diff --git a/auth-krb5.c b/auth-krb5.c
index a5a81ed2..63f877f2 100644
--- a/auth-krb5.c
+++ b/auth-krb5.c
@@ -51,6 +51,7 @@
#include <unistd.h>
#include <string.h>
#include <krb5.h>
+#include <profile.h>
extern ServerOptions options;
@@ -77,7 +78,7 @@ auth_krb5_password(Authctxt *authctxt, const char *password)
#endif
krb5_error_code problem;
krb5_ccache ccache = NULL;
- int len;
+ char *ticket_name = NULL;
char *client, *platform_client;
const char *errmsg;
@@ -163,7 +164,8 @@ auth_krb5_password(Authctxt *authctxt, const char *password)
goto out;
}
- problem = ssh_krb5_cc_gen(authctxt->krb5_ctx, &authctxt->krb5_fwd_ccache);
+ problem = ssh_krb5_cc_new_unique(authctxt->krb5_ctx,
+ &authctxt->krb5_fwd_ccache, &authctxt->krb5_set_env);
if (problem)
goto out;
@@ -172,21 +174,20 @@ auth_krb5_password(Authctxt *authctxt, const char *password)
if (problem)
goto out;
- problem= krb5_cc_store_cred(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache,
+ problem = krb5_cc_store_cred(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache,
&creds);
if (problem)
goto out;
#endif
- authctxt->krb5_ticket_file = (char *)krb5_cc_get_name(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
+ problem = krb5_cc_get_full_name(authctxt->krb5_ctx,
+ authctxt->krb5_fwd_ccache, &ticket_name);
- len = strlen(authctxt->krb5_ticket_file) + 6;
- authctxt->krb5_ccname = xmalloc(len);
- snprintf(authctxt->krb5_ccname, len, "FILE:%s",
- authctxt->krb5_ticket_file);
+ authctxt->krb5_ccname = xstrdup(ticket_name);
+ krb5_free_string(authctxt->krb5_ctx, ticket_name);
#ifdef USE_PAM
- if (options.use_pam)
+ if (options.use_pam && authctxt->krb5_set_env)
do_pam_putenv("KRB5CCNAME", authctxt->krb5_ccname);
#endif
@@ -222,11 +223,54 @@ auth_krb5_password(Authctxt *authctxt, const char *password)
void
krb5_cleanup_proc(Authctxt *authctxt)
{
+ struct stat krb5_ccname_stat;
+ char krb5_ccname[128], *krb5_ccname_dir_start, *krb5_ccname_dir_end;
+
debug("krb5_cleanup_proc called");
if (authctxt->krb5_fwd_ccache) {
- krb5_cc_destroy(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
+ krb5_context ctx = authctxt->krb5_ctx;
+ krb5_cccol_cursor cursor;
+ krb5_ccache ccache;
+ int ret;
+
+ krb5_cc_destroy(ctx, authctxt->krb5_fwd_ccache);
authctxt->krb5_fwd_ccache = NULL;
+
+ ret = krb5_cccol_cursor_new(ctx, &cursor);
+ if (ret)
+ goto out;
+
+ ret = krb5_cccol_cursor_next(ctx, cursor, &ccache);
+ if (ret == 0 && ccache != NULL) {
+ /* There is at least one other ccache in collection
+ * we can switch to */
+ krb5_cc_switch(ctx, ccache);
+ } else if (authctxt->krb5_ccname != NULL) {
+ /* Clean up the collection too */
+ strncpy(krb5_ccname, authctxt->krb5_ccname, sizeof(krb5_ccname) - 10);
+ krb5_ccname_dir_start = strchr(krb5_ccname, ':') + 1;
+ *krb5_ccname_dir_start++ = '\0';
+ if (strcmp(krb5_ccname, "DIR") == 0) {
+
+ strcat(krb5_ccname_dir_start, "/primary");
+
+ if (stat(krb5_ccname_dir_start, &krb5_ccname_stat) == 0) {
+ if (unlink(krb5_ccname_dir_start) == 0) {
+ krb5_ccname_dir_end = strrchr(krb5_ccname_dir_start, '/');
+ *krb5_ccname_dir_end = '\0';
+ if (rmdir(krb5_ccname_dir_start) == -1)
