Operating Systems 2014F: Assignment 9 - Revision history

https://homeostasis.scs.carleton.ca/wiki/index.php?action=history&feed=atom&title=Operating_Systems_2014F%3A_Assignment_9 Operating Systems 2014F: Assignment 9 - Revision history 2026-06-02T22:28:07Z Revision history for this page on the wiki MediaWiki 1.42.1 https://homeostasis.scs.carleton.ca/wiki/index.php?title=Operating_Systems_2014F:_Assignment_9&diff=19567&oldid=prev Soma at 20:05, 11 December 2014 2014-12-11T20:05:30Z

<p></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 20:05, 11 December 2014</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l17">Line 17:</td> <td colspan="2" class="diff-lineno">Line 17:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># Processes check their environment variables for the SSH_AUTH_SOCK variable. If this exists, its value contains information on how to connect to the user's authentication agent. This environment variable is propagated as all environment variables are, from parent to child processes and as arguments to execve system calls.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># Processes check their environment variables for the SSH_AUTH_SOCK variable. If this exists, its value contains information on how to connect to the user's authentication agent. This environment variable is propagated as all environment variables are, from parent to child processes and as arguments to execve system calls.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># sshfs cannot control the file to inode mappings on the remote system because it can only do what regular processes on the remote system can do (i.e., the remote sftp-server process). Processes cannot directly specify inodes to file operations because doing so could allow file access controls to be bypassed (e.g., accessing a world-readable file inside of a private directory). Having said this, sshfs *must* specify the file to inode mappings locally (on the host running sshfs), as this is a key part of implementing a filesystem. The locally specified inode numbers are completely arbitrary and have nothing to do with the specific inodes on the remote system, to the point that hard linked files on the remote system have different inode numbers.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># sshfs cannot control the file to inode mappings on the remote system because it can only do what regular processes on the remote system can do (i.e., the remote sftp-server process). Processes cannot directly specify inodes to file operations because doing so could allow file access controls to be bypassed (e.g., accessing a world-readable file inside of a private directory). Having said this, sshfs *must* specify the file to inode mappings locally (on the host running sshfs), as this is a key part of implementing a filesystem. The locally specified inode numbers are completely arbitrary and have nothing to do with the specific inodes on the remote system, to the point that hard linked files on the remote system have different inode numbers.</div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"># sshfs creates two processes on the local (mounting) machine: an sshfs process and an ssh one. The sshfs process takes care of the FUSE part, i.e., it implements the actual filesystem semantics for the kernel. The ssh process communicates with the remote system, handling the transfer of data back and forth.</ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"># If you kill any of the sshfs-related processes on a remote system they all terminate, as they are all highly dependent upon each other. Their termination closes the network connection, causing the local ssh process to terminate. The sshfs process notices that ssh has terminated and then itself terminates after releasing the mountpoint (doing the equivalent to fusermount -u). After all of this the sshfs filesystem is no longer mounted. If any process accessing files or directories under the mountpoint they will get errors such as "Transport endpoint is not connected"; new accesses to the mountpoint will just see it as an empty directory (FUSE doesn't normally allow the use of non-empty directories as mountpoints).</ins></div></td></tr> </table>

Soma https://homeostasis.scs.carleton.ca/wiki/index.php?title=Operating_Systems_2014F:_Assignment_9&diff=19565&oldid=prev Soma: /* Solutions */ 2014-12-11T18:48:44Z

