--- name: "aide.conf" section: "5" platform: "linux" package: "aide" version: "0.19.1-2+deb13u2" release: "Debian 13 (Trixie)" platforms: ["linux"] url: "https://new.carta.tech/aide.conf" --- # aide.conf(5) The configuration file for Advanced Intrusion Detection Environment ## NAME aide.conf - The configuration file for Advanced Intrusion Detection Environment ## SYNOPSIS **aide.conf** is the configuration file for Advanced Intrusion Detection Environment. **aide.conf** contains the runtime configuration aide uses to initialize or check the AIDE database. ## FILE FORMAT aide.conf is case-sensitive. Leading and trailing white spaces are ignored. Each config line must end with new line. AIDE uses the backslash character (**\\**) as escape character for ' ' (space), '@' and '\\' (backslash) (e.g. '\\ ' or '\\@'). To literally match a '**\\**' in a file path with a regular expression you have to escape the backslash twice (i.e. '**\\\\\\\\**'). There are three types of lines in **aide.conf**. First there are the configuration options which are used to set configuration parameters and define groups. Second, there are (restricted) rules that are used to indicate which files/directoires from the file system are added to the database. Third, macro lines define or undefine variables within the config file. Lines beginning with # are ignored as comments. ## CONFIG OPTIONS These lines have the format parameter=value. See URLS for a list of valid urls. - database\_in (type: URL, default: see **--version** output, added in AIDE v0.17) database (REMOVED in AIDE v0.19) The url from which database is read. There can only be one of these lines. If there are multiple database lines then the first is used. **Examples:** ``` database_in=file:/var/lib/aide/aide.db ``` Read database locally from */var/lib/aide/aide.db*. ``` database_in=stdin ``` Read database from *stdin*. ``` database_in=https://example.com/aide.db ``` Read database remotely from *https://example.com/aide.db*. - database\_out (type: URL, default: see **--version** output) The url to which the new database is written to. There can only be one of these lines. If there are multiple database\_out lines then the first is used. - database\_new (type: URL, default: **\**) The url from which the other database for --compare is read. - database\_attrs (type: attribute expression, default: **H**, added in AIDE v0.16) The attributes of the (uncompressed) database files which are to be added to the reports in report level \>= **database\_attributes** . Only checksum attributes are supported. To disable set *database\_attrs* to '**E**'. - database\_add\_metadata (type: bool, default: **true**, added in AIDE v0.16) Whether to add the AIDE version and the time of database generation as comments to the database file or not. This option may be set to false by default in a future release. - log\_level (type: log level, default: **warning**, added in AIDE v0.17) The log level to use. Log messages are written to *stderr*. If there are multiple *log\_level* lines then the first one is used. The --log-level or -L command line option overwrites this option. The following log levels are available: **error**: show unrecoverable issues that have to be handled by the user. Errors are fatal to the AIDE process. **warning**: additionally show recoverable issues that most likely lead to unexpected behaviour and should be handled by the user **notice**: additionally show recoverable issues that sometimes lead to unexpected behaviour and might be handled by the user. **info**: additionally show informational messages **compare**: additionally show messages to help to debug file comparison and (special) attribute handling The log levels below are very verbose and can easily generate multiple gigabytes of log data (depending on the number of processed files and the size of the rule tree). For debugging it is recommended to use these log levels together with the *--limit* parameter (see aide (1) for details). **rule**: additionally show messages to help to debug the path rule matching **config**: additionally show messages to help to debug config and rule parsing **debug**: additionally show messages that are useful to debug the application **limit**: additionally show messages about skipped entries due to limit match **thread**: additionally show messages about thread processing (e.g. broadcast events) **trace**: additionallyt show messages about the internal data structures and the flow of the application (e.g. in-loop logging) (extremely verbose) - verbose (type: number, range: 0 - 255, default: **5**, REMOVED in AIDE v0.17) Removed, use **log\_level** and **report\_level** options instead. - gzip\_dbout (type: bool, default: **false**) Whether the output to the database is gzipped or not. This option is