+ debug("cache dir '%s' remove failed: %s",
+ krb5_ccname_dir_start, strerror(errno));
+ }
+ else
+ debug("cache primary file '%s', remove failed: %s",
+ krb5_ccname_dir_start, strerror(errno));
+ }
+ }
+ }
+ krb5_cccol_cursor_free(ctx, &cursor);
}
+out:
if (authctxt->krb5_user) {
krb5_free_principal(authctxt->krb5_ctx, authctxt->krb5_user);
authctxt->krb5_user = NULL;
@@ -237,36 +281,188 @@ krb5_cleanup_proc(Authctxt *authctxt)
}
}
-#ifndef HEIMDAL
+
+#if !defined(HEIMDAL)
+int
+ssh_asprintf_append(char **dsc, const char *fmt, ...) {
+ char *src, *old;
+ va_list ap;
+ int i;
+
+ va_start(ap, fmt);
+ i = vasprintf(&src, fmt, ap);
+ va_end(ap);
+
+ if (i == -1 || src == NULL)
+ return -1;
+
+ old = *dsc;
+
+ i = asprintf(dsc, "%s%s", *dsc, src);
+ if (i == -1 || src == NULL) {
+ free(src);
+ return -1;
+ }
+
+ free(old);
+ free(src);
+
+ return i;
+}
+
+int
+ssh_krb5_expand_template(char **result, const char *template) {
+ char *p_n, *p_o, *r, *tmp_template;
+
+ debug3_f("called, template = %s", template);
+ if (template == NULL)
+ return -1;
+
+ tmp_template = p_n = p_o = xstrdup(template);
+ r = xstrdup("");
+
+ while ((p_n = strstr(p_o, "%{")) != NULL) {
+
+ *p_n++ = '\0';
+ if (ssh_asprintf_append(&r, "%s", p_o) == -1)
+ goto cleanup;
+
+ if (strncmp(p_n, "{uid}", 5) == 0 || strncmp(p_n, "{euid}", 6) == 0 ||
+ strncmp(p_n, "{USERID}", 8) == 0) {
+ p_o = strchr(p_n, '}') + 1;
+ if (ssh_asprintf_append(&r, "%d", geteuid()) == -1)
+ goto cleanup;
+ continue;
+ }
+ else if (strncmp(p_n, "{TEMP}", 6) == 0) {
+ p_o = strchr(p_n, '}') + 1;
+ if (ssh_asprintf_append(&r, "/tmp") == -1)
+ goto cleanup;
+ continue;
+ } else {
+ p_o = strchr(p_n, '}') + 1;
+ *p_o = '\0';
+ debug_f("unsupported token %s in %s", p_n, template);
+ /* unknown token, fallback to the default */
+ goto cleanup;
+ }
+ }
+
+ if (ssh_asprintf_append(&r, "%s", p_o) == -1)
+ goto cleanup;
+
+ *result = r;
+ free(tmp_template);
+ return 0;
+
+cleanup:
+ free(r);
+ free(tmp_template);
+ return -1;
+}
+
krb5_error_code
-ssh_krb5_cc_gen(krb5_context ctx, krb5_ccache *ccache) {
- int tmpfd, ret, oerrno;
- char ccname[40];
+ssh_krb5_get_cctemplate(krb5_context ctx, char **ccname) {
+ profile_t p;
+ int ret = 0;
+ char *value = NULL;
+
+ debug3_f("called");
+ ret = krb5_get_profile(ctx, &p);
+ if (ret)
+ return ret;
+
+ ret = profile_get_string(p, "libdefaults", "default_ccache_name", NULL, NULL, &value);
+ if (ret || !value)
+ return ret;
+
+ ret = ssh_krb5_expand_template(ccname, value);
+
+ debug3_f("returning with ccname = %s", *ccname);
+ return ret;
+}
+
+krb5_error_code
+ssh_krb5_cc_new_unique(krb5_context ctx, krb5_ccache *ccache, int *need_environment) {
+ int tmpfd, ret, oerrno, type_len;
+ char *ccname = NULL;
mode_t old_umask;
+ char *type = NULL, *colon = NULL;
- ret = snprintf(ccname, sizeof(ccname),
- "FILE:/tmp/krb5cc_%d_XXXXXXXXXX", geteuid());
- if (ret < 0 || (size_t)ret >= sizeof(ccname))
- return ENOMEM;
-
- old_umask = umask(0177);
- tmpfd = mkstemp(ccname + strlen("FILE:"));
- oerrno = errno;
- umask(old_umask);
- if (tmpfd == -1) {
- logit("mkstemp(): %.100s", strerror(oerrno));
