/onmainwindow.cpp:11659> "Searching proxy window: >> >>>> X2GO-nass-50-1768844727_stDstartfluxbox_dp24" >> >>>> x2go-DEBUG-../src/onmainwindow.cpp:13278> "Searching window with >> >>>> title: X2GO-nass-50-1768844727_stDstartfluxbox_dp24" >> >>>> x2go-DEBUG-../src/onmainwindow.cpp:11659> "Searching proxy window: >> >>>> X2GO-nass-50-1768844727_stDstartfluxbox_dp24" >> >>>> x2go-DEBUG-../src/onmainwindow.cpp:13278> "Searching window with >> >>>> title: X2GO-nass-50-1768844727_stDstartfluxbox_dp24" >> >>>> >> >>>> and afterwards I get the last 2 messages in an endless loop. No desktop >> >>>> window pops up. >> >>>> >> >>>> >> >>>> I am also very confused about the >> >>>> >> >>>> "ssh_channel_open_session failed": "Socket error: Success" >> >>>> >> >>>> >> >>>> I have not found any information about how to enable debug output in >> >>>> the server side (only on the client side) and the current messages do >> >>>> not give me a clear view as to what is wrong. >> >>>> >> >>>> Do you have any idea which way I should look next? >> >>>> >> >>>> Thank you in advance for your help. >> >>>> >> >>>> >> >>>> _______________________________________________ >> >>>> x2go-user mailing list -- [email protected] >> >>>> To unsubscribe send an email to [email protected] >> >>>> ${mailinglist_url} (substitution broken, will need mailman upgrade) >> >>>> https://lists.x2go.org/postorius/lists/x2go-user.lists.x2go.org _______________________________________________ x2go-user mailing list -- [email protected] To unsubscribe send an email to [email protected] ${mailinglist_url} (substitution broken, will need mailman upgrade) https://lists.x2go.org/postorius/lists/x2go-user.lists.x2go.org