<p><span dir="auto"><span class="autocomment">Solutions</span></span></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 18:48, 11 December 2014</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l16">Line 16:</td> <td colspan="2" class="diff-lineno">Line 16:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># The friend is saying that you can do an sshfs mount to localhost, e.g., "sshfs other@localhost: other-files" and all of the files of user other will appear in the directory other-files. You can then copy files back and forth between these two users without having to do any file permission modifications, because the files of the other user can now all be accessed and changed, just as they can be accessed and changed by the other user when they are logged in. The weird part of this is if you look at the owner and group of the files in other-files you will see that they are in fact still "owned" by the other user. A strict interpretation of the file permissions would make one think these files are NOT accessible, when in fact they are. It turns out sshfs by default just fills in the user and group from the remote system even though they essentially have no meaning locally. Access to files is determined on the remote side, not locally, so the spurious information doesn't actually change how things behave. They are just confusing. (There are options to sshfs that allow the user and group of files to be mapped to other values.)</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># The friend is saying that you can do an sshfs mount to localhost, e.g., "sshfs other@localhost: other-files" and all of the files of user other will appear in the directory other-files. You can then copy files back and forth between these two users without having to do any file permission modifications, because the files of the other user can now all be accessed and changed, just as they can be accessed and changed by the other user when they are logged in. The weird part of this is if you look at the owner and group of the files in other-files you will see that they are in fact still "owned" by the other user. A strict interpretation of the file permissions would make one think these files are NOT accessible, when in fact they are. It turns out sshfs by default just fills in the user and group from the remote system even though they essentially have no meaning locally. Access to files is determined on the remote side, not locally, so the spurious information doesn't actually change how things behave. They are just confusing. (There are options to sshfs that allow the user and group of files to be mapped to other values.)</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># Processes check their environment variables for the SSH_AUTH_SOCK variable. If this exists, its value contains information on how to connect to the user's authentication agent. This environment variable is propagated as all environment variables are, from parent to child processes and as arguments to execve system calls.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># Processes check their environment variables for the SSH_AUTH_SOCK variable. If this exists, its value contains information on how to connect to the user's authentication agent. This environment variable is propagated as all environment variables are, from parent to child processes and as arguments to execve system calls.</div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div># sshfs cannot control the file to inode mappings on the remote system because it can only do what regular processes on the remote system can do (i.e., the remote sftp-server process). Processes cannot directly specify inodes to file operations because doing so could allow file access controls to be bypassed (e.g., accessing a world-readable file inside of a private directory). Having said this, sshfs *must* specify the file to inode mappings locally (on the host running sshfs), as this is a key part of implementing a filesystem.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div># sshfs cannot control the file to inode mappings on the remote system because it can only do what regular processes on the remote system can do (i.e., the remote sftp-server process). Processes cannot directly specify inodes to file operations because doing so could allow file access controls to be bypassed (e.g., accessing a world-readable file inside of a private directory). Having said this, sshfs *must* specify the file to inode mappings locally (on the host running sshfs), as this is a key part of implementing a filesystem<ins style="font-weight: bold; text-decoration: none;">. The locally specified inode numbers are completely arbitrary and have nothing to do with the specific inodes on the remote system, to the point that hard linked files on the remote system have different inode numbers</ins>.</div></td></tr> </table>

Soma https://homeostasis.scs.carleton.ca/wiki/index.php?title=Operating_Systems_2014F:_Assignment_9&diff=19564&oldid=prev Soma at 18:46, 11 December 2014 2014-12-11T18:46:32Z

<p></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 18:46, 11 December 2014</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l16">Line 16:</td> <td colspan="2" class="diff-lineno">Line 16:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># The friend is saying that you can do an sshfs mount to localhost, e.g., "sshfs other@localhost: other-files" and all of the files of user other will appear in the directory other-files. You can then copy files back and forth between these two users without having to do any file permission modifications, because the files of the other user can now all be accessed and changed, just as they can be accessed and changed by the other user when they are logged in. The weird part of this is if you look at the owner and group of the files in other-files you will see that they are in fact still "owned" by the other user. A strict interpretation of the file permissions would make one think these files are NOT accessible, when in fact they are. It turns out sshfs by default just fills in the user and group from the remote system even though they essentially have no meaning locally. Access to files is determined on the remote side, not locally, so the spurious information doesn't actually change how things behave. They are just confusing. (There are options to sshfs that allow the user and group of files to be mapped to other values.)</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># The friend is saying that you can do an sshfs mount to localhost, e.g., "sshfs other@localhost: other-files" and all of the files of user other will appear in the directory other-files. You can then copy files back and forth between these two users without having to do any file permission modifications, because the files of the other user can now all be accessed and changed, just as they can be accessed and changed by the other user when they are logged in. The weird part of this is if you look at the owner and group of the files in other-files you will see that they are in fact still "owned" by the other user. A strict interpretation of the file permissions would make one think these files are NOT accessible, when in fact they are. It turns out sshfs by default just fills in the user and group from the remote system even though they essentially have no meaning locally. Access to files is determined on the remote side, not locally, so the spurious information doesn't actually change how things behave. They are just confusing. (There are options to sshfs that allow the user and group of files to be mapped to other values.)</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># Processes check their environment variables for the SSH_AUTH_SOCK variable. If this exists, its value contains information on how to connect to the user's authentication agent. This environment variable is propagated as all environment variables are, from parent to child processes and as arguments to execve system calls.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># Processes check their environment variables for the SSH_AUTH_SOCK variable. If this exists, its value contains information on how to connect to the user's authentication agent. This environment variable is propagated as all environment variables are, from parent to child processes and as arguments to execve system calls.</div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"># sshfs cannot control the file to inode mappings on the remote system because it can only do what regular processes on the remote system can do (i.e., the remote sftp-server process). Processes cannot directly specify inodes to file operations because doing so could allow file access controls to be bypassed (e.g., accessing a world-readable file inside of a private directory). Having said this, sshfs *must* specify the file to inode mappings locally (on the host running sshfs), as this is a key part of implementing a filesystem.</ins></div></td></tr> </table>