- return oerrno;
- }
+ debug3_f("called");
+ if (need_environment)
+ *need_environment = 0;
+ ret = ssh_krb5_get_cctemplate(ctx, &ccname);
+ if (ret || !ccname || options.kerberos_unique_ccache) {
+ /* Otherwise, go with the old method */
+ if (ccname)
+ free(ccname);
+ ccname = NULL;
+
+ ret = asprintf(&ccname,
+ "FILE:/tmp/krb5cc_%d_XXXXXXXXXX", geteuid());
+ if (ret < 0)
+ return ENOMEM;
- if (fchmod(tmpfd,S_IRUSR | S_IWUSR) == -1) {
+ old_umask = umask(0177);
+ tmpfd = mkstemp(ccname + strlen("FILE:"));
oerrno = errno;
- logit("fchmod(): %.100s", strerror(oerrno));
+ umask(old_umask);
+ if (tmpfd == -1) {
+ logit("mkstemp(): %.100s", strerror(oerrno));
+ return oerrno;
+ }
+
+ if (fchmod(tmpfd,S_IRUSR | S_IWUSR) == -1) {
+ oerrno = errno;
+ logit("fchmod(): %.100s", strerror(oerrno));
+ close(tmpfd);
+ return oerrno;
+ }
+ /* make sure the KRB5CCNAME is set for non-standard location */
+ if (need_environment)
+ *need_environment = 1;
close(tmpfd);
- return oerrno;
}
- close(tmpfd);
- return (krb5_cc_resolve(ctx, ccname, ccache));
+ debug3_f("setting default ccname to %s", ccname);
+ /* set the default with already expanded user IDs */
+ ret = krb5_cc_set_default_name(ctx, ccname);
+ if (ret)
+ return ret;
+
+ if ((colon = strstr(ccname, ":")) != NULL) {
+ type_len = colon - ccname;
+ type = malloc((type_len + 1) * sizeof(char));
+ if (type == NULL)
+ return ENOMEM;
+ strncpy(type, ccname, type_len);
+ type[type_len] = 0;
+ } else {
+ type = strdup(ccname);
+ }
+
+ /* If we have a credential cache from krb5.conf, we need to switch
+ * a primary cache for this collection, if it supports that (non-FILE)
+ */
+ if (krb5_cc_support_switch(ctx, type)) {
+ debug3_f("calling cc_new_unique(%s)", ccname);
+ ret = krb5_cc_new_unique(ctx, type, NULL, ccache);
+ free(type);
+ if (ret)
+ return ret;
+
+ debug3_f("calling cc_switch()");
+ return krb5_cc_switch(ctx, *ccache);
+ } else {
+ /* Otherwise, we can not create a unique ccname here (either
+ * it is already unique from above or the type does not support
+ * collections
+ */
+ free(type);
+ debug3_f("calling cc_resolve(%s)", ccname);
+ return (krb5_cc_resolve(ctx, ccname, ccache));
+ }
}
#endif /* !HEIMDAL */
#endif /* KRB5 */
diff --git a/auth.h b/auth.h
index 29491df9..fdab5040 100644
--- a/auth.h
+++ b/auth.h
@@ -82,6 +82,7 @@ struct Authctxt {
krb5_principal krb5_user;
char *krb5_ticket_file;
char *krb5_ccname;
+ int krb5_set_env;
#endif
struct sshbuf *loginmsg;
@@ -238,7 +239,7 @@ int sys_auth_passwd(struct ssh *, const char *);
int sys_auth_passwd(struct ssh *, const char *);
#if defined(KRB5) && !defined(HEIMDAL)
-krb5_error_code ssh_krb5_cc_gen(krb5_context, krb5_ccache *);
+krb5_error_code ssh_krb5_cc_new_unique(krb5_context, krb5_ccache *, int *);
#endif
#endif /* AUTH_H */
diff -up openssh-7.9p1/gss-serv-krb5.c.ccache_name openssh-7.9p1/gss-serv-krb5.c
--- openssh-7.9p1/gss-serv-krb5.c.ccache_name 2019-03-01 15:17:42.708611802 +0100
+++ openssh-7.9p1/gss-serv-krb5.c 2019-03-01 15:17:42.713611844 +0100
@@ -267,7 +267,7 @@ ssh_gssapi_krb5_cmdok(krb5_principal pri
/* This writes out any forwarded credentials from the structure populated
