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From 9ec4db016a0510c449f9cefeb3299c2e755698c7 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: 2018-04-03
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 3fff3d531..0a8f6fd62 100644
--- a/servconf.c
+++ b/servconf.c
@@ -177,6 +177,7 @@ initialize_server_options(ServerOptions *options)
options->fingerprint_hash = -1;
options->disable_forwarding = -1;
options->expose_userauth_info = -1;
+ options->debian_banner = -1;
}
/* Returns 1 if a string option is unset or set to "none" or 0 otherwise. */
@@ -393,6 +394,8 @@ fill_default_server_options(ServerOptions *options)
options->disable_forwarding = 0;
if (options->expose_userauth_info == -1)
options->expose_userauth_info = 0;
+ if (options->debian_banner == -1)
+ options->debian_banner = 1;
assemble_algorithms(options);
@@ -480,6 +483,7 @@ typedef enum {
sStreamLocalBindMask, sStreamLocalBindUnlink,
sAllowStreamLocalForwarding, sFingerprintHash, sDisableForwarding,
sExposeAuthInfo, sRDomain,
+ sDebianBanner,
sDeprecated, sIgnore, sUnsupported
} ServerOpCodes;
@@ -634,6 +638,7 @@ static struct {
{ "disableforwarding", sDisableForwarding, SSHCFG_ALL },
{ "exposeauthinfo", sExposeAuthInfo, SSHCFG_ALL },
{ "rdomain", sRDomain, SSHCFG_ALL },
+ { "debianbanner", sDebianBanner, SSHCFG_GLOBAL },
{ NULL, sBadOption, 0 }
};
@@ -2056,6 +2061,10 @@ process_server_config_line(ServerOptions *options, char *line,
*charptr = xstrdup(arg);
break;
+ case sDebianBanner:
+ intptr = &options->debian_banner;
+ goto parse_flag;
+
case sDeprecated:
case sIgnore:
case sUnsupported:
diff --git a/servconf.h b/servconf.h
index 5dfc9bc02..b0fa70455 100644
--- a/servconf.h
+++ b/servconf.h
@@ -211,6 +211,8 @@ typedef struct {
int fingerprint_hash;
int expose_userauth_info;
+
+ int debian_banner;
} ServerOptions;
/* Information about the incoming connection as used by Match */
diff --git a/sshd.c b/sshd.c
index 9a7f5495c..1d645a170 100644
--- a/sshd.c
+++ b/sshd.c
@@ -384,7 +384,8 @@ sshd_exchange_identification(struct ssh *ssh, int sock_in, int sock_out)
char remote_version[256]; /* Must be at least as big as buf. */
xasprintf(&server_version_string, "SSH-%d.%d-%.100s%s%s\r\n",
- PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_RELEASE,
+ PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2,
+ options.debian_banner ? SSH_RELEASE : SSH_RELEASE_MINIMUM,
*options.version_addendum == '\0' ? "" : " ",
options.version_addendum);
diff --git a/sshd_config.5 b/sshd_config.5
index 1a1c6dd09..45044a70f 100644
--- a/sshd_config.5
+++ b/sshd_config.5
@@ -531,6 +531,11 @@ or
.Cm no .
The default is
.Cm yes .
+.It Cm DebianBanner
+Specifies whether the distribution-specified extra version suffix is
+included during initial protocol handshake.
+The default is
+.Cm yes .
.It Cm DenyGroups
This keyword can be followed by a list of group name patterns, separated
by spaces.
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