Soma https://homeostasis.scs.carleton.ca/wiki/index.php?title=Operating_Systems_2014F:_Assignment_9&diff=19563&oldid=prev Soma at 18:26, 11 December 2014 2014-12-11T18:26:02Z

<p></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 18:26, 11 December 2014</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l15">Line 15:</td> <td colspan="2" class="diff-lineno">Line 15:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>===Solutions===</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>===Solutions===</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># The friend is saying that you can do an sshfs mount to localhost, e.g., "sshfs other@localhost: other-files" and all of the files of user other will appear in the directory other-files. You can then copy files back and forth between these two users without having to do any file permission modifications, because the files of the other user can now all be accessed and changed, just as they can be accessed and changed by the other user when they are logged in. The weird part of this is if you look at the owner and group of the files in other-files you will see that they are in fact still "owned" by the other user. A strict interpretation of the file permissions would make one think these files are NOT accessible, when in fact they are. It turns out sshfs by default just fills in the user and group from the remote system even though they essentially have no meaning locally. Access to files is determined on the remote side, not locally, so the spurious information doesn't actually change how things behave. They are just confusing. (There are options to sshfs that allow the user and group of files to be mapped to other values.)</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># The friend is saying that you can do an sshfs mount to localhost, e.g., "sshfs other@localhost: other-files" and all of the files of user other will appear in the directory other-files. You can then copy files back and forth between these two users without having to do any file permission modifications, because the files of the other user can now all be accessed and changed, just as they can be accessed and changed by the other user when they are logged in. The weird part of this is if you look at the owner and group of the files in other-files you will see that they are in fact still "owned" by the other user. A strict interpretation of the file permissions would make one think these files are NOT accessible, when in fact they are. It turns out sshfs by default just fills in the user and group from the remote system even though they essentially have no meaning locally. Access to files is determined on the remote side, not locally, so the spurious information doesn't actually change how things behave. They are just confusing. (There are options to sshfs that allow the user and group of files to be mapped to other values.)</div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>#</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div># <ins style="font-weight: bold; text-decoration: none;">Processes check their environment variables for the SSH_AUTH_SOCK variable. If this exists, its value contains information on how to connect to the user's authentication agent. This environment variable is propagated as all environment variables are, from parent to child processes and as arguments to execve system calls.</ins></div></td></tr> </table>

Soma https://homeostasis.scs.carleton.ca/wiki/index.php?title=Operating_Systems_2014F:_Assignment_9&diff=19562&oldid=prev Soma at 17:02, 11 December 2014 2014-12-11T17:02:19Z

<p></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 17:02, 11 December 2014</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l12">Line 12:</td> <td colspan="2" class="diff-lineno">Line 12:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># [2] How many background processes does mounting a remote filesystem over sshfs create on the client? What do each of them do?</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># [2] How many background processes does mounting a remote filesystem over sshfs create on the client? What do each of them do?</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># [2] If you kill the ssh-related processes on the server (without touching those on the client) while a filesystem is mounted via sshfs, what happens to that filesystem? Why? (Describe the behaviour and give a basic explanation for it.)</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># [2] If you kill the ssh-related processes on the server (without touching those on the client) while a filesystem is mounted via sshfs, what happens to that filesystem? Why? (Describe the behaviour and give a basic explanation for it.)</div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">===Solutions===</ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"># The friend is saying that you can do an sshfs mount to localhost, e.g., "sshfs other@localhost: other-files" and all of the files of user other will appear in the directory other-files. You can then copy files back and forth between these two users without having to do any file permission modifications, because the files of the other user can now all be accessed and changed, just as they can be accessed and changed by the other user when they are logged in. The weird part of this is if you look at the owner and group of the files in other-files you will see that they are in fact still "owned" by the other user. A strict interpretation of the file permissions would make one think these files are NOT accessible, when in fact they are. It turns out sshfs by default just fills in the user and group from the remote system even though they essentially have no meaning locally. Access to files is determined on the remote side, not locally, so the spurious information doesn't actually change how things behave. They are just confusing. (There are options to sshfs that allow the user and group of files to be mapped to other values.)</ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">#</ins></div></td></tr> </table>