* during userauth. Called after we have setuid to the user */
-static void
+static int
ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client)
{
krb5_ccache ccache;
@@ -276,14 +276,15 @@ ssh_gssapi_krb5_storecreds(ssh_gssapi_cl
OM_uint32 maj_status, min_status;
const char *new_ccname, *new_cctype;
const char *errmsg;
+ int set_env = 0;
if (client->creds == NULL) {
debug("No credentials stored");
- return;
+ return 0;
}
if (ssh_gssapi_krb5_init() == 0)
- return;
+ return 0;
#ifdef HEIMDAL
# ifdef HAVE_KRB5_CC_NEW_UNIQUE
@@ -297,14 +298,14 @@ ssh_gssapi_krb5_storecreds(ssh_gssapi_cl
krb5_get_err_text(krb_context, problem));
# endif
krb5_free_error_message(krb_context, errmsg);
- return;
+ return 0;
}
#else
- if ((problem = ssh_krb5_cc_gen(krb_context, &ccache))) {
+ if ((problem = ssh_krb5_cc_new_unique(krb_context, &ccache, &set_env)) != 0) {
errmsg = krb5_get_error_message(krb_context, problem);
- logit("ssh_krb5_cc_gen(): %.100s", errmsg);
+ logit("ssh_krb5_cc_new_unique(): %.100s", errmsg);
krb5_free_error_message(krb_context, errmsg);
- return;
+ return 0;
}
#endif /* #ifdef HEIMDAL */
@@ -313,7 +314,7 @@ ssh_gssapi_krb5_storecreds(ssh_gssapi_cl
errmsg = krb5_get_error_message(krb_context, problem);
logit("krb5_parse_name(): %.100s", errmsg);
krb5_free_error_message(krb_context, errmsg);
- return;
+ return 0;
}
if ((problem = krb5_cc_initialize(krb_context, ccache, princ))) {
@@ -322,7 +323,7 @@ ssh_gssapi_krb5_storecreds(ssh_gssapi_cl
krb5_free_error_message(krb_context, errmsg);
krb5_free_principal(krb_context, princ);
krb5_cc_destroy(krb_context, ccache);
- return;
+ return 0;
}
krb5_free_principal(krb_context, princ);
@@ -331,32 +332,21 @@ ssh_gssapi_krb5_storecreds(ssh_gssapi_cl
client->creds, ccache))) {
logit("gss_krb5_copy_ccache() failed");
krb5_cc_destroy(krb_context, ccache);
- return;
+ return 0;
}
new_cctype = krb5_cc_get_type(krb_context, ccache);
new_ccname = krb5_cc_get_name(krb_context, ccache);
-
- client->store.envvar = "KRB5CCNAME";
-#ifdef USE_CCAPI
- xasprintf(&client->store.envval, "API:%s", new_ccname);
- client->store.filename = NULL;
-#else
- if (new_ccname[0] == ':')
- new_ccname++;
xasprintf(&client->store.envval, "%s:%s", new_cctype, new_ccname);
- if (strcmp(new_cctype, "DIR") == 0) {
- char *p;
- p = strrchr(client->store.envval, '/');
- if (p)
- *p = '\0';
+
+ if (set_env) {
+ client->store.envvar = "KRB5CCNAME";
}
if ((strcmp(new_cctype, "FILE") == 0) || (strcmp(new_cctype, "DIR") == 0))
client->store.filename = xstrdup(new_ccname);
-#endif
#ifdef USE_PAM
- if (options.use_pam)
+ if (options.use_pam && set_env)
do_pam_putenv(client->store.envvar, client->store.envval);
#endif
@@ -361,7 +355,7 @@ ssh_gssapi_krb5_storecreds(ssh_gssapi_cl
client->store.data = krb_context;
- return;
+ return set_env;
}
int
diff --git a/gss-serv.c b/gss-serv.c
index 6cae720e..16e55cbc 100644
--- a/gss-serv.c
+++ b/gss-serv.c
@@ -320,13 +320,15 @@ ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client)
}
/* As user */
-void
+int
ssh_gssapi_storecreds(void)
{
if (gssapi_client.mech && gssapi_client.mech->storecreds) {