available only if zlib support is compiled in. - root\_prefix (type: path, default: **\**, added in AIDE v0.16) The prefix to strip from each file name in the file system before applying the rules and writing to database. AIDE removes a trailing slash from the prefix. If there are multiple root\_prefix lines then the first one is used. This option has no effect in compare mode. - acl\_no\_symlink\_follow (type: bool, default: **false**) Whether to check ACLs for symlinks or not. This option is available only if acl support is compiled in. - warn\_dead\_symlinks (type: path, default: **false**) Whether to warn about dead symlinks or not. - config\_version (type: string, default: **\**) The value of config\_version is printed in the report and also printed to the database. This is for informational purposes only. It has no other functionality. - config\_check\_warn\_unrestricted\_rules (type: bool, default: **false**, added in AIDE v0.18) Whether to warn on unrestricted rules during config check. To explicitly define unrestricted rules use **0** (zero) as restriction character. - num\_workers (type: number\|percentage, default: **1**, added in AIDE v0.18) Specifies the number of simultaneous workers (threads) for file attribute processing (i.a. hashsum calculation). The number of workers can be a positive integer (e.g. '4') or the percentage of the available processors (e.g. '60%'). The resulting number of workers is rounded up to the next integer (e.g. '60%' of 8 processors results in 5 workers). If there are multiple *num\_workers* lines then the first one is used. Use 0 (zero) to disable (multi-threaded) workers. The default value 1 (single worker thread) may be changed in a future release. ## REPORT OPTIONS - report\_url (type: URL, default: **stdout**) The URL that the output is written to. Multiple instances of the **report\_url** option are supported. **Examples:** ``` report_url=file:/var/log/aide.log ``` Write report to */var/log/aide.log*. ``` report_url=stdout ``` Write report to *stdout*. ``` report_url=syslog: ``` Write report to *syslog* using *LOG\_FACILITY*. The following report options are available (to take effect they have to be set before **report\_url**): - report\_level (type: report level, default: **changed\_attributes**, added in AIDE v0.17) The report level to use. The available report levels are as follows: **minimal**: print single line whether AIDE found differences to the database **summary**: additionally print number of added, removed and changed files **database\_attributes**: additionally print database checksums **list\_entries**: additionally print lists of added, removed and changed entries **changed\_attributes**: additionally print details about changed entries **Example:** ``` File: /var/lib/apt/extended_states Perm : -rw-r--r-- | -rw------- Uid : 0 | 106 ``` The left column shows the old value (e.g. from the *database\_in* database) and the right column shows the new value (e.g. from the file system). **added\_removed\_attributes**: additionally print details about added and removed attributes **added\_removed\_entries**: additionally print details about added and removed entries - report\_format (type: report format, default: **plain**, added in AIDE v0.18) The report format to use. The available report formats are as follows: **plain**: Print report in plain human-readable format. **json**: Print report in json machine-readable format. - report\_base16 (type: bool, default: **false**, added in AIDE v0.17) Base16 encode the checksums in the report. The default is to report checksums in base64 encoding. - report\_detailed\_init (type: bool, default: **false**, added in AIDE v0.16) Report added files (report level \>= **list\_entries**) and their details (report level \>= **added\_removed\_entries**) in initialization mode. - report\_quiet (type: bool, default: **false**, added in AIDE v0.16) Suppress report output if no differences to the database have been found. - report\_append (type: bool, default: **false**, added in AIDE v0.17) Append to the report URL. - report\_grouped (type: bool, default: **true**, added in AIDE v0.17) grouped (REMOVED in AIDE v0.19) Group the files in the report by added, removed and changed files. - report\_summarize\_changes (type: bool, default: **true**, added in AIDE v0.17) summarize\_changes (REMOVED in AIDE v0.19) Summarize changes in the added, removed and changed files sections of the report. The general format is like the string YlZbpugamcinHAXSECF, where Y is replaced by the file-type ('**f**' for a regular file, '**d**' for a directory, '**l**' for a symbolic link, '**c**' for a character device, '**b**' for a block device, '**p**' for a FIFO, '**s**' for a unix socket, '**D**' for a Solaris door, '**P**' for a Solaris event port, '**!