Soma https://homeostasis.scs.carleton.ca/wiki/index.php?title=Operating_Systems_2014F:_Assignment_9&diff=19524&oldid=prev Soma at 19:28, 2 December 2014 2014-12-02T19:28:07Z

<p></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 19:28, 2 December 2014</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l1">Line 1:</td> <td colspan="2" class="diff-lineno">Line 1:</td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Please submit the answers to the following questions via CULearn by just before <del style="font-weight: bold; text-decoration: none;">midnight </del>(<del style="font-weight: bold; text-decoration: none;">11</del>:<del style="font-weight: bold; text-decoration: none;">55 PM</del>) on <del style="font-weight: bold; text-decoration: none;">Thursday</del>, December <del style="font-weight: bold; text-decoration: none;">4</del>, 2014. There 10 points in 5 questions.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Please submit the answers to the following questions via CULearn by just before <ins style="font-weight: bold; text-decoration: none;">class </ins>(<ins style="font-weight: bold; text-decoration: none;">8</ins>:<ins style="font-weight: bold; text-decoration: none;">30 AM</ins>) on <ins style="font-weight: bold; text-decoration: none;">Friday</ins>, December <ins style="font-weight: bold; text-decoration: none;">5</ins>, 2014. There 10 points in 5 questions.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Submit your answers as a single text file named "<username>-comp3000-assign9.txt" (where username is your MyCarletonOne username). The first four lines of this file should be "COMP 3000 Assignment 9", your name, student number, and the date of submission. You may wish to format your answers in [http://en.wikipedia.org/wiki/Markdown Markdown] to improve their appearance.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Submit your answers as a single text file named "<username>-comp3000-assign9.txt" (where username is your MyCarletonOne username). The first four lines of this file should be "COMP 3000 Assignment 9", your name, student number, and the date of submission. You may wish to format your answers in [http://en.wikipedia.org/wiki/Markdown Markdown] to improve their appearance.</div></td></tr> </table>

Soma https://homeostasis.scs.carleton.ca/wiki/index.php?title=Operating_Systems_2014F:_Assignment_9&diff=19521&oldid=prev Soma at 04:40, 1 December 2014 2014-12-01T04:40:06Z

<p></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 04:40, 1 December 2014</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l1">Line 1:</td> <td colspan="2" class="diff-lineno">Line 1:</td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><del style="font-weight: bold; text-decoration: none;">'''This assignment is not yet finalized (but it is close).'''</del></div></td><td colspan="2" class="diff-side-added"></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><del style="font-weight: bold; text-decoration: none;"></del></div></td><td colspan="2" class="diff-side-added"></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Please submit the answers to the following questions via CULearn by just before midnight (11:55 PM) on Thursday, December 4, 2014. There 10 points in 5 questions.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Please submit the answers to the following questions via CULearn by just before midnight (11:55 PM) on Thursday, December 4, 2014. There 10 points in 5 questions.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> <tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l11">Line 11:</td> <td colspan="2" class="diff-lineno">Line 9:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># [2] A friend says to you that "a loopback mount over sshfs makes it easy to temporarily share files between users without changing file permissions." Explain what your friend is saying, explaining a "loopback mount" and how they interact with file permissions. (Note you may see some weird behavior!)</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># [2] A friend says to you that "a loopback mount over sshfs makes it easy to temporarily share files between users without changing file permissions." Explain what your friend is saying, explaining a "loopback mount" and how they interact with file permissions. (Note you may see some weird behavior!)</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># [2] How do processes find out that an authentication agent (ssh-agent or similar) is running and will accept connections from them? How would you expect this information to be propagated between applications?</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># [2] How do processes find out that an authentication agent (ssh-agent or similar) is running and will accept connections from them? How would you expect this information to be propagated between applications?</div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div># [2] Can sshfs directly control <del style="font-weight: bold; text-decoration: none;">while file is associated with which </del>inode on the remote system (that is being mounted)? Explain briefly.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div># [2] Can sshfs directly control <ins style="font-weight: bold; text-decoration: none;">filename to </ins>inode <ins style="font-weight: bold; text-decoration: none;">mappings </ins>on the remote system (that is being mounted)? Explain briefly.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># [2] How many background processes does mounting a remote filesystem over sshfs create on the client? What do each of them do?</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># [2] How many background processes does mounting a remote filesystem over sshfs create on the client? What do each of them do?</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># [2] If you kill the ssh-related processes on the server (without touching those on the client) while a filesystem is mounted via sshfs, what happens to that filesystem? Why? (Describe the behaviour and give a basic explanation for it.)</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># [2] If you kill the ssh-related processes on the server (without touching those on the client) while a filesystem is mounted via sshfs, what happens to that filesystem? Why? (Describe the behaviour and give a basic explanation for it.)</div></td></tr> </table>