- (*gssapi_client.mech->storecreds)(&gssapi_client);
+ return (*gssapi_client.mech->storecreds)(&gssapi_client);
} else
debug("ssh_gssapi_storecreds: Not a GSSAPI mechanism");
+
+ return 0;
}
/* This allows GSSAPI methods to do things to the child's environment based
@@ -498,9 +500,7 @@ ssh_gssapi_rekey_creds() {
char *envstr;
#endif
- if (gssapi_client.store.filename == NULL &&
- gssapi_client.store.envval == NULL &&
- gssapi_client.store.envvar == NULL)
+ if (gssapi_client.store.envval == NULL)
return;
ok = PRIVSEP(ssh_gssapi_update_creds(&gssapi_client.store));
diff -up openssh-7.9p1/servconf.c.ccache_name openssh-7.9p1/servconf.c
--- openssh-7.9p1/servconf.c.ccache_name 2019-03-01 15:17:42.704611768 +0100
+++ openssh-7.9p1/servconf.c 2019-03-01 15:17:42.713611844 +0100
@@ -123,6 +123,7 @@ initialize_server_options(ServerOptions
options->kerberos_or_local_passwd = -1;
options->kerberos_ticket_cleanup = -1;
options->kerberos_get_afs_token = -1;
+ options->kerberos_unique_ccache = -1;
options->gss_authentication=-1;
options->gss_keyex = -1;
options->gss_cleanup_creds = -1;
@@ -315,6 +316,8 @@ fill_default_server_options(ServerOptions *options)
options->kerberos_ticket_cleanup = 1;
if (options->kerberos_get_afs_token == -1)
options->kerberos_get_afs_token = 0;
+ if (options->kerberos_unique_ccache == -1)
+ options->kerberos_unique_ccache = 0;
if (options->gss_authentication == -1)
options->gss_authentication = 0;
if (options->gss_keyex == -1)
@@ -447,7 +450,8 @@ typedef enum {
sPermitRootLogin, sLogFacility, sLogLevel, sLogVerbose,
sRhostsRSAAuthentication, sRSAAuthentication,
sKerberosAuthentication, sKerberosOrLocalPasswd, sKerberosTicketCleanup,
- sKerberosGetAFSToken, sChallengeResponseAuthentication,
+ sKerberosGetAFSToken, sKerberosUniqueCCache,
+ sChallengeResponseAuthentication,
sPasswordAuthentication, sKbdInteractiveAuthentication,
sListenAddress, sAddressFamily,
sPrintMotd, sPrintLastLog, sIgnoreRhosts,
@@ -526,11 +530,13 @@ static struct {
#else
{ "kerberosgetafstoken", sUnsupported, SSHCFG_GLOBAL },
#endif
+ { "kerberosuniqueccache", sKerberosUniqueCCache, SSHCFG_GLOBAL },
#else
{ "kerberosauthentication", sUnsupported, SSHCFG_ALL },
{ "kerberosorlocalpasswd", sUnsupported, SSHCFG_GLOBAL },
{ "kerberosticketcleanup", sUnsupported, SSHCFG_GLOBAL },
{ "kerberosgetafstoken", sUnsupported, SSHCFG_GLOBAL },
+ { "kerberosuniqueccache", sUnsupported, SSHCFG_GLOBAL },
#endif
{ "kerberostgtpassing", sUnsupported, SSHCFG_GLOBAL },
{ "afstokenpassing", sUnsupported, SSHCFG_GLOBAL },
@@ -1437,6 +1443,10 @@ process_server_config_line(ServerOptions *options, char *line,
intptr = &options->kerberos_get_afs_token;
goto parse_flag;
+ case sKerberosUniqueCCache:
+ intptr = &options->kerberos_unique_ccache;
+ goto parse_flag;
+
case sGssAuthentication:
intptr = &options->gss_authentication;
goto parse_flag;
@@ -2507,6 +2517,7 @@ dump_config(ServerOptions *o)
# ifdef USE_AFS
dump_cfg_fmtint(sKerberosGetAFSToken, o->kerberos_get_afs_token);
# endif
+ dump_cfg_fmtint(sKerberosUniqueCCache, o->kerberos_unique_ccache);
#endif
#ifdef GSSAPI
dump_cfg_fmtint(sGssAuthentication, o->gss_authentication);