**' if file type has changed and '**?**' otherwise). The Z is replaced as follows: A '**=**' means that the size has not changed, a '**\<**' reports a shrinked size and a '**\>**' reports a grown size. The other letters in the string are the actual letters that will be output if the associated attribute for the item has been changed or a '**.**' for no change. Otherwise a '**+**' is shown if the attribute has been added, a '**-**' if it has been removed, a '**:**' if the attribute is ignored (but not forced) or a ' ' if the attribute has not been checked. The exceptions to this are: (1) a newly created file replaces each letter with a '**+**', and (2) a removed file replaces each letter with a '**-**'. The attribute that is associated with each letter is as follows: - o An **l** means that the link name has changed. - o A **b** means that the block count has changed. - o A **p** means that the permissions have changed. - o A **u** means that the uid has changed. - o A **g** means that the gid has changed. - o An **a** means that the access time has changed. - o An **m** means that the modification time has changed. - o A **c** means that the change time has changed. - o An **i** means that the inode has changed. - o An **n** means that the link count has changed. - o An **H** means that one or more message digests have changed. - o An **F** means that one file system type has changed (Linux only). The following letters are only available when explicitly enabled using configure: - o An **A** means that the access control list has changed. - o An **X** means that the extended attributes have changed. - o An **S** means that the SELinux attributes have changed. - o An **E** means that the file attributes on a second extended file system have changed. - o A **C** means that the file capabilities have changed. - report\_ignore\_added\_attrs (type: attribute expression, default: **empty**, added in AIDE v0.16) Attributes whose addition is to be ignored in the report. - report\_ignore\_removed\_attrs (type: attribute expression, default: **empty**, added in AIDE v0.16) Attributes whose removal is to be ignored in the report. - report\_ignore\_changed\_attrs (type: attribute expression, default: **empty**, added in AIDE v0.16) ignore\_list (REMOVED in AIDE v0.17) Attributes whose change is to be ignored in the report. - report\_force\_attrs (type: attribute expression, default: **empty**, added in AIDE v0.16) report\_attributes (REMOVED in AIDE v0.17) Attributes which are always printed in the report for changed files. If an attribute is both ignored and forced the attribute is not considered for file change but printed in the final report as long as the file has been otherwise changed. - report\_ignore\_e2fsattrs (type: string, default: **0**, added in AIDE v0.16) List (no delimiter) of ext2 file attributes which are to be ignored in the report. See [**chattr**(1)](/chattr/1.md) for the available attributes. Use **0** (zero) to not ignore any attribute. Ignored attributes are represented by a ':' in the report. By default AIDE also reports changes of the read-only attributes mentioned in [**chattr**(1)](/chattr/1.md) (see example below how to ignore those changes). **Example:** Ignore changes of the read-only ext2 file attributes verify (V), inline data (N), indexed directory (I) and encrypted (E): ``` report_ignore_e2fsattrs=VNIE ``` ## GROUPS Groups are aggregations of attributes. Group definitions have the format \ = \. Group names are limited to alphanumeric characters (**A-Za-z0-9**). See ATTRIBUTES for a description of all available attributes. **Default groups** - **R** p+ftype+i+l+n+u+g+s+m+c+sha3\_256+X - **L** p+ftype+i+l+n+u+g+X - **\>** Growing file p+ftype+l+u+g+i+n+s+growing+X - **H** all compiled in (and not deprecated) hashsums (added in AIDE v0.17) - **X** acl+selinux+xattrs+e2fsattrs+caps (if attributes are compiled in, added in AIDE v0.16) - **E** Empty group - Use 'aide --version' to list the default compound groups. ## RULES AIDE supports three types of rules: - **Regular rule:** \ \ Files and directories matching the regular expression are added to the database. - **Recursive negative rule:** !