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From 781bef6cb1a423864072a07c08c9ae95c554b07a Mon Sep 17 00:00:00 2001
From: Kees Cook <kees@debian.org>
Date: Sun, 9 Feb 2014 16:10:06 +0000
Subject: Add DebianBanner server configuration option
Setting this to "no" causes sshd to omit the Debian revision from its
initial protocol handshake, for those scared by package-versioning.patch.
Bug-Debian: http://bugs.debian.org/562048
Forwarded: not-needed
Last-Update: 2015-08-19
Patch-Name: debian-banner.patch
---
servconf.c | 9 +++++++++
servconf.h | 2 ++
sshd.c | 3 ++-
sshd_config.5 | 5 +++++
4 files changed, 18 insertions(+), 1 deletion(-)
diff --git a/servconf.c b/servconf.c
index 8a5bd7b..fe3e311 100644
--- a/servconf.c
+++ b/servconf.c
@@ -169,6 +169,7 @@ initialize_server_options(ServerOptions *options)
options->ip_qos_bulk = -1;
options->version_addendum = NULL;
options->fingerprint_hash = -1;
+ options->debian_banner = -1;
}
/* Returns 1 if a string option is unset or set to "none" or 0 otherwise. */
@@ -347,6 +348,8 @@ fill_default_server_options(ServerOptions *options)
options->fwd_opts.streamlocal_bind_unlink = 0;
if (options->fingerprint_hash == -1)
options->fingerprint_hash = SSH_FP_HASH_DEFAULT;
+ if (options->debian_banner == -1)
+ options->debian_banner = 1;
/* Turn privilege separation on by default */
if (use_privsep == -1)
use_privsep = PRIVSEP_NOSANDBOX;
@@ -419,6 +422,7 @@ typedef enum {
sAuthenticationMethods, sHostKeyAgent, sPermitUserRC,
sStreamLocalBindMask, sStreamLocalBindUnlink,
sAllowStreamLocalForwarding, sFingerprintHash,
+ sDebianBanner,
sDeprecated, sUnsupported
} ServerOpCodes;
@@ -565,6 +569,7 @@ static struct {
{ "streamlocalbindunlink", sStreamLocalBindUnlink, SSHCFG_ALL },
{ "allowstreamlocalforwarding", sAllowStreamLocalForwarding, SSHCFG_ALL },
{ "fingerprinthash", sFingerprintHash, SSHCFG_GLOBAL },
+ { "debianbanner", sDebianBanner, SSHCFG_GLOBAL },
{ NULL, sBadOption, 0 }
};
@@ -1850,6 +1855,10 @@ process_server_config_line(ServerOptions *options, char *line,
options->fingerprint_hash = value;
break;
+ case sDebianBanner:
+ intptr = &options->debian_banner;
+ goto parse_int;
+
case sDeprecated:
logit("%s line %d: Deprecated option %s",
filename, linenum, arg);
diff --git a/servconf.h b/servconf.h
index b99b270..ba7b739 100644
--- a/servconf.h
+++ b/servconf.h
@@ -196,6 +196,8 @@ typedef struct {
char *auth_methods[MAX_AUTH_METHODS];
int fingerprint_hash;
+
+ int debian_banner;
} ServerOptions;
/* Information about the incoming connection as used by Match */
diff --git a/sshd.c b/sshd.c
index 96e75c6..7886d0e 100644
--- a/sshd.c
+++ b/sshd.c
@@ -442,7 +442,8 @@ sshd_exchange_identification(int sock_in, int sock_out)
}
xasprintf(&server_version_string, "SSH-%d.%d-%.100s%s%s%s",
- major, minor, SSH_RELEASE,
+ major, minor,
+ options.debian_banner ? SSH_RELEASE : SSH_RELEASE_MINIMUM,
*options.version_addendum == '\0' ? "" : " ",
options.version_addendum, newline);
diff --git a/sshd_config.5 b/sshd_config.5
index 1269bbd..a5afbc3 100644
--- a/sshd_config.5
+++ b/sshd_config.5
@@ -528,6 +528,11 @@ or
.Dq no .
The default is
.Dq delayed .
+.It Cm DebianBanner
+Specifies whether the distribution-specified extra version suffix is
+included during initial protocol handshake.
+The default is
+.Dq yes .
.It Cm DenyGroups
This keyword can be followed by a list of group name patterns, separated
by spaces.
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