Soma https://homeostasis.scs.carleton.ca/wiki/index.php?title=Operating_Systems_2014F:_Assignment_9&diff=19516&oldid=prev Soma at 19:21, 28 November 2014 2014-11-28T19:21:10Z

<p></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 19:21, 28 November 2014</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l1">Line 1:</td> <td colspan="2" class="diff-lineno">Line 1:</td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">'''This assignment is not yet finalized (but it is close).'''</ins></div></td></tr> <tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Please submit the answers to the following questions via CULearn by just before midnight (11:55 PM) on Thursday, December 4, 2014. There 10 points in 5 questions.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Please submit the answers to the following questions via CULearn by just before midnight (11:55 PM) on Thursday, December 4, 2014. There 10 points in 5 questions.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> </table>

Soma https://homeostasis.scs.carleton.ca/wiki/index.php?title=Operating_Systems_2014F:_Assignment_9&diff=19515&oldid=prev Soma at 19:20, 28 November 2014 2014-11-28T19:20:51Z

<p></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 19:20, 28 November 2014</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l1">Line 1:</td> <td colspan="2" class="diff-lineno">Line 1:</td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><del style="font-weight: bold; text-decoration: none;">'''This assignment is not yet finalized.'''</del></div></td><td colspan="2" class="diff-side-added"></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><del style="font-weight: bold; text-decoration: none;"></del></div></td><td colspan="2" class="diff-side-added"></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Please submit the answers to the following questions via CULearn by just before midnight (11:55 PM) on Thursday, December 4, 2014. There 10 points in 5 questions.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Please submit the answers to the following questions via CULearn by just before midnight (11:55 PM) on Thursday, December 4, 2014. There 10 points in 5 questions.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr> </table>

Soma https://homeostasis.scs.carleton.ca/wiki/index.php?title=Operating_Systems_2014F:_Assignment_9&diff=19510&oldid=prev Soma at 18:24, 28 November 2014 2014-11-28T18:24:48Z

<p></p> <table style="background-color: #fff; color: #202122;" data-mw="interface"> <col class="diff-marker" /> <col class="diff-content" /> <col class="diff-marker" /> <col class="diff-content" /> <tr class="diff-title" lang="en"> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td> <td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 18:24, 28 November 2014</td> </tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l13">Line 13:</td> <td colspan="2" class="diff-lineno">Line 13:</td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># [2] Can sshfs directly control while file is associated with which inode on the remote system (that is being mounted)? Explain briefly.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># [2] Can sshfs directly control while file is associated with which inode on the remote system (that is being mounted)? Explain briefly.</div></td></tr> <tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># [2] How many background processes does mounting a remote filesystem over sshfs create on the client? What do each of them do?</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div># [2] How many background processes does mounting a remote filesystem over sshfs create on the client? What do each of them do?</div></td></tr> <tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div># [2] If you kill the ssh-related processes on the server (without touching those on the client) while a filesystem is mounted via sshfs, what happens to that filesystem? Why? (<del style="font-weight: bold; text-decoration: none;">Explain </del>the behaviour and give a basic explanation for it.)</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div># [2] If you kill the ssh-related processes on the server (without touching those on the client) while a filesystem is mounted via sshfs, what happens to that filesystem? Why? (<ins style="font-weight: bold; text-decoration: none;">Describe </ins>the behaviour and give a basic explanation for it.)</div></td></tr> </table>

Soma