\ Files and directories matching the regular expression are excluded and NOT added to the database. The children of directories and sub-directories are recursed into and only not added to the database if they also match the regular expression. - **Non-recursive negative rule (added in AIDE v0.19)** \-\ Files and directories matching the regular expression are excluded and NOT added the database. The children of directories and sub-directories are not recursed into and hence not added to the database by any means. - **Equals rule:** \=\ \ Files and directories matching the regular expression are added to the database. The children of directories are only added if the regular expression ends with a "/". The children of sub-directories are not added to the database. Every regular expression has to start with an explicit "/". An implicit ^ is added in front of each regular expression. In other words, the regular expressions are matched at the first position against the complete path. Special characters can be escaped using two-digit URL encoding (for example, %20 to represent a space). AIDE uses a deepest-match algorithm to find the tree node to search, but a first-match algorithm inside the node. (see also **rule** log level). See EXAMPLES for examples. More in-depth discussion of the selection algorithm can be found in the AIDE manual. - ## RESTRICTED RULES Restricted rules are like normal rules but can be restricted to file types (added in AIDE v0.16) and/or file system types (added in AIDE v0.19, Linux only). The syntax of restricted rules is as follows: **Restricted regular rule** ``` ``` Files and directories matching both the regular expression and the restriction expression are added the database. **Restricted recursive negative rule** ``` ! ``` Files and directories matching both the regular expression and the restriction expression are excluded and NOT added the database. The children of directories and sub-directories are recursed into and only excluded if they also match the regular expression as well as the restriction. **Restricted non-recursive negative rule (added in AIDE v0.19)** ``` - ``` Files and directories matching both the regular expression and the restriction expression are excluded and NOT added the database. The children of directories and sub-directories are not recursed into and hence not added to the database by any means. **Restricted equals rule** ``` = ``` Files and directories matching both the regular expression and the restriction expression are added the database. The children of directories are only added if the regular expression ends with a "/". The children of sub-directories are not added to the database. **Restriction expression** An restriction expression is of the following form: ``` : | = | = ``` **File types** The following file types are supported: - **f** restrict rule to regular files - **d** restrict rule to directories - **l** restrict rule to symbolic links - **c** restrict rule to character devices - **b** restrict rule to block devices - **p** restrict rule to FIFO files - **s** restrict rule to UNIX sockets - **D** restrict rule to Solaris doors - **P** restrict rule to Solaris event ports Multiple file type restrictions can be given as a comma-separated list. **File system types (Linux only)** The file system type restriction can be specified by file system types magic number (e.g. '0x01021994' for tmpfs) or by its name (use 'aide --version' to list the available file system type names). The magic number must start with '0x' and be formatted in hexdecimal format. **Empty restriction** To explicitly don't restrict a rule use **0** (added in AIDE v0.18). **Examples:** ``` / d,f R ``` Only add directories and files to the database. ``` /boot/efi$ d=vfat R ``` Only add **/boot/efi** to the database if it is a directory and mounted on **vfat**. ``` !/dev =0x01021994 ``` Exclude **/dev** and any children that are mounted on **tmpfs** (**tmpfs** magic number: **0x01021994**). ``` -/dev =tmpfs ``` Exclude **/dev** and all children, if **/dev** is mounted on **tmpfs**. ## MACRO LINES - @@define **VAR** **val** Define variable **VAR** to value **val**. - @@undef **VAR** Undefine variable **VAR**. - @@if **boolean\_expression** (added in AIDE v0.18) @@else @@endif @@if begins an if statement. It must be terminated with an @@endif statement. The lines between @@if and @@endif are used if the **boolean\_expression** evaluates to **true**. If there is an @@else statement then the part between @@if and @@else is used if **boolean\_expression** evaluates to **true** otherwise the part between @@else and @@endif is used. Available operators and functions in boolean expressions: ``` not boolean_expression ``` Evaluates to true if the *boolean\_expression* is false, and false if the *boolean\_expression* is true. ``` defined VARIABLE ``` Evaluates to **true** if *VARIABLE* is defined. ``` hostname HOSTNAME ``` Evaluates to **true** if *HOSTNAME* equals the **hostname** of the machine that AIDE is running on. **hostname** is the name of the host without the domainname (ie 'hostname', not 'hostname.example.com'). ``` exists PATH ``` Evaluates to **true** if *PATH* exists. ``` VERSION_STRING1 version_ge VERSION_STRING2 (added in AIDE v0.19) ``` Evaluates to **true** if *VERSION\_STRING1* is greater than or equal to *VERSION\_STRING2* (e.g. 0.19.1 **version\_ge** 0.18 evaluates to **true** and 2.17 **version\_ge** 