diff --git a/servconf.h b/servconf.h
index db8362c6..4fa42d64 100644
--- a/servconf.h
+++ b/servconf.h
@@ -123,6 +123,8 @@ typedef struct {
* file on logout. */
int kerberos_get_afs_token; /* If true, try to get AFS token if
* authenticated with Kerberos. */
+ int kerberos_unique_ccache; /* If true, the acquired ticket will
+ * be stored in per-session ccache */
int gss_authentication; /* If true, permit GSSAPI authentication */
int gss_keyex; /* If true, permit GSSAPI key exchange */
int gss_cleanup_creds; /* If true, destroy cred cache on logout */
diff --git a/session.c b/session.c
index 85df6a27..480a5ead 100644
--- a/session.c
+++ b/session.c
@@ -1033,7 +1033,8 @@ do_setup_env(struct ssh *ssh, Session *s, const char *shell)
/* Allow any GSSAPI methods that we've used to alter
* the child's environment as they see fit
*/
- ssh_gssapi_do_child(&env, &envsize);
+ if (s->authctxt->krb5_set_env)
+ ssh_gssapi_do_child(&env, &envsize);
#endif
/* Set basic environment. */
@@ -1105,7 +1106,7 @@ do_setup_env(struct ssh *ssh, Session *s, const char *shell)
}
#endif
#ifdef KRB5
- if (s->authctxt->krb5_ccname)
+ if (s->authctxt->krb5_ccname && s->authctxt->krb5_set_env)
child_set_env(&env, &envsize, "KRB5CCNAME",
s->authctxt->krb5_ccname);
#endif
diff --git a/ssh-gss.h b/ssh-gss.h
index 6593e422..245178af 100644
--- a/ssh-gss.h
+++ b/ssh-gss.h
@@ -83,7 +82,7 @@ typedef struct ssh_gssapi_mech_struct {
int (*dochild) (ssh_gssapi_client *);
int (*userok) (ssh_gssapi_client *, char *);
int (*localname) (ssh_gssapi_client *, char **);
- void (*storecreds) (ssh_gssapi_client *);
+ int (*storecreds) (ssh_gssapi_client *);
int (*updatecreds) (ssh_gssapi_ccache *, ssh_gssapi_client *);
} ssh_gssapi_mech;
@@ -127,7 +126,7 @@ int ssh_gssapi_userok(char *name);
OM_uint32 ssh_gssapi_checkmic(Gssctxt *, gss_buffer_t, gss_buffer_t);
void ssh_gssapi_do_child(char ***, u_int *);
void ssh_gssapi_cleanup_creds(void);
-void ssh_gssapi_storecreds(void);
+int ssh_gssapi_storecreds(void);
const char *ssh_gssapi_displayname(void);
char *ssh_gssapi_server_mechanisms(void);
diff --git a/sshd.c b/sshd.c
index edbe815c..89514e8a 100644
--- a/sshd.c
+++ b/sshd.c
@@ -2162,7 +2162,7 @@ main(int ac, char **av)
#ifdef GSSAPI
if (options.gss_authentication) {
temporarily_use_uid(authctxt->pw);
- ssh_gssapi_storecreds();
+ authctxt->krb5_set_env = ssh_gssapi_storecreds();
restore_uid();
}
#endif
diff --git a/sshd_config.5 b/sshd_config.5
index c0683d4a..2349f477 100644
--- a/sshd_config.5
+++ b/sshd_config.5
@@ -860,6 +860,14 @@ Specifies whether to automatically destroy the user's ticket cache
file on logout.
The default is
.Cm yes .
+.It Cm KerberosUniqueCCache
+Specifies whether to store the acquired tickets in the per-session credential
+cache under /tmp/ or whether to use per-user credential cache as configured in
+.Pa /etc/krb5.conf .
+The default value
+.Cm no
+can lead to overwriting previous tickets by subseqent connections to the same
+user account.
.It Cm KexAlgorithms
Specifies the available KEX (Key Exchange) algorithms.
Multiple algorithms must be comma-separated.