1.1 to **false**). The version strings must be in the formaat MAJOR.MINOR.PATCH (minor and patch version can be omitted, any version suffix (e.g. for pre-release) will be truncated). - @@ifdef **VARIABLE** (**DEPRECATED** since AIDE v0.18, will be removed in AIDE v0.20) same as **@@if defined VARIABLE** - @@ifndef **VARIABLE** (**DEPRECATED** since AIDE v0.18, will be removed in AIDE v0.20) same as **@@if not defined VARIABLE** - @@ifhost **HOSTNAME** (**DEPRECATED** since AIDE v0.18, will be removed in AIDE v0.20) same as **@@if hostname HOSTNAME** - @@ifnhost **HOSTNAME** (**DEPRECATED** since AIDE v0.18, will be removed in AIDE v0.20) same as **@@if not hostname HOSTNAME** - @@{**VAR**} @@{**VAR**} is replaced with the value of the variable **VAR**. If variable **VAR** is not defined an empty string is used. Variables are supported in strings and in regular expressions of rules. Pre-defined marco variables: **@@{AIDE\_VERSION}**: the version of AIDE **@@{HOSTNAME}**: the hostname of the current system - @@include **FILE** Include **FILE**. The content of the file is used as if it were inserted in this part of the config file. The maximum depth of nested includes is 16. - @@include **DIRECTORY** **REGEX** \[**RULE\_PREFIX**\] (added in AIDE v0.17) Include all (regular) files found in **DIRECTORY** matching regular expression **REGEX** (sub-directories are ignored). The file are included in lexical sort order. If **RULE\_PREFIX** (added in AIDE v0.18) is set, all rules included by the statement are prefixed with given **RULE\_PREFIX**. Prefixes from nested include statements are concatenated. The content of the files is used as if it were inserted in this part of the config file. - @@x\_include **FILE** (added in AIDE v0.17) @@x\_include **DIRECTORY** **REGEX** \[**RULE\_PREFIX**\] (added in AIDE v0.17) **@x\_include** is identical to **@@include**, except that if a config file is executable is is run and the output is used as config. If the executable file exits with status greater than zero or writes to stderr aide stops with an error. For security reasons **DIRECTORY** and each executable config file must be owned by the current user or root. They must not be group- or world-writable. - @@x\_include\_setenv **VAR** **VALUE** (added in AIDE v0.17) Adds the variable **VAR** with the value **VALUE** to the environment used for config file execution. Environment variable names are limited to alphanumeric characters (**A-Za-z0-9**) and the underscore '**\_**' and must not begin with a digit. ## TYPES **bool** Valid values are **yes**, **true**, **no** or **false**. **attribute expression** An attribute expression is of the following form: - ``` : | + | - ``` **URLS** Urls can be one of the following. Input urls cannot be used as outputs and vice versa. - stdout - stderr Output is sent to stdout, stderr respectively. - stdin Input is read from stdin. - file:/**path** Input is read from **path** or output is written to **path**. - fd:**number** Input is read from filedescriptor **number** or output is written to **number**. - syslog:**LOG\_FACILITY** Output is written to syslog using *LOG\_FACILITY*. ## ATTRIBUTES **File attributes** - **ftype** file type (added in AIDE v0.15) - **fstype** file system type (Linux-only, added in AIDE v0.19) - **p** permissions - **i** inode - **l** link name (symbolic links only) - **n** number of links - **u** user - **g** group - **s** size - **b** block count - **m** mtime - **a** atime - **c** ctime - **acl** access control list (requires *libacl*, Linux-only) - **selinux** selinux attributes (requires *libselinux*, Linux-only) - **xattrs** extended attributes (requires *libattr*, Linux-only) - **e2fsattrs** file attributes on a Linux file system, see also **report\_ignore\_e2fsattrs** option (requires *libext2fs*, added in AIDE v0.15) - **caps** file capabilities (regular files only) (requires *libcap*, Linux-only, added in AIDE v0.17) Use 'aide --version' to show which compiled-in attributes are available. **Special attributes** - **S** check for growing size (**DEPRECATED** since AIDE v0.18, will be removed in AIDE v0.20) Use **growing+s** attributes instead - **I** ignore changed filename When **I** is used, the inode of the new file is used to search for a moved source file in the old database. Source and target file have to be located in the same directory and must share the same attributes (except for special attributes **ANF**, **ARF**, **I**, **growing**, and **compressed**). For moved entries a change of the **ctime** attribute is ignored. - **growing** ignore growing file (added in AIDE v0.18) When **growing** is used, changes of the following attributes are ignored: **size**: if new size is greater than old size **bcount**: if new bcount is greater than old bcount **atime**: if new atime is greater than old atime **mtime**: if new mtime is greater than old mtime **ctime**: if new ctime is greater than old ctime **hashsums**: if the hashsum of the new file restricted to the old size equals the hashsums of the old file For hashsum attributes the **growing** attribute is ignored in compare mode. - **compressed** ignore compressed file (added in AIDE v0.18) When **compressed** is used, the uncompressed hashsums of the new compressed file (supported compressions: **gzip**) are used to search for the uncompressed file in the old database. The old uncompressed and the new compressed file have to be located in the same directory and must share the same attributes (except for special attributes **ANF**, **ARF**, **I**, **growing**, and **compressed**) including at least one common hashsum. Changes of the **inode**, **size**, **bcount** and **ctime** attributes are ignored. The **growing** attribute (i.e. the old file size) is not considered for compressed files during the calculation of the uncompressed hashsums. The **compressed** attribute is ignored in compare mode. - **ANF** allow new files When 'ANF' is used, new files are added to the new database, but are ignored in the report. - **ARF** allow removed files When 'ARF' is used, files missing on disk are omitted from the new database, but are ignored in the report. **Hashsums attributes (regular files only)** - **sha256** SHA-256 checksum - **sha512** SHA-512 checksum - SHA-512 checksum truncated to 256 output bits - **sha512\_256** (added in AIDE v0.19) - SHA3-256 checksum - **sha3\_256** (added in AIDE v0.19) - SHA3-512 checksum - **sha3\_512** (added in AIDE v0.19) - GOST R 34.11-2012, 256 bit checksum - **stribog256** (added in AIDE v0.17) - GOST R 34.11-2012, 512 bit checksum - **stribog512** (added in AIDE v0.17) - MD5 checksum - md5 (**DEPRECATED** since AIDE v0.19, will be removed in AIDE v0.21) (not in *libgcrypt* FIPS mode) - SHA-1 checksum - sha1 (**DEPRECATED** since AIDE v0.19, will be removed in AIDE v0.21) - RIPEMD-160 checksum - rmd160 (**DEPRECATED** since AIDE v0.19, will be removed in AIDE v0.21) - GOST R 34.11-94 checksum - gost (**DEPRECATED** since AIDE v0.19, will be removed in AIDE v0.21) - crc32 checksum - crc32 (**REMOVED** in AIDE v0.19) - crc32 checksum - crc32b (**REMOVED** in AIDE v0.19) - haval256 checksum - haval (**REMOVED** in AIDE v0.19) - tiger checksum - tiger (**REMOVED** in AIDE v0.19) - whirlpool checksum - whirlpool (**REMOVED** in AIDE v0.19) Use 'aide --version' to show which hashsums are available. **Hashsum transitions (since AIDE v0.19):** AIDE has limited support for hashsum transitions (i.e. ensuring hashsum validation when hashsums are added/removed from existing entries). If both the old and the new entry do mot share common hashsum(s) AIDE tries to additionally calculate the removed hashsum(s) also for the new entry (this is especieally not supported for moved (**I** attribute) and compressed (**compressed** attribute) entries). ## EXAMPLES - **/ R** This adds all files on your machine to the database. This one line is a fully qualified configuration file. - **!/dev$** This ignores the /dev directory structure. - **=/foo R** Only /foo and /foobar are taken into the database. None of their children are added. - **=/foo/ R** Only /foo and its children (e.g. /foo/file and /foo/directory) are taken into the database. The children of sub-directories (e.g. /foo/directory/bar) are not added. - **/ d,f R** Only add directories and files to the database - **!/run d** **/run R** Add all but directory entries to the database - **/run d R-m-c-i** **/run R** Use specific rule for directories - Suggested Groups - **OwnerMode = p+u+g+ftype** Check permissions, owner, group and file type - **Size = s+b** Check size and block count - **InodeData = OwnerMode+n+i+Size+l+X** **StaticFile = m+c+Checksums** Files that stay static **Full = InodeData+StaticFile** - **Full = ftype+p+l+u+g+s+m+c+a+i+b+n+H+X** **/ 0 Full** This line defines group **Full**. It has all attributes, all compiled in hashsums (**H**) and all compiled in extra file attributes (**X**). See '--version' output for the compiled in hashsums and extra groups. The example rule is the typical catch-all rule at the end of the rule list. - **VarTime = InodeData+Checksums** **/etc/ssl/certs/ca-certificates\\\\.crt$ VarTime** Files that change their mtimes or ctimes but not their contents. - **VarInode = VarTime-i** **/var/lib/nfs/etab$ f VarInode** Files that are recreated regularly but do not change their contents - **VarFile = OwnerMode+n+l+X** **/etc/resolv\\\\.conf$ f VarFile** Files that change their contents during system operation - **VarDir = OwnerMode+n+i+X** **/var/lib/snmp$ d VarDir** Directories that change their contents during system operation - **RecreatedDir = OwnerMode+n+X** **/run/samba$ d RecreatedDir** Directories that are recreated regularly and change their contents - Log Handling Logs pose a number of special challenges to AIDE. An active log is nearly constantly being written to. The process of log rotation changes file names for files that are supposed to have unaltered contents. To save space, Logs are compressed in the process of their rotation, and finally, they get deleted. AIDE is supposed to handle all those cases without generating reports, and it is still expected to flag the cases when an attacker tampers with logs. The following examples suggest a way to handle the common case of log rotation with the [logrotate(8)](/logrotate/8.md) program, with its options **compress**, **delaycompress** and **nocopytruncate** set. The vast majority of logs are rotated this way on most Linux systems. - **ActLog=Full+growing+ANF+I** **/var/log/foo\\\\.log$ f ActLog** An Active Log is typically named foo.log. It is constanty being written to. The file does neither change its mode nor its inode number. The size only increases, and what is written to the file is not supposed to change (growing). During log rotation, foo.log is typically renamed to foo.log.1 (or foo.log.0) and the process is instructed to write to a new foo.log. Log content is written to a new file (ANF) and will eventually be renamed to foo.log.1 (I). The growing attribute suppresses reports for files that just had content appended when compared to the database. A change of the old content is still reported! - **RotLog=Full** **/var/log/foo\\\\.log\\\\.1$ f RotLog** foo.log.0 or foo.log.1 is called the Rotated Log, the previously active log renamed to the first name of the Log Series that is formed by the rotation mechanism. Right after rotation, the file might still being written to by the daemon. To aide, this looks like the Active Log's size decreases and its inode and timestamps change. The Rotated Log is not supposed to change its attributes once the process has stopped writing to it. Reports might be generated if aide runs while the process still writes to the Rotated Log, but this is quite unlikely to happen. Some log rotation mechanisms rename foo.log to foo.log.0 to foo.log.1.gz, others rename foo.log to foo.log.1 to foo.2.log.gz. - **CompSerLog=Full+I+compressed** **/var/log/foo\\\\.log\\\\.2\\\\.gz$ f CompSerLog** In the next rotation step, foo.log.1 gets compressed to foo.log.2.gz, becoming the Compressed Log in the Log Series. With this rule, AIDE does not report this step because it uncompresses the contents of the file and takes the checksum of the uncompressed content. The contents strictly doesn't change, but some attribute changes are ignored (compressed). - **MidlSerLog=Full+I** **/var/log/foo\\\\.log\\\\.\[345\]\\\\.gz$ f MidlSerLog** In the next log rotation, all foo.log.{x} get renamed to foo.log.{x+1}. The other attributes are not supposed to change. - **LastSerLog=Full+ARF** **/var/log/foo\\\\.log\\\\.6\\\\.gz$ f LastSerLog** The configuration of the log rotation process specifies a number of log generations to keep. The last log in the series is therefore removed from the disk (ARF). aide 0.18 does not yet support the following cases of log rotation: - **empty files** It might be the case that a log is actually created, but never written to. This commonly happens on rarely used web servers that use the log rotation as a method to cater for data protection regulation. In result, all files in a series are identical, breaking the heuristics that aide uses to detect log rotation. A possible workaround is to begin a newly rotated log with a timestamp. With logrotate, this can be done in a postrotate scriptlet. - **nodelaycompress** With logrotate's **nodelaycompress** option, a log is immediately compressed after renaming it from the Active Log name. For the time being, it is recommended to always use the **delaycompress** option to avoid this behavior. - **copytruncate** With logrotate's **copytruncate** option, the Active Log is not renamed and newly created but copied to the new file name. After the copy operation, the old file is truncated to zero size, allowing the daemon to continuously write to the already open file handle. aide uses the Inode number to detect the rotation process. That doesn't work with **copytruncate** because the Inode stays with the Active Log. For the time being, it is recommended to avoid the **copytruncate** option to avoid this behavior. ## HINTS In the following, the first is not allowed in AIDE. Use the latter instead. - **/foo epug** - **/foo e+p+u+g** ## SEE ALSO [**aide**(1)](/aide/1.md) ## DISCLAIMER All trademarks are the property of their respective owners. No animals were harmed while making this webpage or this piece of software.